If someone stores both a timer and a workqueue in a hash map, on free, we
would walk it twice.
Add a check in htab_free_malloced_timers_or_wq and free the timers
and workqueues if they are present.
Fixes: 246331e3f1ea ("bpf: allow struct bpf_wq to be embedded in arraymaps and hashmaps")
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
---
kernel/bpf/hashtab.c | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 0179183c543a..20162ae741e9 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -1515,7 +1515,7 @@ static void delete_all_elements(struct bpf_htab *htab)
migrate_enable();
}
-static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer)
+static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab)
{
int i;
@@ -1527,10 +1527,10 @@ static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer
hlist_nulls_for_each_entry(l, n, head, hash_node) {
/* We only free timer on uref dropping to zero */
- if (is_timer)
+ if (btf_record_has_field(htab->map.record, BPF_TIMER))
bpf_obj_free_timer(htab->map.record,
l->key + round_up(htab->map.key_size, 8));
- else
+ if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE))
bpf_obj_free_workqueue(htab->map.record,
l->key + round_up(htab->map.key_size, 8));
}
@@ -1544,18 +1544,12 @@ static void htab_map_free_timers_and_wq(struct bpf_map *map)
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
/* We only free timer and workqueue on uref dropping to zero */
- if (btf_record_has_field(htab->map.record, BPF_TIMER)) {
+ if (btf_record_has_field(htab->map.record, BPF_TIMER | BPF_WORKQUEUE)) {
if (!htab_is_prealloc(htab))
- htab_free_malloced_timers_or_wq(htab, true);
+ htab_free_malloced_timers_or_wq(htab);
else
htab_free_prealloced_timers(htab);
}
- if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE)) {
- if (!htab_is_prealloc(htab))
- htab_free_malloced_timers_or_wq(htab, false);
- else
- htab_free_prealloced_wq(htab);
- }
}
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
--
2.44.0Hi Benjamin,
kernel test robot noticed the following build warnings:
[auto build test WARNING on 52578f7f53ff8fe3a8f6f3bc8b5956615c07a16e]
url: https://github.com/intel-lab-lkp/linux/commits/Benjamin-Tissoires/bpf-do-not-walk-twice-the-map-on-free/20240425-220322
base: 52578f7f53ff8fe3a8f6f3bc8b5956615c07a16e
patch link: https://lore.kernel.org/r/20240425-bpf-next-v1-2-1d8330e6c643%40kernel.org
patch subject: [PATCH 2/3] bpf: do not walk twice the hash map on free
config: arc-randconfig-002-20240426 (https://download.01.org/0day-ci/archive/20240426/202404260653.ULrCGrp2-lkp@intel.com/config)
compiler: arc-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240426/202404260653.ULrCGrp2-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404260653.ULrCGrp2-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> kernel/bpf/hashtab.c:243:13: warning: 'htab_free_prealloced_wq' defined but not used [-Wunused-function]
243 | static void htab_free_prealloced_wq(struct bpf_htab *htab)
| ^~~~~~~~~~~~~~~~~~~~~~~
vim +/htab_free_prealloced_wq +243 kernel/bpf/hashtab.c
68134668c17f31 Alexei Starovoitov 2021-07-14 242
246331e3f1eac9 Benjamin Tissoires 2024-04-20 @243 static void htab_free_prealloced_wq(struct bpf_htab *htab)
246331e3f1eac9 Benjamin Tissoires 2024-04-20 244 {
246331e3f1eac9 Benjamin Tissoires 2024-04-20 245 u32 num_entries = htab->map.max_entries;
246331e3f1eac9 Benjamin Tissoires 2024-04-20 246 int i;
246331e3f1eac9 Benjamin Tissoires 2024-04-20 247
246331e3f1eac9 Benjamin Tissoires 2024-04-20 248 if (!btf_record_has_field(htab->map.record, BPF_WORKQUEUE))
246331e3f1eac9 Benjamin Tissoires 2024-04-20 249 return;
246331e3f1eac9 Benjamin Tissoires 2024-04-20 250 if (htab_has_extra_elems(htab))
246331e3f1eac9 Benjamin Tissoires 2024-04-20 251 num_entries += num_possible_cpus();
246331e3f1eac9 Benjamin Tissoires 2024-04-20 252
246331e3f1eac9 Benjamin Tissoires 2024-04-20 253 for (i = 0; i < num_entries; i++) {
246331e3f1eac9 Benjamin Tissoires 2024-04-20 254 struct htab_elem *elem;
246331e3f1eac9 Benjamin Tissoires 2024-04-20 255
246331e3f1eac9 Benjamin Tissoires 2024-04-20 256 elem = get_htab_elem(htab, i);
246331e3f1eac9 Benjamin Tissoires 2024-04-20 257 bpf_obj_free_workqueue(htab->map.record,
246331e3f1eac9 Benjamin Tissoires 2024-04-20 258 elem->key + round_up(htab->map.key_size, 8));
246331e3f1eac9 Benjamin Tissoires 2024-04-20 259 cond_resched();
246331e3f1eac9 Benjamin Tissoires 2024-04-20 260 }
246331e3f1eac9 Benjamin Tissoires 2024-04-20 261 }
246331e3f1eac9 Benjamin Tissoires 2024-04-20 262
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
On Thu, Apr 25, 2024 at 6:59 AM Benjamin Tissoires <bentiss@kernel.org> wrote:
>
> If someone stores both a timer and a workqueue in a hash map, on free, we
> would walk it twice.
> Add a check in htab_free_malloced_timers_or_wq and free the timers
> and workqueues if they are present.
>
> Fixes: 246331e3f1ea ("bpf: allow struct bpf_wq to be embedded in arraymaps and hashmaps")
> Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
> ---
> kernel/bpf/hashtab.c | 16 +++++-----------
> 1 file changed, 5 insertions(+), 11 deletions(-)
>
> diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
> index 0179183c543a..20162ae741e9 100644
> --- a/kernel/bpf/hashtab.c
> +++ b/kernel/bpf/hashtab.c
> @@ -1515,7 +1515,7 @@ static void delete_all_elements(struct bpf_htab *htab)
> migrate_enable();
> }
>
> -static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer)
> +static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab)
> {
> int i;
>
> @@ -1527,10 +1527,10 @@ static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer
>
> hlist_nulls_for_each_entry(l, n, head, hash_node) {
> /* We only free timer on uref dropping to zero */
> - if (is_timer)
> + if (btf_record_has_field(htab->map.record, BPF_TIMER))
> bpf_obj_free_timer(htab->map.record,
> l->key + round_up(htab->map.key_size, 8));
> - else
> + if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE))
> bpf_obj_free_workqueue(htab->map.record,
> l->key + round_up(htab->map.key_size, 8));
> }
> @@ -1544,18 +1544,12 @@ static void htab_map_free_timers_and_wq(struct bpf_map *map)
> struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
>
> /* We only free timer and workqueue on uref dropping to zero */
> - if (btf_record_has_field(htab->map.record, BPF_TIMER)) {
> + if (btf_record_has_field(htab->map.record, BPF_TIMER | BPF_WORKQUEUE)) {
> if (!htab_is_prealloc(htab))
> - htab_free_malloced_timers_or_wq(htab, true);
> + htab_free_malloced_timers_or_wq(htab);
> else
> htab_free_prealloced_timers(htab);
> }
> - if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE)) {
> - if (!htab_is_prealloc(htab))
> - htab_free_malloced_timers_or_wq(htab, false);
> - else
> - htab_free_prealloced_wq(htab);
This looks wrong.
htab_free_prealloced_wq() is now unused as compiler says:
../kernel/bpf/hashtab.c:243:13: warning: ‘htab_free_prealloced_wq’
defined but not used [-Wunused-function]
243 | static void htab_free_prealloced_wq(struct bpf_htab *htab)
| ^~~~~~~~~~~~~~~~~~~~~~~
and prealloced maps with wq leak wq-s.
pw-bot: cr
On Apr 25 2024, Alexei Starovoitov wrote:
> On Thu, Apr 25, 2024 at 6:59 AM Benjamin Tissoires <bentiss@kernel.org> wrote:
> >
> > If someone stores both a timer and a workqueue in a hash map, on free, we
> > would walk it twice.
> > Add a check in htab_free_malloced_timers_or_wq and free the timers
> > and workqueues if they are present.
> >
> > Fixes: 246331e3f1ea ("bpf: allow struct bpf_wq to be embedded in arraymaps and hashmaps")
> > Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
> > ---
> > kernel/bpf/hashtab.c | 16 +++++-----------
> > 1 file changed, 5 insertions(+), 11 deletions(-)
> >
> > diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
> > index 0179183c543a..20162ae741e9 100644
> > --- a/kernel/bpf/hashtab.c
> > +++ b/kernel/bpf/hashtab.c
> > @@ -1515,7 +1515,7 @@ static void delete_all_elements(struct bpf_htab *htab)
> > migrate_enable();
> > }
> >
> > -static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer)
> > +static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab)
> > {
> > int i;
> >
> > @@ -1527,10 +1527,10 @@ static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer
> >
> > hlist_nulls_for_each_entry(l, n, head, hash_node) {
> > /* We only free timer on uref dropping to zero */
> > - if (is_timer)
> > + if (btf_record_has_field(htab->map.record, BPF_TIMER))
> > bpf_obj_free_timer(htab->map.record,
> > l->key + round_up(htab->map.key_size, 8));
> > - else
> > + if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE))
> > bpf_obj_free_workqueue(htab->map.record,
> > l->key + round_up(htab->map.key_size, 8));
> > }
> > @@ -1544,18 +1544,12 @@ static void htab_map_free_timers_and_wq(struct bpf_map *map)
> > struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
> >
> > /* We only free timer and workqueue on uref dropping to zero */
> > - if (btf_record_has_field(htab->map.record, BPF_TIMER)) {
> > + if (btf_record_has_field(htab->map.record, BPF_TIMER | BPF_WORKQUEUE)) {
> > if (!htab_is_prealloc(htab))
> > - htab_free_malloced_timers_or_wq(htab, true);
> > + htab_free_malloced_timers_or_wq(htab);
> > else
> > htab_free_prealloced_timers(htab);
> > }
> > - if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE)) {
> > - if (!htab_is_prealloc(htab))
> > - htab_free_malloced_timers_or_wq(htab, false);
> > - else
> > - htab_free_prealloced_wq(htab);
>
> This looks wrong.
> htab_free_prealloced_wq() is now unused as compiler says:
> ../kernel/bpf/hashtab.c:243:13: warning: ‘htab_free_prealloced_wq’
> defined but not used [-Wunused-function]
> 243 | static void htab_free_prealloced_wq(struct bpf_htab *htab)
> | ^~~~~~~~~~~~~~~~~~~~~~~
>
> and prealloced maps with wq leak wq-s.
oops, you are right. Sending a v2 right away (sorry for the delay).
Cheers,
Benjamin
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