This commit adds a new rcutorture.n_up_down kernel boot parameter
that specifies the number of outstanding SRCU up/down readers, which
begin in kthread context and end in an hrtimer handler. There is a new
kthread ("rcu_torture_updown") that scans an per-reader array looking
for elements whose readers have ended. This kthread sleeps between one
and two milliseconds between consecutive scans.
[ paulmck: Apply kernel test robot feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/rcutorture.c | 227 ++++++++++++++++++++++++++++++++++++----
1 file changed, 208 insertions(+), 19 deletions(-)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index b0e96df636226..6afcd33e724ba 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -55,22 +55,24 @@ MODULE_DESCRIPTION("Read-Copy Update module-based torture test facility");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
-/* Bits for ->extendables field, extendables param, and related definitions. */
-#define RCUTORTURE_RDR_SHIFT_1 8 /* Put SRCU index in upper bits. */
-#define RCUTORTURE_RDR_MASK_1 (0xff << RCUTORTURE_RDR_SHIFT_1)
-#define RCUTORTURE_RDR_SHIFT_2 16 /* Put SRCU index in upper bits. */
-#define RCUTORTURE_RDR_MASK_2 (0xff << RCUTORTURE_RDR_SHIFT_2)
-#define RCUTORTURE_RDR_BH 0x01 /* Extend readers by disabling bh. */
-#define RCUTORTURE_RDR_IRQ 0x02 /* ... disabling interrupts. */
-#define RCUTORTURE_RDR_PREEMPT 0x04 /* ... disabling preemption. */
-#define RCUTORTURE_RDR_RBH 0x08 /* ... rcu_read_lock_bh(). */
-#define RCUTORTURE_RDR_SCHED 0x10 /* ... rcu_read_lock_sched(). */
-#define RCUTORTURE_RDR_RCU_1 0x20 /* ... entering another RCU reader. */
-#define RCUTORTURE_RDR_RCU_2 0x40 /* ... entering another RCU reader. */
-#define RCUTORTURE_RDR_NBITS 7 /* Number of bits defined above. */
-#define RCUTORTURE_MAX_EXTEND \
+// Bits for ->extendables field, extendables param, and related definitions.
+#define RCUTORTURE_RDR_SHIFT_1 8 // Put SRCU index in upper bits.
+#define RCUTORTURE_RDR_MASK_1 (0xff << RCUTORTURE_RDR_SHIFT_1)
+#define RCUTORTURE_RDR_SHIFT_2 16 // Put SRCU index in upper bits.
+#define RCUTORTURE_RDR_MASK_2 (0xff << RCUTORTURE_RDR_SHIFT_2)
+#define RCUTORTURE_RDR_BH 0x01 // Extend readers by disabling bh.
+#define RCUTORTURE_RDR_IRQ 0x02 // ... disabling interrupts.
+#define RCUTORTURE_RDR_PREEMPT 0x04 // ... disabling preemption.
+#define RCUTORTURE_RDR_RBH 0x08 // ... rcu_read_lock_bh().
+#define RCUTORTURE_RDR_SCHED 0x10 // ... rcu_read_lock_sched().
+#define RCUTORTURE_RDR_RCU_1 0x20 // ... entering another RCU reader.
+#define RCUTORTURE_RDR_RCU_2 0x40 // ... entering another RCU reader.
+#define RCUTORTURE_RDR_UPDOWN 0x80 // ... up-read from task, down-read from timer.
+ // Note: Manual start, automatic end.
+#define RCUTORTURE_RDR_NBITS 8 // Number of bits defined above.
+#define RCUTORTURE_MAX_EXTEND \
(RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
- RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
+ RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED) // Intentionally omit RCUTORTURE_RDR_UPDOWN.
#define RCUTORTURE_RDR_ALLBITS \
(RCUTORTURE_MAX_EXTEND | RCUTORTURE_RDR_RCU_1 | RCUTORTURE_RDR_RCU_2 | \
RCUTORTURE_RDR_MASK_1 | RCUTORTURE_RDR_MASK_2)
@@ -110,6 +112,7 @@ torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
torture_param(int, leakpointer, 0, "Leak pointer dereferences from readers");
torture_param(int, n_barrier_cbs, 0, "# of callbacks/kthreads for barrier testing");
+torture_param(int, n_up_down, 32, "# of concurrent up/down hrtimer-based RCU readers");
torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
torture_param(int, nreaders, -1, "Number of RCU reader threads");
torture_param(int, object_debug, 0, "Enable debug-object double call_rcu() testing");
@@ -152,6 +155,7 @@ static int nrealfakewriters;
static struct task_struct *writer_task;
static struct task_struct **fakewriter_tasks;
static struct task_struct **reader_tasks;
+static struct task_struct *updown_task;
static struct task_struct **nocb_tasks;
static struct task_struct *stats_task;
static struct task_struct *fqs_task;
@@ -374,6 +378,8 @@ struct rcu_torture_ops {
void (*readunlock)(int idx);
int (*readlock_held)(void); // lockdep.
int (*readlock_nesting)(void); // actual nesting, if available, -1 if not.
+ int (*down_read)(void);
+ void (*up_read)(int idx);
unsigned long (*get_gp_seq)(void);
unsigned long (*gp_diff)(unsigned long new, unsigned long old);
void (*deferred_free)(struct rcu_torture *p);
@@ -421,6 +427,7 @@ struct rcu_torture_ops {
int no_pi_lock;
int debug_objects;
int start_poll_irqsoff;
+ int have_up_down;
const char *name;
};
@@ -754,6 +761,50 @@ static int torture_srcu_read_lock_held(void)
return srcu_read_lock_held(srcu_ctlp);
}
+static bool srcu_torture_have_up_down(void)
+{
+ int rf = reader_flavor;
+
+ if (!rf)
+ rf = SRCU_READ_FLAVOR_NORMAL;
+ return !!(cur_ops->have_up_down & rf);
+}
+
+static int srcu_torture_down_read(void)
+{
+ int idx;
+ struct srcu_ctr __percpu *scp;
+
+ WARN_ON_ONCE(reader_flavor & ~SRCU_READ_FLAVOR_ALL);
+ WARN_ON_ONCE(reader_flavor & (reader_flavor - 1));
+
+ if ((reader_flavor & SRCU_READ_FLAVOR_NORMAL) || !(reader_flavor & SRCU_READ_FLAVOR_ALL)) {
+ idx = srcu_down_read(srcu_ctlp);
+ WARN_ON_ONCE(idx & ~0x1);
+ return idx;
+ }
+ if (reader_flavor & SRCU_READ_FLAVOR_FAST) {
+ scp = srcu_down_read_fast(srcu_ctlp);
+ idx = __srcu_ptr_to_ctr(srcu_ctlp, scp);
+ WARN_ON_ONCE(idx & ~0x1);
+ return idx << 3;
+ }
+ WARN_ON_ONCE(1);
+ return 0;
+}
+
+static void srcu_torture_up_read(int idx)
+{
+ WARN_ON_ONCE((reader_flavor && (idx & ~reader_flavor)) || (!reader_flavor && (idx & ~0x1)));
+ if (reader_flavor & SRCU_READ_FLAVOR_FAST)
+ srcu_up_read_fast(srcu_ctlp, __srcu_ctr_to_ptr(srcu_ctlp, (idx & 0x8) >> 3));
+ else if ((reader_flavor & SRCU_READ_FLAVOR_NORMAL) ||
+ !(reader_flavor & SRCU_READ_FLAVOR_ALL))
+ srcu_up_read(srcu_ctlp, idx & 0x1);
+ else
+ WARN_ON_ONCE(1);
+}
+
static unsigned long srcu_torture_completed(void)
{
return srcu_batches_completed(srcu_ctlp);
@@ -811,6 +862,8 @@ static struct rcu_torture_ops srcu_ops = {
.readlock = srcu_torture_read_lock,
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock,
+ .down_read = srcu_torture_down_read,
+ .up_read = srcu_torture_up_read,
.readlock_held = torture_srcu_read_lock_held,
.get_gp_seq = srcu_torture_completed,
.gp_diff = rcu_seq_diff,
@@ -831,6 +884,8 @@ static struct rcu_torture_ops srcu_ops = {
.irq_capable = 1,
.no_pi_lock = IS_ENABLED(CONFIG_TINY_SRCU),
.debug_objects = 1,
+ .have_up_down = IS_ENABLED(CONFIG_TINY_SRCU)
+ ? 0 : SRCU_READ_FLAVOR_NORMAL | SRCU_READ_FLAVOR_FAST,
.name = "srcu"
};
@@ -856,6 +911,8 @@ static struct rcu_torture_ops srcud_ops = {
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock,
.readlock_held = torture_srcu_read_lock_held,
+ .down_read = srcu_torture_down_read,
+ .up_read = srcu_torture_up_read,
.get_gp_seq = srcu_torture_completed,
.gp_diff = rcu_seq_diff,
.deferred_free = srcu_torture_deferred_free,
@@ -875,6 +932,8 @@ static struct rcu_torture_ops srcud_ops = {
.irq_capable = 1,
.no_pi_lock = IS_ENABLED(CONFIG_TINY_SRCU),
.debug_objects = 1,
+ .have_up_down = IS_ENABLED(CONFIG_TINY_SRCU)
+ ? 0 : SRCU_READ_FLAVOR_NORMAL | SRCU_READ_FLAVOR_FAST,
.name = "srcud"
};
@@ -1985,7 +2044,7 @@ static void rcutorture_one_extend(int *readstate, int newstate, bool insoftirq,
first = idxold1 == 0;
WARN_ON_ONCE(idxold2 < 0);
- WARN_ON_ONCE(idxold2 & ~RCUTORTURE_RDR_ALLBITS);
+ WARN_ON_ONCE(idxold2 & ~(RCUTORTURE_RDR_ALLBITS | RCUTORTURE_RDR_UPDOWN));
rcutorture_one_extend_check("before change", idxold1, statesnew, statesold, insoftirq);
rtrsp->rt_readstate = newstate;
@@ -2061,6 +2120,11 @@ static void rcutorture_one_extend(int *readstate, int newstate, bool insoftirq,
if (lockit)
raw_spin_unlock_irqrestore(¤t->pi_lock, flags);
}
+ if (statesold & RCUTORTURE_RDR_UPDOWN) {
+ cur_ops->up_read((idxold1 & RCUTORTURE_RDR_MASK_1) >> RCUTORTURE_RDR_SHIFT_1);
+ WARN_ON_ONCE(idxnew1 != -1);
+ idxold1 = 0;
+ }
/* Delay if neither beginning nor end and there was a change. */
if ((statesnew || statesold) && *readstate && newstate)
@@ -2201,7 +2265,8 @@ static bool rcu_torture_one_read_start(struct rcu_torture_one_read_state *rtorsp
rtorsp->started = cur_ops->get_gp_seq();
rtorsp->ts = rcu_trace_clock_local();
rtorsp->p = rcu_dereference_check(rcu_torture_current,
- !cur_ops->readlock_held || cur_ops->readlock_held());
+ !cur_ops->readlock_held || cur_ops->readlock_held() ||
+ (rtorsp->readstate & RCUTORTURE_RDR_UPDOWN));
if (rtorsp->p == NULL) {
/* Wait for rcu_torture_writer to get underway */
rcutorture_one_extend(&rtorsp->readstate, 0, myid < 0, trsp, rtorsp->rtrsp);
@@ -2370,6 +2435,123 @@ rcu_torture_reader(void *arg)
return 0;
}
+struct rcu_torture_one_read_state_updown {
+ struct hrtimer rtorsu_hrt;
+ bool rtorsu_inuse;
+ struct torture_random_state rtorsu_trs;
+ struct rcu_torture_one_read_state rtorsu_rtors;
+};
+
+static struct rcu_torture_one_read_state_updown *updownreaders;
+static DEFINE_TORTURE_RANDOM(rcu_torture_updown_rand);
+static int rcu_torture_updown(void *arg);
+
+static enum hrtimer_restart rcu_torture_updown_hrt(struct hrtimer *hrtp)
+{
+ struct rcu_torture_one_read_state_updown *rtorsup;
+
+ rtorsup = container_of(hrtp, struct rcu_torture_one_read_state_updown, rtorsu_hrt);
+ rcu_torture_one_read_end(&rtorsup->rtorsu_rtors, &rtorsup->rtorsu_trs, -1);
+ smp_store_release(&rtorsup->rtorsu_inuse, false);
+ return HRTIMER_NORESTART;
+}
+
+static int rcu_torture_updown_init(void)
+{
+ int i;
+ struct torture_random_state *rand = &rcu_torture_updown_rand;
+ int ret;
+
+ if (n_up_down < 0)
+ return 0;
+ if (!srcu_torture_have_up_down()) {
+ VERBOSE_TOROUT_STRING("rcu_torture_updown_init: Disabling up/down reader tests due to lack of primitives");
+ return 0;
+ }
+ updownreaders = kcalloc(n_up_down, sizeof(*updownreaders), GFP_KERNEL);
+ if (!updownreaders) {
+ VERBOSE_TOROUT_STRING("rcu_torture_updown_init: Out of memory, disabling up/down reader tests");
+ return -ENOMEM;
+ }
+ for (i = 0; i < n_up_down; i++) {
+ init_rcu_torture_one_read_state(&updownreaders[i].rtorsu_rtors, rand);
+ hrtimer_init(&updownreaders[i].rtorsu_hrt, CLOCK_MONOTONIC,
+ HRTIMER_MODE_REL | HRTIMER_MODE_SOFT);
+ updownreaders[i].rtorsu_hrt.function = rcu_torture_updown_hrt;
+ torture_random_init(&updownreaders[i].rtorsu_trs);
+ init_rcu_torture_one_read_state(&updownreaders[i].rtorsu_rtors,
+ &updownreaders[i].rtorsu_trs);
+ }
+ ret = torture_create_kthread(rcu_torture_updown, rand, updown_task);
+ if (ret) {
+ kfree(updownreaders);
+ updownreaders = NULL;
+ }
+ return ret;
+}
+
+static void rcu_torture_updown_cleanup(void)
+{
+ struct rcu_torture_one_read_state_updown *rtorsup;
+
+ for (rtorsup = updownreaders; rtorsup < &updownreaders[n_up_down]; rtorsup++) {
+ if (!smp_load_acquire(&rtorsup->rtorsu_inuse))
+ continue;
+ (void)hrtimer_cancel(&rtorsup->rtorsu_hrt);
+ WARN_ON_ONCE(rtorsup->rtorsu_inuse);
+
+ }
+ kfree(updownreaders);
+ updownreaders = NULL;
+}
+
+/*
+ * RCU torture up/down reader kthread, starting RCU readers in kthread
+ * context and ending them in hrtimer handlers. Otherwise similar to
+ * rcu_torture_reader().
+ */
+static int
+rcu_torture_updown(void *arg)
+{
+ int idx;
+ int rawidx;
+ struct rcu_torture_one_read_state_updown *rtorsup;
+ ktime_t t;
+
+ VERBOSE_TOROUT_STRING("rcu_torture_updown task started");
+ do {
+ for (rtorsup = updownreaders; rtorsup < &updownreaders[n_up_down]; rtorsup++) {
+ if (torture_must_stop())
+ break;
+ if (smp_load_acquire(&rtorsup->rtorsu_inuse))
+ continue;
+ init_rcu_torture_one_read_state(&rtorsup->rtorsu_rtors,
+ &rtorsup->rtorsu_trs);
+ rawidx = cur_ops->down_read();
+ idx = (rawidx << RCUTORTURE_RDR_SHIFT_1) & RCUTORTURE_RDR_MASK_1;
+ rtorsup->rtorsu_rtors.readstate = idx | RCUTORTURE_RDR_UPDOWN;
+ rtorsup->rtorsu_rtors.rtrsp++;
+ if (!rcu_torture_one_read_start(&rtorsup->rtorsu_rtors,
+ &rtorsup->rtorsu_trs, -1)) {
+ cur_ops->up_read(rawidx);
+ schedule_timeout_idle(HZ);
+ continue;
+ }
+ smp_store_release(&rtorsup->rtorsu_inuse, true);
+ t = torture_random(&rtorsup->rtorsu_trs) & 0xfffff; // One per million.
+ if (t < 10 * 1000)
+ t = 200 * 1000 * 1000;
+ hrtimer_start(&rtorsup->rtorsu_hrt, t,
+ HRTIMER_MODE_REL | HRTIMER_MODE_SOFT);
+ }
+ torture_hrtimeout_ms(1, 1000, &rcu_torture_updown_rand);
+ stutter_wait("rcu_torture_updown");
+ } while (!torture_must_stop());
+ rcu_torture_updown_cleanup();
+ torture_kthread_stopping("rcu_torture_updown");
+ return 0;
+}
+
/*
* Randomly Toggle CPUs' callback-offload state. This uses hrtimers to
* increase race probabilities and fuzzes the interval between toggling.
@@ -2620,7 +2802,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
"reader_flavor=%x "
"nocbs_nthreads=%d nocbs_toggle=%d "
"test_nmis=%d "
- "preempt_duration=%d preempt_interval=%d\n",
+ "preempt_duration=%d preempt_interval=%d n_up_down=%d\n",
torture_type, tag, nrealreaders, nrealfakewriters,
stat_interval, verbose, test_no_idle_hz, shuffle_interval,
stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
@@ -2634,7 +2816,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
reader_flavor,
nocbs_nthreads, nocbs_toggle,
test_nmis,
- preempt_duration, preempt_interval);
+ preempt_duration, preempt_interval, n_up_down);
}
static int rcutorture_booster_cleanup(unsigned int cpu)
@@ -3686,6 +3868,10 @@ rcu_torture_cleanup(void)
nocb_tasks = NULL;
}
+ if (updown_task) {
+ torture_stop_kthread(rcu_torture_updown, updown_task);
+ updown_task = NULL;
+ }
if (reader_tasks) {
for (i = 0; i < nrealreaders; i++)
torture_stop_kthread(rcu_torture_reader,
@@ -4216,6 +4402,9 @@ rcu_torture_init(void)
if (torture_init_error(firsterr))
goto unwind;
}
+ firsterr = rcu_torture_updown_init();
+ if (torture_init_error(firsterr))
+ goto unwind;
nrealnocbers = nocbs_nthreads;
if (WARN_ON(nrealnocbers < 0))
nrealnocbers = 1;
--
2.40.1>
> This commit adds a new rcutorture.n_up_down kernel boot parameter
> that specifies the number of outstanding SRCU up/down readers, which
> begin in kthread context and end in an hrtimer handler. There is a new
> kthread ("rcu_torture_updown") that scans an per-reader array looking
> for elements whose readers have ended. This kthread sleeps between one
> and two milliseconds between consecutive scans.
>
> [ paulmck: Apply kernel test robot feedback. ]
>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> ---
> kernel/rcu/rcutorture.c | 227 ++++++++++++++++++++++++++++++++++++----
> 1 file changed, 208 insertions(+), 19 deletions(-)
>
> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> index b0e96df636226..6afcd33e724ba 100644
> --- a/kernel/rcu/rcutorture.c
> +++ b/kernel/rcu/rcutorture.c
> @@ -55,22 +55,24 @@ MODULE_DESCRIPTION("Read-Copy Update module-based torture test facility");
> MODULE_LICENSE("GPL");
> MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
>
> -/* Bits for ->extendables field, extendables param, and related definitions. */
> -#define RCUTORTURE_RDR_SHIFT_1 8 /* Put SRCU index in upper bits. */
> -#define RCUTORTURE_RDR_MASK_1 (0xff << RCUTORTURE_RDR_SHIFT_1)
> -#define RCUTORTURE_RDR_SHIFT_2 16 /* Put SRCU index in upper bits. */
> -#define RCUTORTURE_RDR_MASK_2 (0xff << RCUTORTURE_RDR_SHIFT_2)
> -#define RCUTORTURE_RDR_BH 0x01 /* Extend readers by disabling bh. */
> -#define RCUTORTURE_RDR_IRQ 0x02 /* ... disabling interrupts. */
> -#define RCUTORTURE_RDR_PREEMPT 0x04 /* ... disabling preemption. */
> -#define RCUTORTURE_RDR_RBH 0x08 /* ... rcu_read_lock_bh(). */
> -#define RCUTORTURE_RDR_SCHED 0x10 /* ... rcu_read_lock_sched(). */
> -#define RCUTORTURE_RDR_RCU_1 0x20 /* ... entering another RCU reader. */
> -#define RCUTORTURE_RDR_RCU_2 0x40 /* ... entering another RCU reader. */
> -#define RCUTORTURE_RDR_NBITS 7 /* Number of bits defined above. */
> -#define RCUTORTURE_MAX_EXTEND \
> +// Bits for ->extendables field, extendables param, and related definitions.
> +#define RCUTORTURE_RDR_SHIFT_1 8 // Put SRCU index in upper bits.
> +#define RCUTORTURE_RDR_MASK_1 (0xff << RCUTORTURE_RDR_SHIFT_1)
> +#define RCUTORTURE_RDR_SHIFT_2 16 // Put SRCU index in upper bits.
> +#define RCUTORTURE_RDR_MASK_2 (0xff << RCUTORTURE_RDR_SHIFT_2)
> +#define RCUTORTURE_RDR_BH 0x01 // Extend readers by disabling bh.
> +#define RCUTORTURE_RDR_IRQ 0x02 // ... disabling interrupts.
> +#define RCUTORTURE_RDR_PREEMPT 0x04 // ... disabling preemption.
> +#define RCUTORTURE_RDR_RBH 0x08 // ... rcu_read_lock_bh().
> +#define RCUTORTURE_RDR_SCHED 0x10 // ... rcu_read_lock_sched().
> +#define RCUTORTURE_RDR_RCU_1 0x20 // ... entering another RCU reader.
> +#define RCUTORTURE_RDR_RCU_2 0x40 // ... entering another RCU reader.
> +#define RCUTORTURE_RDR_UPDOWN 0x80 // ... up-read from task, down-read from timer.
> + // Note: Manual start, automatic end.
> +#define RCUTORTURE_RDR_NBITS 8 // Number of bits defined above.
> +#define RCUTORTURE_MAX_EXTEND \
> (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
> - RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
> + RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED) // Intentionally omit RCUTORTURE_RDR_UPDOWN.
> #define RCUTORTURE_RDR_ALLBITS \
> (RCUTORTURE_MAX_EXTEND | RCUTORTURE_RDR_RCU_1 | RCUTORTURE_RDR_RCU_2 | \
> RCUTORTURE_RDR_MASK_1 | RCUTORTURE_RDR_MASK_2)
> @@ -110,6 +112,7 @@ torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
> torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
> torture_param(int, leakpointer, 0, "Leak pointer dereferences from readers");
> torture_param(int, n_barrier_cbs, 0, "# of callbacks/kthreads for barrier testing");
> +torture_param(int, n_up_down, 32, "# of concurrent up/down hrtimer-based RCU readers");
> torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
> torture_param(int, nreaders, -1, "Number of RCU reader threads");
> torture_param(int, object_debug, 0, "Enable debug-object double call_rcu() testing");
> @@ -152,6 +155,7 @@ static int nrealfakewriters;
> static struct task_struct *writer_task;
> static struct task_struct **fakewriter_tasks;
> static struct task_struct **reader_tasks;
> +static struct task_struct *updown_task;
> static struct task_struct **nocb_tasks;
> static struct task_struct *stats_task;
> static struct task_struct *fqs_task;
> @@ -374,6 +378,8 @@ struct rcu_torture_ops {
> void (*readunlock)(int idx);
> int (*readlock_held)(void); // lockdep.
> int (*readlock_nesting)(void); // actual nesting, if available, -1 if not.
> + int (*down_read)(void);
> + void (*up_read)(int idx);
> unsigned long (*get_gp_seq)(void);
> unsigned long (*gp_diff)(unsigned long new, unsigned long old);
> void (*deferred_free)(struct rcu_torture *p);
> @@ -421,6 +427,7 @@ struct rcu_torture_ops {
> int no_pi_lock;
> int debug_objects;
> int start_poll_irqsoff;
> + int have_up_down;
> const char *name;
> };
>
> @@ -754,6 +761,50 @@ static int torture_srcu_read_lock_held(void)
> return srcu_read_lock_held(srcu_ctlp);
> }
>
> +static bool srcu_torture_have_up_down(void)
> +{
> + int rf = reader_flavor;
> +
> + if (!rf)
> + rf = SRCU_READ_FLAVOR_NORMAL;
> + return !!(cur_ops->have_up_down & rf);
> +}
> +
> +static int srcu_torture_down_read(void)
> +{
> + int idx;
> + struct srcu_ctr __percpu *scp;
> +
> + WARN_ON_ONCE(reader_flavor & ~SRCU_READ_FLAVOR_ALL);
> + WARN_ON_ONCE(reader_flavor & (reader_flavor - 1));
> +
> + if ((reader_flavor & SRCU_READ_FLAVOR_NORMAL) || !(reader_flavor & SRCU_READ_FLAVOR_ALL)) {
> + idx = srcu_down_read(srcu_ctlp);
> + WARN_ON_ONCE(idx & ~0x1);
> + return idx;
> + }
> + if (reader_flavor & SRCU_READ_FLAVOR_FAST) {
> + scp = srcu_down_read_fast(srcu_ctlp);
> + idx = __srcu_ptr_to_ctr(srcu_ctlp, scp);
> + WARN_ON_ONCE(idx & ~0x1);
> + return idx << 3;
> + }
> + WARN_ON_ONCE(1);
> + return 0;
> +}
> +
> +static void srcu_torture_up_read(int idx)
> +{
> + WARN_ON_ONCE((reader_flavor && (idx & ~reader_flavor)) || (!reader_flavor && (idx & ~0x1)));
> + if (reader_flavor & SRCU_READ_FLAVOR_FAST)
> + srcu_up_read_fast(srcu_ctlp, __srcu_ctr_to_ptr(srcu_ctlp, (idx & 0x8) >> 3));
> + else if ((reader_flavor & SRCU_READ_FLAVOR_NORMAL) ||
> + !(reader_flavor & SRCU_READ_FLAVOR_ALL))
> + srcu_up_read(srcu_ctlp, idx & 0x1);
> + else
> + WARN_ON_ONCE(1);
> +}
> +
> static unsigned long srcu_torture_completed(void)
> {
> return srcu_batches_completed(srcu_ctlp);
> @@ -811,6 +862,8 @@ static struct rcu_torture_ops srcu_ops = {
> .readlock = srcu_torture_read_lock,
> .read_delay = srcu_read_delay,
> .readunlock = srcu_torture_read_unlock,
> + .down_read = srcu_torture_down_read,
> + .up_read = srcu_torture_up_read,
> .readlock_held = torture_srcu_read_lock_held,
> .get_gp_seq = srcu_torture_completed,
> .gp_diff = rcu_seq_diff,
> @@ -831,6 +884,8 @@ static struct rcu_torture_ops srcu_ops = {
> .irq_capable = 1,
> .no_pi_lock = IS_ENABLED(CONFIG_TINY_SRCU),
> .debug_objects = 1,
> + .have_up_down = IS_ENABLED(CONFIG_TINY_SRCU)
> + ? 0 : SRCU_READ_FLAVOR_NORMAL | SRCU_READ_FLAVOR_FAST,
> .name = "srcu"
> };
>
> @@ -856,6 +911,8 @@ static struct rcu_torture_ops srcud_ops = {
> .read_delay = srcu_read_delay,
> .readunlock = srcu_torture_read_unlock,
> .readlock_held = torture_srcu_read_lock_held,
> + .down_read = srcu_torture_down_read,
> + .up_read = srcu_torture_up_read,
> .get_gp_seq = srcu_torture_completed,
> .gp_diff = rcu_seq_diff,
> .deferred_free = srcu_torture_deferred_free,
> @@ -875,6 +932,8 @@ static struct rcu_torture_ops srcud_ops = {
> .irq_capable = 1,
> .no_pi_lock = IS_ENABLED(CONFIG_TINY_SRCU),
> .debug_objects = 1,
> + .have_up_down = IS_ENABLED(CONFIG_TINY_SRCU)
> + ? 0 : SRCU_READ_FLAVOR_NORMAL | SRCU_READ_FLAVOR_FAST,
> .name = "srcud"
> };
>
> @@ -1985,7 +2044,7 @@ static void rcutorture_one_extend(int *readstate, int newstate, bool insoftirq,
>
> first = idxold1 == 0;
> WARN_ON_ONCE(idxold2 < 0);
> - WARN_ON_ONCE(idxold2 & ~RCUTORTURE_RDR_ALLBITS);
> + WARN_ON_ONCE(idxold2 & ~(RCUTORTURE_RDR_ALLBITS | RCUTORTURE_RDR_UPDOWN));
> rcutorture_one_extend_check("before change", idxold1, statesnew, statesold, insoftirq);
> rtrsp->rt_readstate = newstate;
>
> @@ -2061,6 +2120,11 @@ static void rcutorture_one_extend(int *readstate, int newstate, bool insoftirq,
> if (lockit)
> raw_spin_unlock_irqrestore(¤t->pi_lock, flags);
> }
> + if (statesold & RCUTORTURE_RDR_UPDOWN) {
> + cur_ops->up_read((idxold1 & RCUTORTURE_RDR_MASK_1) >> RCUTORTURE_RDR_SHIFT_1);
> + WARN_ON_ONCE(idxnew1 != -1);
> + idxold1 = 0;
> + }
>
> /* Delay if neither beginning nor end and there was a change. */
> if ((statesnew || statesold) && *readstate && newstate)
> @@ -2201,7 +2265,8 @@ static bool rcu_torture_one_read_start(struct rcu_torture_one_read_state *rtorsp
> rtorsp->started = cur_ops->get_gp_seq();
> rtorsp->ts = rcu_trace_clock_local();
> rtorsp->p = rcu_dereference_check(rcu_torture_current,
> - !cur_ops->readlock_held || cur_ops->readlock_held());
> + !cur_ops->readlock_held || cur_ops->readlock_held() ||
> + (rtorsp->readstate & RCUTORTURE_RDR_UPDOWN));
> if (rtorsp->p == NULL) {
> /* Wait for rcu_torture_writer to get underway */
> rcutorture_one_extend(&rtorsp->readstate, 0, myid < 0, trsp, rtorsp->rtrsp);
> @@ -2370,6 +2435,123 @@ rcu_torture_reader(void *arg)
> return 0;
> }
>
> +struct rcu_torture_one_read_state_updown {
> + struct hrtimer rtorsu_hrt;
> + bool rtorsu_inuse;
> + struct torture_random_state rtorsu_trs;
> + struct rcu_torture_one_read_state rtorsu_rtors;
> +};
> +
> +static struct rcu_torture_one_read_state_updown *updownreaders;
> +static DEFINE_TORTURE_RANDOM(rcu_torture_updown_rand);
> +static int rcu_torture_updown(void *arg);
> +
> +static enum hrtimer_restart rcu_torture_updown_hrt(struct hrtimer *hrtp)
> +{
> + struct rcu_torture_one_read_state_updown *rtorsup;
> +
> + rtorsup = container_of(hrtp, struct rcu_torture_one_read_state_updown, rtorsu_hrt);
> + rcu_torture_one_read_end(&rtorsup->rtorsu_rtors, &rtorsup->rtorsu_trs, -1);
> + smp_store_release(&rtorsup->rtorsu_inuse, false);
> + return HRTIMER_NORESTART;
> +}
> +
> +static int rcu_torture_updown_init(void)
> +{
> + int i;
> + struct torture_random_state *rand = &rcu_torture_updown_rand;
> + int ret;
> +
> + if (n_up_down < 0)
> + return 0;
> + if (!srcu_torture_have_up_down()) {
> + VERBOSE_TOROUT_STRING("rcu_torture_updown_init: Disabling up/down reader tests due to lack of primitives");
> + return 0;
> + }
> + updownreaders = kcalloc(n_up_down, sizeof(*updownreaders), GFP_KERNEL);
> + if (!updownreaders) {
> + VERBOSE_TOROUT_STRING("rcu_torture_updown_init: Out of memory, disabling up/down reader tests");
> + return -ENOMEM;
> + }
> + for (i = 0; i < n_up_down; i++) {
> + init_rcu_torture_one_read_state(&updownreaders[i].rtorsu_rtors, rand);
> + hrtimer_init(&updownreaders[i].rtorsu_hrt, CLOCK_MONOTONIC,
> + HRTIMER_MODE_REL | HRTIMER_MODE_SOFT);
> + updownreaders[i].rtorsu_hrt.function = rcu_torture_updown_hrt;
> + torture_random_init(&updownreaders[i].rtorsu_trs);
> + init_rcu_torture_one_read_state(&updownreaders[i].rtorsu_rtors,
> + &updownreaders[i].rtorsu_trs);
> + }
> + ret = torture_create_kthread(rcu_torture_updown, rand, updown_task);
> + if (ret) {
> + kfree(updownreaders);
> + updownreaders = NULL;
> + }
> + return ret;
> +}
> +
> +static void rcu_torture_updown_cleanup(void)
> +{
> + struct rcu_torture_one_read_state_updown *rtorsup;
> +
> + for (rtorsup = updownreaders; rtorsup < &updownreaders[n_up_down]; rtorsup++) {
> + if (!smp_load_acquire(&rtorsup->rtorsu_inuse))
> + continue;
> + (void)hrtimer_cancel(&rtorsup->rtorsu_hrt);
> + WARN_ON_ONCE(rtorsup->rtorsu_inuse);
Hello, Paul
When I rmmod rcutorture, the following warning is triggered:
[ 809.227012] WARNING: CPU: 7 PID: 662 at
kernel/rcu/rcutorture.c:2506 rcu_torture_updown+0x3ff/0x620
[rcutorture]
[ 809.227038] Modules linked in: rcutorture(-) torture [last
unloaded: rcutorture]
[ 809.227052] CPU: 7 UID: 0 PID: 662 Comm: rcu_torture_upd Not
tainted 6.14.0-rc1-yoctodev-standard+ #103
f927b67579e64efac707898e59c492a894becb07
[ 809.227057] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 809.227061] RIP: 0010:rcu_torture_updown+0x3ff/0x620 [rcutorture]
[ 809.227112] Call Trace:
[ 809.227114] <TASK>
[ 809.227118] ? show_regs+0x65/0x70
[ 809.227127] ? __warn+0xd5/0x310
[ 809.227137] ? rcu_torture_updown+0x3ff/0x620 [rcutorture
1eb1c0a0090f471c5e98b34f024c9030cef829ed]
[ 809.227155] ? report_bug+0x23e/0x490
[ 809.227172] ? handle_bug+0x5b/0xa0
[ 809.227180] ? exc_invalid_op+0x1c/0x50
[ 809.227188] ? asm_exc_invalid_op+0x1f/0x30
[ 809.227210] ? hrtimer_try_to_cancel+0x160/0x490
[ 809.227216] ? _raw_spin_unlock_irqrestore+0x4a/0x80
[ 809.227225] ? rcu_torture_updown+0x3ff/0x620 [rcutorture
1eb1c0a0090f471c5e98b34f024c9030cef829ed]
[ 809.227255] ? rcu_torture_updown+0x340/0x620 [rcutorture
1eb1c0a0090f471c5e98b34f024c9030cef829ed]
[ 809.227320] ? __pfx_rcu_torture_updown+0x10/0x10 [rcutorture
1eb1c0a0090f471c5e98b34f024c9030cef829ed]
[ 809.227337] kthread+0x3d9/0x810
[ 809.227349] ? __pfx_kthread+0x10/0x10
[ 809.227357] ? rt_spin_unlock+0x4c/0x90
[ 809.227362] ? rt_spin_unlock+0x4c/0x90
[ 809.227367] ? calculate_sigpending+0x88/0xa0
[ 809.227372] ? __pfx_kthread+0x10/0x10
[ 809.227380] ret_from_fork+0x40/0x70
[ 809.227383] ? __pfx_kthread+0x10/0x10
[ 809.227390] ret_from_fork_asm+0x1a/0x30
[ 809.227420] </TASK>
If rtorsu_hrt timer is still in timer_queue, invoke hrtimer_cancel() will
remove it from timerqueue and directly return, so the rcu_torture_updown_hrt()
will not be executed and the rtorsup->rtorsu_inuse cannot be set false.
How about modifying it as follows:
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 04d7a2173b95..ecf3d3797f7e 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2502,8 +2502,7 @@ static void rcu_torture_updown_cleanup(void)
for (rtorsup = updownreaders; rtorsup <
&updownreaders[n_up_down]; rtorsup++) {
if (!smp_load_acquire(&rtorsup->rtorsu_inuse))
continue;
- (void)hrtimer_cancel(&rtorsup->rtorsu_hrt);
- if (WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
+ if (hrtimer_cancel(&rtorsup->rtorsu_hrt) ||
WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
rcu_torture_one_read_end(&rtorsup->rtorsu_rtors, &rtorsup->rtorsu_trs,
-1);
WARN_ONCE(rtorsup->rtorsu_nups >=
rtorsup->rtorsu_ndowns, "%s: Up without matching down #%zu.\n",
__func__, rtorsup - updownreaders);
rtorsup->rtorsu_nups++;
Thanks
Zqiang
> +
> + }
> + kfree(updownreaders);
> + updownreaders = NULL;
> +}
> +
> +/*
> + * RCU torture up/down reader kthread, starting RCU readers in kthread
> + * context and ending them in hrtimer handlers. Otherwise similar to
> + * rcu_torture_reader().
> + */
> +static int
> +rcu_torture_updown(void *arg)
> +{
> + int idx;
> + int rawidx;
> + struct rcu_torture_one_read_state_updown *rtorsup;
> + ktime_t t;
> +
> + VERBOSE_TOROUT_STRING("rcu_torture_updown task started");
> + do {
> + for (rtorsup = updownreaders; rtorsup < &updownreaders[n_up_down]; rtorsup++) {
> + if (torture_must_stop())
> + break;
> + if (smp_load_acquire(&rtorsup->rtorsu_inuse))
> + continue;
> + init_rcu_torture_one_read_state(&rtorsup->rtorsu_rtors,
> + &rtorsup->rtorsu_trs);
> + rawidx = cur_ops->down_read();
> + idx = (rawidx << RCUTORTURE_RDR_SHIFT_1) & RCUTORTURE_RDR_MASK_1;
> + rtorsup->rtorsu_rtors.readstate = idx | RCUTORTURE_RDR_UPDOWN;
> + rtorsup->rtorsu_rtors.rtrsp++;
> + if (!rcu_torture_one_read_start(&rtorsup->rtorsu_rtors,
> + &rtorsup->rtorsu_trs, -1)) {
> + cur_ops->up_read(rawidx);
> + schedule_timeout_idle(HZ);
> + continue;
> + }
> + smp_store_release(&rtorsup->rtorsu_inuse, true);
> + t = torture_random(&rtorsup->rtorsu_trs) & 0xfffff; // One per million.
> + if (t < 10 * 1000)
> + t = 200 * 1000 * 1000;
> + hrtimer_start(&rtorsup->rtorsu_hrt, t,
> + HRTIMER_MODE_REL | HRTIMER_MODE_SOFT);
> + }
> + torture_hrtimeout_ms(1, 1000, &rcu_torture_updown_rand);
> + stutter_wait("rcu_torture_updown");
> + } while (!torture_must_stop());
> + rcu_torture_updown_cleanup();
> + torture_kthread_stopping("rcu_torture_updown");
> + return 0;
> +}
> +
> /*
> * Randomly Toggle CPUs' callback-offload state. This uses hrtimers to
> * increase race probabilities and fuzzes the interval between toggling.
> @@ -2620,7 +2802,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
> "reader_flavor=%x "
> "nocbs_nthreads=%d nocbs_toggle=%d "
> "test_nmis=%d "
> - "preempt_duration=%d preempt_interval=%d\n",
> + "preempt_duration=%d preempt_interval=%d n_up_down=%d\n",
> torture_type, tag, nrealreaders, nrealfakewriters,
> stat_interval, verbose, test_no_idle_hz, shuffle_interval,
> stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
> @@ -2634,7 +2816,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
> reader_flavor,
> nocbs_nthreads, nocbs_toggle,
> test_nmis,
> - preempt_duration, preempt_interval);
> + preempt_duration, preempt_interval, n_up_down);
> }
>
> static int rcutorture_booster_cleanup(unsigned int cpu)
> @@ -3686,6 +3868,10 @@ rcu_torture_cleanup(void)
> nocb_tasks = NULL;
> }
>
> + if (updown_task) {
> + torture_stop_kthread(rcu_torture_updown, updown_task);
> + updown_task = NULL;
> + }
> if (reader_tasks) {
> for (i = 0; i < nrealreaders; i++)
> torture_stop_kthread(rcu_torture_reader,
> @@ -4216,6 +4402,9 @@ rcu_torture_init(void)
> if (torture_init_error(firsterr))
> goto unwind;
> }
> + firsterr = rcu_torture_updown_init();
> + if (torture_init_error(firsterr))
> + goto unwind;
> nrealnocbers = nocbs_nthreads;
> if (WARN_ON(nrealnocbers < 0))
> nrealnocbers = 1;
> --
> 2.40.1
>
>
On Thu, Mar 27, 2025 at 11:26:01AM +0800, Z qiang wrote:
> >
> > This commit adds a new rcutorture.n_up_down kernel boot parameter
> > that specifies the number of outstanding SRCU up/down readers, which
> > begin in kthread context and end in an hrtimer handler. There is a new
> > kthread ("rcu_torture_updown") that scans an per-reader array looking
> > for elements whose readers have ended. This kthread sleeps between one
> > and two milliseconds between consecutive scans.
> >
> > [ paulmck: Apply kernel test robot feedback. ]
> >
> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> > ---
> > kernel/rcu/rcutorture.c | 227 ++++++++++++++++++++++++++++++++++++----
> > 1 file changed, 208 insertions(+), 19 deletions(-)
> >
> > diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> > index b0e96df636226..6afcd33e724ba 100644
> > --- a/kernel/rcu/rcutorture.c
> > +++ b/kernel/rcu/rcutorture.c
> > @@ -55,22 +55,24 @@ MODULE_DESCRIPTION("Read-Copy Update module-based torture test facility");
> > MODULE_LICENSE("GPL");
> > MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
> >
> > -/* Bits for ->extendables field, extendables param, and related definitions. */
> > -#define RCUTORTURE_RDR_SHIFT_1 8 /* Put SRCU index in upper bits. */
> > -#define RCUTORTURE_RDR_MASK_1 (0xff << RCUTORTURE_RDR_SHIFT_1)
> > -#define RCUTORTURE_RDR_SHIFT_2 16 /* Put SRCU index in upper bits. */
> > -#define RCUTORTURE_RDR_MASK_2 (0xff << RCUTORTURE_RDR_SHIFT_2)
> > -#define RCUTORTURE_RDR_BH 0x01 /* Extend readers by disabling bh. */
> > -#define RCUTORTURE_RDR_IRQ 0x02 /* ... disabling interrupts. */
> > -#define RCUTORTURE_RDR_PREEMPT 0x04 /* ... disabling preemption. */
> > -#define RCUTORTURE_RDR_RBH 0x08 /* ... rcu_read_lock_bh(). */
> > -#define RCUTORTURE_RDR_SCHED 0x10 /* ... rcu_read_lock_sched(). */
> > -#define RCUTORTURE_RDR_RCU_1 0x20 /* ... entering another RCU reader. */
> > -#define RCUTORTURE_RDR_RCU_2 0x40 /* ... entering another RCU reader. */
> > -#define RCUTORTURE_RDR_NBITS 7 /* Number of bits defined above. */
> > -#define RCUTORTURE_MAX_EXTEND \
> > +// Bits for ->extendables field, extendables param, and related definitions.
> > +#define RCUTORTURE_RDR_SHIFT_1 8 // Put SRCU index in upper bits.
> > +#define RCUTORTURE_RDR_MASK_1 (0xff << RCUTORTURE_RDR_SHIFT_1)
> > +#define RCUTORTURE_RDR_SHIFT_2 16 // Put SRCU index in upper bits.
> > +#define RCUTORTURE_RDR_MASK_2 (0xff << RCUTORTURE_RDR_SHIFT_2)
> > +#define RCUTORTURE_RDR_BH 0x01 // Extend readers by disabling bh.
> > +#define RCUTORTURE_RDR_IRQ 0x02 // ... disabling interrupts.
> > +#define RCUTORTURE_RDR_PREEMPT 0x04 // ... disabling preemption.
> > +#define RCUTORTURE_RDR_RBH 0x08 // ... rcu_read_lock_bh().
> > +#define RCUTORTURE_RDR_SCHED 0x10 // ... rcu_read_lock_sched().
> > +#define RCUTORTURE_RDR_RCU_1 0x20 // ... entering another RCU reader.
> > +#define RCUTORTURE_RDR_RCU_2 0x40 // ... entering another RCU reader.
> > +#define RCUTORTURE_RDR_UPDOWN 0x80 // ... up-read from task, down-read from timer.
> > + // Note: Manual start, automatic end.
> > +#define RCUTORTURE_RDR_NBITS 8 // Number of bits defined above.
> > +#define RCUTORTURE_MAX_EXTEND \
> > (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
> > - RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
> > + RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED) // Intentionally omit RCUTORTURE_RDR_UPDOWN.
> > #define RCUTORTURE_RDR_ALLBITS \
> > (RCUTORTURE_MAX_EXTEND | RCUTORTURE_RDR_RCU_1 | RCUTORTURE_RDR_RCU_2 | \
> > RCUTORTURE_RDR_MASK_1 | RCUTORTURE_RDR_MASK_2)
> > @@ -110,6 +112,7 @@ torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
> > torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
> > torture_param(int, leakpointer, 0, "Leak pointer dereferences from readers");
> > torture_param(int, n_barrier_cbs, 0, "# of callbacks/kthreads for barrier testing");
> > +torture_param(int, n_up_down, 32, "# of concurrent up/down hrtimer-based RCU readers");
> > torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
> > torture_param(int, nreaders, -1, "Number of RCU reader threads");
> > torture_param(int, object_debug, 0, "Enable debug-object double call_rcu() testing");
> > @@ -152,6 +155,7 @@ static int nrealfakewriters;
> > static struct task_struct *writer_task;
> > static struct task_struct **fakewriter_tasks;
> > static struct task_struct **reader_tasks;
> > +static struct task_struct *updown_task;
> > static struct task_struct **nocb_tasks;
> > static struct task_struct *stats_task;
> > static struct task_struct *fqs_task;
> > @@ -374,6 +378,8 @@ struct rcu_torture_ops {
> > void (*readunlock)(int idx);
> > int (*readlock_held)(void); // lockdep.
> > int (*readlock_nesting)(void); // actual nesting, if available, -1 if not.
> > + int (*down_read)(void);
> > + void (*up_read)(int idx);
> > unsigned long (*get_gp_seq)(void);
> > unsigned long (*gp_diff)(unsigned long new, unsigned long old);
> > void (*deferred_free)(struct rcu_torture *p);
> > @@ -421,6 +427,7 @@ struct rcu_torture_ops {
> > int no_pi_lock;
> > int debug_objects;
> > int start_poll_irqsoff;
> > + int have_up_down;
> > const char *name;
> > };
> >
> > @@ -754,6 +761,50 @@ static int torture_srcu_read_lock_held(void)
> > return srcu_read_lock_held(srcu_ctlp);
> > }
> >
> > +static bool srcu_torture_have_up_down(void)
> > +{
> > + int rf = reader_flavor;
> > +
> > + if (!rf)
> > + rf = SRCU_READ_FLAVOR_NORMAL;
> > + return !!(cur_ops->have_up_down & rf);
> > +}
> > +
> > +static int srcu_torture_down_read(void)
> > +{
> > + int idx;
> > + struct srcu_ctr __percpu *scp;
> > +
> > + WARN_ON_ONCE(reader_flavor & ~SRCU_READ_FLAVOR_ALL);
> > + WARN_ON_ONCE(reader_flavor & (reader_flavor - 1));
> > +
> > + if ((reader_flavor & SRCU_READ_FLAVOR_NORMAL) || !(reader_flavor & SRCU_READ_FLAVOR_ALL)) {
> > + idx = srcu_down_read(srcu_ctlp);
> > + WARN_ON_ONCE(idx & ~0x1);
> > + return idx;
> > + }
> > + if (reader_flavor & SRCU_READ_FLAVOR_FAST) {
> > + scp = srcu_down_read_fast(srcu_ctlp);
> > + idx = __srcu_ptr_to_ctr(srcu_ctlp, scp);
> > + WARN_ON_ONCE(idx & ~0x1);
> > + return idx << 3;
> > + }
> > + WARN_ON_ONCE(1);
> > + return 0;
> > +}
> > +
> > +static void srcu_torture_up_read(int idx)
> > +{
> > + WARN_ON_ONCE((reader_flavor && (idx & ~reader_flavor)) || (!reader_flavor && (idx & ~0x1)));
> > + if (reader_flavor & SRCU_READ_FLAVOR_FAST)
> > + srcu_up_read_fast(srcu_ctlp, __srcu_ctr_to_ptr(srcu_ctlp, (idx & 0x8) >> 3));
> > + else if ((reader_flavor & SRCU_READ_FLAVOR_NORMAL) ||
> > + !(reader_flavor & SRCU_READ_FLAVOR_ALL))
> > + srcu_up_read(srcu_ctlp, idx & 0x1);
> > + else
> > + WARN_ON_ONCE(1);
> > +}
> > +
> > static unsigned long srcu_torture_completed(void)
> > {
> > return srcu_batches_completed(srcu_ctlp);
> > @@ -811,6 +862,8 @@ static struct rcu_torture_ops srcu_ops = {
> > .readlock = srcu_torture_read_lock,
> > .read_delay = srcu_read_delay,
> > .readunlock = srcu_torture_read_unlock,
> > + .down_read = srcu_torture_down_read,
> > + .up_read = srcu_torture_up_read,
> > .readlock_held = torture_srcu_read_lock_held,
> > .get_gp_seq = srcu_torture_completed,
> > .gp_diff = rcu_seq_diff,
> > @@ -831,6 +884,8 @@ static struct rcu_torture_ops srcu_ops = {
> > .irq_capable = 1,
> > .no_pi_lock = IS_ENABLED(CONFIG_TINY_SRCU),
> > .debug_objects = 1,
> > + .have_up_down = IS_ENABLED(CONFIG_TINY_SRCU)
> > + ? 0 : SRCU_READ_FLAVOR_NORMAL | SRCU_READ_FLAVOR_FAST,
> > .name = "srcu"
> > };
> >
> > @@ -856,6 +911,8 @@ static struct rcu_torture_ops srcud_ops = {
> > .read_delay = srcu_read_delay,
> > .readunlock = srcu_torture_read_unlock,
> > .readlock_held = torture_srcu_read_lock_held,
> > + .down_read = srcu_torture_down_read,
> > + .up_read = srcu_torture_up_read,
> > .get_gp_seq = srcu_torture_completed,
> > .gp_diff = rcu_seq_diff,
> > .deferred_free = srcu_torture_deferred_free,
> > @@ -875,6 +932,8 @@ static struct rcu_torture_ops srcud_ops = {
> > .irq_capable = 1,
> > .no_pi_lock = IS_ENABLED(CONFIG_TINY_SRCU),
> > .debug_objects = 1,
> > + .have_up_down = IS_ENABLED(CONFIG_TINY_SRCU)
> > + ? 0 : SRCU_READ_FLAVOR_NORMAL | SRCU_READ_FLAVOR_FAST,
> > .name = "srcud"
> > };
> >
> > @@ -1985,7 +2044,7 @@ static void rcutorture_one_extend(int *readstate, int newstate, bool insoftirq,
> >
> > first = idxold1 == 0;
> > WARN_ON_ONCE(idxold2 < 0);
> > - WARN_ON_ONCE(idxold2 & ~RCUTORTURE_RDR_ALLBITS);
> > + WARN_ON_ONCE(idxold2 & ~(RCUTORTURE_RDR_ALLBITS | RCUTORTURE_RDR_UPDOWN));
> > rcutorture_one_extend_check("before change", idxold1, statesnew, statesold, insoftirq);
> > rtrsp->rt_readstate = newstate;
> >
> > @@ -2061,6 +2120,11 @@ static void rcutorture_one_extend(int *readstate, int newstate, bool insoftirq,
> > if (lockit)
> > raw_spin_unlock_irqrestore(¤t->pi_lock, flags);
> > }
> > + if (statesold & RCUTORTURE_RDR_UPDOWN) {
> > + cur_ops->up_read((idxold1 & RCUTORTURE_RDR_MASK_1) >> RCUTORTURE_RDR_SHIFT_1);
> > + WARN_ON_ONCE(idxnew1 != -1);
> > + idxold1 = 0;
> > + }
> >
> > /* Delay if neither beginning nor end and there was a change. */
> > if ((statesnew || statesold) && *readstate && newstate)
> > @@ -2201,7 +2265,8 @@ static bool rcu_torture_one_read_start(struct rcu_torture_one_read_state *rtorsp
> > rtorsp->started = cur_ops->get_gp_seq();
> > rtorsp->ts = rcu_trace_clock_local();
> > rtorsp->p = rcu_dereference_check(rcu_torture_current,
> > - !cur_ops->readlock_held || cur_ops->readlock_held());
> > + !cur_ops->readlock_held || cur_ops->readlock_held() ||
> > + (rtorsp->readstate & RCUTORTURE_RDR_UPDOWN));
> > if (rtorsp->p == NULL) {
> > /* Wait for rcu_torture_writer to get underway */
> > rcutorture_one_extend(&rtorsp->readstate, 0, myid < 0, trsp, rtorsp->rtrsp);
> > @@ -2370,6 +2435,123 @@ rcu_torture_reader(void *arg)
> > return 0;
> > }
> >
> > +struct rcu_torture_one_read_state_updown {
> > + struct hrtimer rtorsu_hrt;
> > + bool rtorsu_inuse;
> > + struct torture_random_state rtorsu_trs;
> > + struct rcu_torture_one_read_state rtorsu_rtors;
> > +};
> > +
> > +static struct rcu_torture_one_read_state_updown *updownreaders;
> > +static DEFINE_TORTURE_RANDOM(rcu_torture_updown_rand);
> > +static int rcu_torture_updown(void *arg);
> > +
> > +static enum hrtimer_restart rcu_torture_updown_hrt(struct hrtimer *hrtp)
> > +{
> > + struct rcu_torture_one_read_state_updown *rtorsup;
> > +
> > + rtorsup = container_of(hrtp, struct rcu_torture_one_read_state_updown, rtorsu_hrt);
> > + rcu_torture_one_read_end(&rtorsup->rtorsu_rtors, &rtorsup->rtorsu_trs, -1);
> > + smp_store_release(&rtorsup->rtorsu_inuse, false);
> > + return HRTIMER_NORESTART;
> > +}
> > +
> > +static int rcu_torture_updown_init(void)
> > +{
> > + int i;
> > + struct torture_random_state *rand = &rcu_torture_updown_rand;
> > + int ret;
> > +
> > + if (n_up_down < 0)
> > + return 0;
> > + if (!srcu_torture_have_up_down()) {
> > + VERBOSE_TOROUT_STRING("rcu_torture_updown_init: Disabling up/down reader tests due to lack of primitives");
> > + return 0;
> > + }
> > + updownreaders = kcalloc(n_up_down, sizeof(*updownreaders), GFP_KERNEL);
> > + if (!updownreaders) {
> > + VERBOSE_TOROUT_STRING("rcu_torture_updown_init: Out of memory, disabling up/down reader tests");
> > + return -ENOMEM;
> > + }
> > + for (i = 0; i < n_up_down; i++) {
> > + init_rcu_torture_one_read_state(&updownreaders[i].rtorsu_rtors, rand);
> > + hrtimer_init(&updownreaders[i].rtorsu_hrt, CLOCK_MONOTONIC,
> > + HRTIMER_MODE_REL | HRTIMER_MODE_SOFT);
> > + updownreaders[i].rtorsu_hrt.function = rcu_torture_updown_hrt;
> > + torture_random_init(&updownreaders[i].rtorsu_trs);
> > + init_rcu_torture_one_read_state(&updownreaders[i].rtorsu_rtors,
> > + &updownreaders[i].rtorsu_trs);
> > + }
> > + ret = torture_create_kthread(rcu_torture_updown, rand, updown_task);
> > + if (ret) {
> > + kfree(updownreaders);
> > + updownreaders = NULL;
> > + }
> > + return ret;
> > +}
> > +
> > +static void rcu_torture_updown_cleanup(void)
> > +{
> > + struct rcu_torture_one_read_state_updown *rtorsup;
> > +
> > + for (rtorsup = updownreaders; rtorsup < &updownreaders[n_up_down]; rtorsup++) {
> > + if (!smp_load_acquire(&rtorsup->rtorsu_inuse))
> > + continue;
> > + (void)hrtimer_cancel(&rtorsup->rtorsu_hrt);
> > + WARN_ON_ONCE(rtorsup->rtorsu_inuse);
>
> Hello, Paul
>
> When I rmmod rcutorture, the following warning is triggered:
>
> [ 809.227012] WARNING: CPU: 7 PID: 662 at
> kernel/rcu/rcutorture.c:2506 rcu_torture_updown+0x3ff/0x620
> [rcutorture]
> [ 809.227038] Modules linked in: rcutorture(-) torture [last
> unloaded: rcutorture]
> [ 809.227052] CPU: 7 UID: 0 PID: 662 Comm: rcu_torture_upd Not
> tainted 6.14.0-rc1-yoctodev-standard+ #103
> f927b67579e64efac707898e59c492a894becb07
> [ 809.227057] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
> BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
> [ 809.227061] RIP: 0010:rcu_torture_updown+0x3ff/0x620 [rcutorture]
> [ 809.227112] Call Trace:
> [ 809.227114] <TASK>
> [ 809.227118] ? show_regs+0x65/0x70
> [ 809.227127] ? __warn+0xd5/0x310
> [ 809.227137] ? rcu_torture_updown+0x3ff/0x620 [rcutorture
> 1eb1c0a0090f471c5e98b34f024c9030cef829ed]
> [ 809.227155] ? report_bug+0x23e/0x490
> [ 809.227172] ? handle_bug+0x5b/0xa0
> [ 809.227180] ? exc_invalid_op+0x1c/0x50
> [ 809.227188] ? asm_exc_invalid_op+0x1f/0x30
> [ 809.227210] ? hrtimer_try_to_cancel+0x160/0x490
> [ 809.227216] ? _raw_spin_unlock_irqrestore+0x4a/0x80
> [ 809.227225] ? rcu_torture_updown+0x3ff/0x620 [rcutorture
> 1eb1c0a0090f471c5e98b34f024c9030cef829ed]
> [ 809.227255] ? rcu_torture_updown+0x340/0x620 [rcutorture
> 1eb1c0a0090f471c5e98b34f024c9030cef829ed]
> [ 809.227320] ? __pfx_rcu_torture_updown+0x10/0x10 [rcutorture
> 1eb1c0a0090f471c5e98b34f024c9030cef829ed]
> [ 809.227337] kthread+0x3d9/0x810
> [ 809.227349] ? __pfx_kthread+0x10/0x10
> [ 809.227357] ? rt_spin_unlock+0x4c/0x90
> [ 809.227362] ? rt_spin_unlock+0x4c/0x90
> [ 809.227367] ? calculate_sigpending+0x88/0xa0
> [ 809.227372] ? __pfx_kthread+0x10/0x10
> [ 809.227380] ret_from_fork+0x40/0x70
> [ 809.227383] ? __pfx_kthread+0x10/0x10
> [ 809.227390] ret_from_fork_asm+0x1a/0x30
> [ 809.227420] </TASK>
>
> If rtorsu_hrt timer is still in timer_queue, invoke hrtimer_cancel() will
> remove it from timerqueue and directly return, so the rcu_torture_updown_hrt()
> will not be executed and the rtorsup->rtorsu_inuse cannot be set false.
>
> How about modifying it as follows:
>
> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> index 04d7a2173b95..ecf3d3797f7e 100644
> --- a/kernel/rcu/rcutorture.c
> +++ b/kernel/rcu/rcutorture.c
> @@ -2502,8 +2502,7 @@ static void rcu_torture_updown_cleanup(void)
> for (rtorsup = updownreaders; rtorsup <
> &updownreaders[n_up_down]; rtorsup++) {
> if (!smp_load_acquire(&rtorsup->rtorsu_inuse))
> continue;
> - (void)hrtimer_cancel(&rtorsup->rtorsu_hrt);
> - if (WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
> + if (hrtimer_cancel(&rtorsup->rtorsu_hrt) ||
> WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
>
> rcu_torture_one_read_end(&rtorsup->rtorsu_rtors, &rtorsup->rtorsu_trs,
> -1);
> WARN_ONCE(rtorsup->rtorsu_nups >=
> rtorsup->rtorsu_ndowns, "%s: Up without matching down #%zu.\n",
> __func__, rtorsup - updownreaders);
> rtorsup->rtorsu_nups++;
Good eyes, thank you! I have applied this fix with attribution.
Thanx, Paul
> Thanks
> Zqiang
>
> > +
> > + }
> > + kfree(updownreaders);
> > + updownreaders = NULL;
> > +}
> > +
> > +/*
> > + * RCU torture up/down reader kthread, starting RCU readers in kthread
> > + * context and ending them in hrtimer handlers. Otherwise similar to
> > + * rcu_torture_reader().
> > + */
> > +static int
> > +rcu_torture_updown(void *arg)
> > +{
> > + int idx;
> > + int rawidx;
> > + struct rcu_torture_one_read_state_updown *rtorsup;
> > + ktime_t t;
> > +
> > + VERBOSE_TOROUT_STRING("rcu_torture_updown task started");
> > + do {
> > + for (rtorsup = updownreaders; rtorsup < &updownreaders[n_up_down]; rtorsup++) {
> > + if (torture_must_stop())
> > + break;
> > + if (smp_load_acquire(&rtorsup->rtorsu_inuse))
> > + continue;
> > + init_rcu_torture_one_read_state(&rtorsup->rtorsu_rtors,
> > + &rtorsup->rtorsu_trs);
> > + rawidx = cur_ops->down_read();
> > + idx = (rawidx << RCUTORTURE_RDR_SHIFT_1) & RCUTORTURE_RDR_MASK_1;
> > + rtorsup->rtorsu_rtors.readstate = idx | RCUTORTURE_RDR_UPDOWN;
> > + rtorsup->rtorsu_rtors.rtrsp++;
> > + if (!rcu_torture_one_read_start(&rtorsup->rtorsu_rtors,
> > + &rtorsup->rtorsu_trs, -1)) {
> > + cur_ops->up_read(rawidx);
> > + schedule_timeout_idle(HZ);
> > + continue;
> > + }
> > + smp_store_release(&rtorsup->rtorsu_inuse, true);
> > + t = torture_random(&rtorsup->rtorsu_trs) & 0xfffff; // One per million.
> > + if (t < 10 * 1000)
> > + t = 200 * 1000 * 1000;
> > + hrtimer_start(&rtorsup->rtorsu_hrt, t,
> > + HRTIMER_MODE_REL | HRTIMER_MODE_SOFT);
> > + }
> > + torture_hrtimeout_ms(1, 1000, &rcu_torture_updown_rand);
> > + stutter_wait("rcu_torture_updown");
> > + } while (!torture_must_stop());
> > + rcu_torture_updown_cleanup();
> > + torture_kthread_stopping("rcu_torture_updown");
> > + return 0;
> > +}
> > +
> > /*
> > * Randomly Toggle CPUs' callback-offload state. This uses hrtimers to
> > * increase race probabilities and fuzzes the interval between toggling.
> > @@ -2620,7 +2802,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
> > "reader_flavor=%x "
> > "nocbs_nthreads=%d nocbs_toggle=%d "
> > "test_nmis=%d "
> > - "preempt_duration=%d preempt_interval=%d\n",
> > + "preempt_duration=%d preempt_interval=%d n_up_down=%d\n",
> > torture_type, tag, nrealreaders, nrealfakewriters,
> > stat_interval, verbose, test_no_idle_hz, shuffle_interval,
> > stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
> > @@ -2634,7 +2816,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
> > reader_flavor,
> > nocbs_nthreads, nocbs_toggle,
> > test_nmis,
> > - preempt_duration, preempt_interval);
> > + preempt_duration, preempt_interval, n_up_down);
> > }
> >
> > static int rcutorture_booster_cleanup(unsigned int cpu)
> > @@ -3686,6 +3868,10 @@ rcu_torture_cleanup(void)
> > nocb_tasks = NULL;
> > }
> >
> > + if (updown_task) {
> > + torture_stop_kthread(rcu_torture_updown, updown_task);
> > + updown_task = NULL;
> > + }
> > if (reader_tasks) {
> > for (i = 0; i < nrealreaders; i++)
> > torture_stop_kthread(rcu_torture_reader,
> > @@ -4216,6 +4402,9 @@ rcu_torture_init(void)
> > if (torture_init_error(firsterr))
> > goto unwind;
> > }
> > + firsterr = rcu_torture_updown_init();
> > + if (torture_init_error(firsterr))
> > + goto unwind;
> > nrealnocbers = nocbs_nthreads;
> > if (WARN_ON(nrealnocbers < 0))
> > nrealnocbers = 1;
> > --
> > 2.40.1
> >
> >
Paul,
>> If rtorsu_hrt timer is still in timer_queue, invoke hrtimer_cancel() will
>> remove it from timerqueue and directly return, so the rcu_torture_updown_hrt()
>> will not be executed and the rtorsup->rtorsu_inuse cannot be set false.
>>
>> How about modifying it as follows:
>>
>> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
>> index 04d7a2173b95..ecf3d3797f7e 100644
>> --- a/kernel/rcu/rcutorture.c
>> +++ b/kernel/rcu/rcutorture.c
>> @@ -2502,8 +2502,7 @@ static void rcu_torture_updown_cleanup(void)
>> for (rtorsup = updownreaders; rtorsup <
>> &updownreaders[n_up_down]; rtorsup++) {
>> if (!smp_load_acquire(&rtorsup->rtorsu_inuse))
>> continue;
>> - (void)hrtimer_cancel(&rtorsup->rtorsu_hrt);
>> - if (WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
>> + if (hrtimer_cancel(&rtorsup->rtorsu_hrt) ||
>> WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
>>
>> rcu_torture_one_read_end(&rtorsup->rtorsu_rtors, &rtorsup->rtorsu_trs,
>> -1);
>> WARN_ONCE(rtorsup->rtorsu_nups >=
>> rtorsup->rtorsu_ndowns, "%s: Up without matching down #%zu.\n",
>> __func__, rtorsup - updownreaders);
>> rtorsup->rtorsu_nups++;
>
> Good eyes, thank you! I have applied this fix with attribution.
Could you re-send the series, or should I apply the fix the patch myself? Or
provide the new patch inline here.
Thanks!
- Joel
On Thu, Mar 27, 2025 at 12:22:12PM -0400, Joel Fernandes wrote:
> Paul,
>
> >> If rtorsu_hrt timer is still in timer_queue, invoke hrtimer_cancel() will
> >> remove it from timerqueue and directly return, so the rcu_torture_updown_hrt()
> >> will not be executed and the rtorsup->rtorsu_inuse cannot be set false.
> >>
> >> How about modifying it as follows:
> >>
> >> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> >> index 04d7a2173b95..ecf3d3797f7e 100644
> >> --- a/kernel/rcu/rcutorture.c
> >> +++ b/kernel/rcu/rcutorture.c
> >> @@ -2502,8 +2502,7 @@ static void rcu_torture_updown_cleanup(void)
> >> for (rtorsup = updownreaders; rtorsup <
> >> &updownreaders[n_up_down]; rtorsup++) {
> >> if (!smp_load_acquire(&rtorsup->rtorsu_inuse))
> >> continue;
> >> - (void)hrtimer_cancel(&rtorsup->rtorsu_hrt);
> >> - if (WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
> >> + if (hrtimer_cancel(&rtorsup->rtorsu_hrt) ||
> >> WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
> >>
> >> rcu_torture_one_read_end(&rtorsup->rtorsu_rtors, &rtorsup->rtorsu_trs,
> >> -1);
> >> WARN_ONCE(rtorsup->rtorsu_nups >=
> >> rtorsup->rtorsu_ndowns, "%s: Up without matching down #%zu.\n",
> >> __func__, rtorsup - updownreaders);
> >> rtorsup->rtorsu_nups++;
> >
> > Good eyes, thank you! I have applied this fix with attribution.
>
> Could you re-send the series, or should I apply the fix the patch myself? Or
> provide the new patch inline here.
Your choice, just let me know. If you have modified any of the other
patches in that series, it will probably be easier for you if I either
resend just that one patch or if you apply the changes. If you haven't
done any modifications, it might be easier for you if I re-sent the
series.
I have the delta patch below, which I have pushed out for kernel test
robot ministrations and which I expect to merge into the original
later today.
Thanx, Paul
------------------------------------------------------------------------
commit 55fcac5cb3fc96479d935db648c98503cb0a944b
Author: Paul E. McKenney <paulmck@kernel.org>
Date: Thu Mar 27 07:29:48 2025 -0700
squash! rcutorture: Add tests for SRCU up/down reader primitives
[ paulmck: Apply Z qiang feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 04d7a2173b95d..ecf3d3797f7e1 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2502,8 +2502,7 @@ static void rcu_torture_updown_cleanup(void)
for (rtorsup = updownreaders; rtorsup < &updownreaders[n_up_down]; rtorsup++) {
if (!smp_load_acquire(&rtorsup->rtorsu_inuse))
continue;
- (void)hrtimer_cancel(&rtorsup->rtorsu_hrt);
- if (WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
+ if (hrtimer_cancel(&rtorsup->rtorsu_hrt) || WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
rcu_torture_one_read_end(&rtorsup->rtorsu_rtors, &rtorsup->rtorsu_trs, -1);
WARN_ONCE(rtorsup->rtorsu_nups >= rtorsup->rtorsu_ndowns, "%s: Up without matching down #%zu.\n", __func__, rtorsup - updownreaders);
rtorsup->rtorsu_nups++;
> On Mar 27, 2025, at 12:48 PM, Paul E. McKenney <paulmck@kernel.org> wrote:
>
> On Thu, Mar 27, 2025 at 12:22:12PM -0400, Joel Fernandes wrote:
>> Paul,
>>
>>>> If rtorsu_hrt timer is still in timer_queue, invoke hrtimer_cancel() will
>>>> remove it from timerqueue and directly return, so the rcu_torture_updown_hrt()
>>>> will not be executed and the rtorsup->rtorsu_inuse cannot be set false.
>>>>
>>>> How about modifying it as follows:
>>>>
>>>> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
>>>> index 04d7a2173b95..ecf3d3797f7e 100644
>>>> --- a/kernel/rcu/rcutorture.c
>>>> +++ b/kernel/rcu/rcutorture.c
>>>> @@ -2502,8 +2502,7 @@ static void rcu_torture_updown_cleanup(void)
>>>> for (rtorsup = updownreaders; rtorsup <
>>>> &updownreaders[n_up_down]; rtorsup++) {
>>>> if (!smp_load_acquire(&rtorsup->rtorsu_inuse))
>>>> continue;
>>>> - (void)hrtimer_cancel(&rtorsup->rtorsu_hrt);
>>>> - if (WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
>>>> + if (hrtimer_cancel(&rtorsup->rtorsu_hrt) ||
>>>> WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
>>>>
>>>> rcu_torture_one_read_end(&rtorsup->rtorsu_rtors, &rtorsup->rtorsu_trs,
>>>> -1);
>>>> WARN_ONCE(rtorsup->rtorsu_nups >=
>>>> rtorsup->rtorsu_ndowns, "%s: Up without matching down #%zu.\n",
>>>> __func__, rtorsup - updownreaders);
>>>> rtorsup->rtorsu_nups++;
>>>
>>> Good eyes, thank you! I have applied this fix with attribution.
>>
>> Could you re-send the series, or should I apply the fix the patch myself? Or
>> provide the new patch inline here.
>
> Your choice, just let me know. If you have modified any of the other
> patches in that series, it will probably be easier for you if I either
> resend just that one patch or if you apply the changes. If you haven't
> done any modifications, it might be easier for you if I re-sent the
> series.
Thanks, you could resend as I have not changed other patches.
- Joel
>
> I have the delta patch below, which I have pushed out for kernel test
> robot ministrations and which I expect to merge into the original
> later today.
>
> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> commit 55fcac5cb3fc96479d935db648c98503cb0a944b
> Author: Paul E. McKenney <paulmck@kernel.org>
> Date: Thu Mar 27 07:29:48 2025 -0700
>
> squash! rcutorture: Add tests for SRCU up/down reader primitives
>
> [ paulmck: Apply Z qiang feedback. ]
>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
>
> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> index 04d7a2173b95d..ecf3d3797f7e1 100644
> --- a/kernel/rcu/rcutorture.c
> +++ b/kernel/rcu/rcutorture.c
> @@ -2502,8 +2502,7 @@ static void rcu_torture_updown_cleanup(void)
> for (rtorsup = updownreaders; rtorsup < &updownreaders[n_up_down]; rtorsup++) {
> if (!smp_load_acquire(&rtorsup->rtorsu_inuse))
> continue;
> - (void)hrtimer_cancel(&rtorsup->rtorsu_hrt);
> - if (WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
> + if (hrtimer_cancel(&rtorsup->rtorsu_hrt) || WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
> rcu_torture_one_read_end(&rtorsup->rtorsu_rtors, &rtorsup->rtorsu_trs, -1);
> WARN_ONCE(rtorsup->rtorsu_nups >= rtorsup->rtorsu_ndowns, "%s: Up without matching down #%zu.\n", __func__, rtorsup - updownreaders);
> rtorsup->rtorsu_nups++;
On Thu, Mar 27, 2025 at 05:08:35PM +0000, Joel Fernandes wrote:
>
>
> > On Mar 27, 2025, at 12:48 PM, Paul E. McKenney <paulmck@kernel.org> wrote:
> >
> > On Thu, Mar 27, 2025 at 12:22:12PM -0400, Joel Fernandes wrote:
> >> Paul,
> >>
> >>>> If rtorsu_hrt timer is still in timer_queue, invoke hrtimer_cancel() will
> >>>> remove it from timerqueue and directly return, so the rcu_torture_updown_hrt()
> >>>> will not be executed and the rtorsup->rtorsu_inuse cannot be set false.
> >>>>
> >>>> How about modifying it as follows:
> >>>>
> >>>> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> >>>> index 04d7a2173b95..ecf3d3797f7e 100644
> >>>> --- a/kernel/rcu/rcutorture.c
> >>>> +++ b/kernel/rcu/rcutorture.c
> >>>> @@ -2502,8 +2502,7 @@ static void rcu_torture_updown_cleanup(void)
> >>>> for (rtorsup = updownreaders; rtorsup <
> >>>> &updownreaders[n_up_down]; rtorsup++) {
> >>>> if (!smp_load_acquire(&rtorsup->rtorsu_inuse))
> >>>> continue;
> >>>> - (void)hrtimer_cancel(&rtorsup->rtorsu_hrt);
> >>>> - if (WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
> >>>> + if (hrtimer_cancel(&rtorsup->rtorsu_hrt) ||
> >>>> WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
> >>>>
> >>>> rcu_torture_one_read_end(&rtorsup->rtorsu_rtors, &rtorsup->rtorsu_trs,
> >>>> -1);
> >>>> WARN_ONCE(rtorsup->rtorsu_nups >=
> >>>> rtorsup->rtorsu_ndowns, "%s: Up without matching down #%zu.\n",
> >>>> __func__, rtorsup - updownreaders);
> >>>> rtorsup->rtorsu_nups++;
> >>>
> >>> Good eyes, thank you! I have applied this fix with attribution.
> >>
> >> Could you re-send the series, or should I apply the fix the patch myself? Or
> >> provide the new patch inline here.
> >
> > Your choice, just let me know. If you have modified any of the other
> > patches in that series, it will probably be easier for you if I either
> > resend just that one patch or if you apply the changes. If you haven't
> > done any modifications, it might be easier for you if I re-sent the
> > series.
>
> Thanks, you could resend as I have not changed other patches.
Will do! I expect to get that to you by end of this coming Monday
at the latest.
Thanx, Paul
> - Joel
>
> >
> > I have the delta patch below, which I have pushed out for kernel test
> > robot ministrations and which I expect to merge into the original
> > later today.
> >
> > Thanx, Paul
> >
> > ------------------------------------------------------------------------
> >
> > commit 55fcac5cb3fc96479d935db648c98503cb0a944b
> > Author: Paul E. McKenney <paulmck@kernel.org>
> > Date: Thu Mar 27 07:29:48 2025 -0700
> >
> > squash! rcutorture: Add tests for SRCU up/down reader primitives
> >
> > [ paulmck: Apply Z qiang feedback. ]
> >
> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> >
> > diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> > index 04d7a2173b95d..ecf3d3797f7e1 100644
> > --- a/kernel/rcu/rcutorture.c
> > +++ b/kernel/rcu/rcutorture.c
> > @@ -2502,8 +2502,7 @@ static void rcu_torture_updown_cleanup(void)
> > for (rtorsup = updownreaders; rtorsup < &updownreaders[n_up_down]; rtorsup++) {
> > if (!smp_load_acquire(&rtorsup->rtorsu_inuse))
> > continue;
> > - (void)hrtimer_cancel(&rtorsup->rtorsu_hrt);
> > - if (WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
> > + if (hrtimer_cancel(&rtorsup->rtorsu_hrt) || WARN_ON_ONCE(rtorsup->rtorsu_inuse)) {
> > rcu_torture_one_read_end(&rtorsup->rtorsu_rtors, &rtorsup->rtorsu_trs, -1);
> > WARN_ONCE(rtorsup->rtorsu_nups >= rtorsup->rtorsu_ndowns, "%s: Up without matching down #%zu.\n", __func__, rtorsup - updownreaders);
> > rtorsup->rtorsu_nups++;
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