Add trace destination field (trace_dst) to the _ddebug structure.
The trace destination field is used to determine output of debug
logs when +T is set. Setting trace_dst value to 0 (default) enables
output to prdbg and devdbg trace events. Setting trace_dst value to
a value in range of [1..255] enables output to trace instance.
Signed-off-by: Łukasz Bartosik <lb@semihalf.com>
---
include/linux/dynamic_debug.h | 13 +++++++++++--
lib/dynamic_debug.c | 28 +++++++++++++++++++---------
2 files changed, 30 insertions(+), 11 deletions(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 684766289bfc..3084302876b4 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -60,9 +60,18 @@ struct _ddebug {
#else
#define _DPRINTK_FLAGS_DEFAULT 0
#endif
- struct {
+ struct dd_ctrl {
unsigned int flags:8;
- unsigned unused:24;
+ /*
+ * The trace destination field is used to determine output of debug
+ * logs when +T is set. Setting trace_dst value to 0 (default) enables
+ * output to prdbg and devdbg trace events. Setting trace_dst value to
+ * a value in range of [1..255] enables output to trace instance.
+ */
+#define TRACE_DST_BITS 8
+ unsigned int trace_dst:TRACE_DST_BITS;
+#define TRACE_DST_MAX ((1 << TRACE_DST_BITS) - 1)
+ unsigned unused:16;
} ctrl;
} __attribute__((aligned(8)));
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index ca87adf327df..3218ab078a76 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -80,14 +80,24 @@ module_param(verbose, int, 0644);
MODULE_PARM_DESC(verbose, " dynamic_debug/control processing "
"( 0 = off (default), 1 = module add/rm, 2 = >control summary, 3 = parsing, 4 = per-site changes)");
+static inline struct dd_ctrl *get_ctrl(struct _ddebug *desc)
+{
+ return &desc->ctrl;
+}
+
+static inline void set_ctrl(struct _ddebug *desc, struct dd_ctrl *ctrl)
+{
+ desc->ctrl = *ctrl;
+}
+
static inline unsigned int get_flags(const struct _ddebug *desc)
{
return desc->ctrl.flags;
}
-static inline void set_flags(struct _ddebug *desc, unsigned int val)
+static inline unsigned int get_trace_dst(const struct _ddebug *desc)
{
- desc->ctrl.flags = val;
+ return desc->ctrl.trace_dst;
}
/* Return the path relative to source root */
@@ -190,8 +200,8 @@ static int ddebug_change(const struct ddebug_query *query,
{
int i;
struct ddebug_table *dt;
- unsigned int newflags;
unsigned int nfound = 0;
+ struct dd_ctrl nctrl = {0};
struct flagsbuf fbuf, nbuf;
struct ddebug_class_map *map = NULL;
int __outvar valid_class;
@@ -257,14 +267,14 @@ static int ddebug_change(const struct ddebug_query *query,
nfound++;
- newflags = (get_flags(dp) & modifiers->mask) | modifiers->flags;
- if (newflags == get_flags(dp))
+ nctrl.flags = (get_flags(dp) & modifiers->mask) | modifiers->flags;
+ if (!memcmp(&nctrl, get_ctrl(dp), sizeof(struct dd_ctrl)))
continue;
#ifdef CONFIG_JUMP_LABEL
if (get_flags(dp) & _DPRINTK_FLAGS_ENABLED) {
- if (!(newflags & _DPRINTK_FLAGS_ENABLED))
+ if (!(nctrl.flags & _DPRINTK_FLAGS_ENABLED))
static_branch_disable(&dp->key.dd_key_true);
- } else if (newflags & _DPRINTK_FLAGS_ENABLED) {
+ } else if (nctrl.flags & _DPRINTK_FLAGS_ENABLED) {
static_branch_enable(&dp->key.dd_key_true);
}
#endif
@@ -272,8 +282,8 @@ static int ddebug_change(const struct ddebug_query *query,
trim_prefix(dp->filename), dp->lineno,
dt->mod_name, dp->function,
ddebug_describe_flags(get_flags(dp), &fbuf),
- ddebug_describe_flags(newflags, &nbuf));
- set_flags(dp, newflags);
+ ddebug_describe_flags(nctrl.flags, &nbuf));
+ set_ctrl(dp, &nctrl);
}
}
mutex_unlock(&ddebug_lock);
--
2.42.0.869.gea05f2083d-goog
On Fri, Nov 3, 2023 at 7:10 AM Łukasz Bartosik <lb@semihalf.com> wrote: > > Add trace destination field (trace_dst) to the _ddebug structure. > The trace destination field is used to determine output of debug > logs when +T is set. Setting trace_dst value to 0 (default) enables > output to prdbg and devdbg trace events. Setting trace_dst value to > a value in range of [1..255] enables output to trace instance. should we do some expectation setting here ? 255 is something of a promise to more than tom,dick,harry. 16-64 is more suggestive of a limited resource, might encourage more judicious use. will look further later
sob., 4 lis 2023 o 02:39 <jim.cromie@gmail.com> napisał(a): > > On Fri, Nov 3, 2023 at 7:10 AM Łukasz Bartosik <lb@semihalf.com> wrote: > > > > Add trace destination field (trace_dst) to the _ddebug structure. > > The trace destination field is used to determine output of debug > > logs when +T is set. Setting trace_dst value to 0 (default) enables > > output to prdbg and devdbg trace events. Setting trace_dst value to > > a value in range of [1..255] enables output to trace instance. > > > should we do some expectation setting here ? > 255 is something of a promise to more than tom,dick,harry. > 16-64 is more suggestive of a limited resource, > might encourage more judicious use. > How about making it configurable in kernel Kconfig with default value set to 16 or 32 ? > will look further later
On Fri, Nov 10, 2023 at 7:52 AM Łukasz Bartosik <lb@semihalf.com> wrote: > > sob., 4 lis 2023 o 02:39 <jim.cromie@gmail.com> napisał(a): > > > > On Fri, Nov 3, 2023 at 7:10 AM Łukasz Bartosik <lb@semihalf.com> wrote: > > > > > > Add trace destination field (trace_dst) to the _ddebug structure. > > > The trace destination field is used to determine output of debug > > > logs when +T is set. Setting trace_dst value to 0 (default) enables > > > output to prdbg and devdbg trace events. Setting trace_dst value to > > > a value in range of [1..255] enables output to trace instance. > > > > > > should we do some expectation setting here ? > > 255 is something of a promise to more than tom,dick,harry. > > 16-64 is more suggestive of a limited resource, > > might encourage more judicious use. > > > > How about making it configurable in kernel Kconfig with default value > set to 16 or 32 ? > given the general dislike of extra knobs, it's not the battle I would choose. ISTM we could start small, add bits later (if needed) maybe 16 is too parsimonious; esp if DRM wants multiple instances per driver (device?) > > will look further later
pt., 10 lis 2023 o 20:37 <jim.cromie@gmail.com> napisał(a): > > On Fri, Nov 10, 2023 at 7:52 AM Łukasz Bartosik <lb@semihalf.com> wrote: > > > > sob., 4 lis 2023 o 02:39 <jim.cromie@gmail.com> napisał(a): > > > > > > On Fri, Nov 3, 2023 at 7:10 AM Łukasz Bartosik <lb@semihalf.com> wrote: > > > > > > > > Add trace destination field (trace_dst) to the _ddebug structure. > > > > The trace destination field is used to determine output of debug > > > > logs when +T is set. Setting trace_dst value to 0 (default) enables > > > > output to prdbg and devdbg trace events. Setting trace_dst value to > > > > a value in range of [1..255] enables output to trace instance. > > > > > > > > > should we do some expectation setting here ? > > > 255 is something of a promise to more than tom,dick,harry. > > > 16-64 is more suggestive of a limited resource, > > > might encourage more judicious use. > > > > > > > How about making it configurable in kernel Kconfig with default value > > set to 16 or 32 ? > > > > given the general dislike of extra knobs, it's not the battle I would choose. > ISTM we could start small, add bits later (if needed) > maybe 16 is too parsimonious; esp if DRM wants multiple instances per > driver (device?) > If we don't want the extra config knob then I would opt for 64. > > > > > will look further later
On Sun, Nov 12, 2023 at 9:29 AM Łukasz Bartosik <lb@semihalf.com> wrote: > > pt., 10 lis 2023 o 20:37 <jim.cromie@gmail.com> napisał(a): > > > > On Fri, Nov 10, 2023 at 7:52 AM Łukasz Bartosik <lb@semihalf.com> wrote: > > > > > > sob., 4 lis 2023 o 02:39 <jim.cromie@gmail.com> napisał(a): > > > > > > > > On Fri, Nov 3, 2023 at 7:10 AM Łukasz Bartosik <lb@semihalf.com> wrote: > > > > > > > > > > Add trace destination field (trace_dst) to the _ddebug structure. > > > > > The trace destination field is used to determine output of debug > > > > > logs when +T is set. Setting trace_dst value to 0 (default) enables > > > > > output to prdbg and devdbg trace events. Setting trace_dst value to > > > > > a value in range of [1..255] enables output to trace instance. > > > > > > > > > > > > should we do some expectation setting here ? > > > > 255 is something of a promise to more than tom,dick,harry. > > > > 16-64 is more suggestive of a limited resource, > > > > might encourage more judicious use. > > > > > > > > > > How about making it configurable in kernel Kconfig with default value > > > set to 16 or 32 ? > > > > > > > given the general dislike of extra knobs, it's not the battle I would choose. > > ISTM we could start small, add bits later (if needed) > > maybe 16 is too parsimonious; esp if DRM wants multiple instances per > > driver (device?) > > > > If we don't want the extra config knob then I would opt for 64. I think I could live with that. And I dont foresee other uses for spare bits atm.
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