ratelimit: make output more useful
in [Kernel]
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From: Ingo Molnar on 23 Oct 2009 07:40 * Christian Borntraeger <borntraeger(a)de.ibm.com> wrote: > Today I got > > > [39648.224782] Registered led device: iwl-phy0::TX > [40676.545099] __ratelimit: 246 callbacks suppressed > [40676.545103] abcdef[23675]: segfault at 0 ... > > as you can see the ratelimit message contains a function prefix. Since this is > always __ratelimit, this wont help much. This patch changes __ratelimit and > printk_ratelimit to print the function name that calls ratelimit. > > Opinions? > > Signed-off-by: Christian Borntraeger <borntraeger(a)de.ibm.com> > > CC: Andrew Morton <akpm(a)linux-foundation.org> > CC: Ingo Molnar <mingo(a)elte.hu> > CC: Dave Young <hidave.darkstar(a)gmail.com> > > include/linux/kernel.h | 6 +++++- > include/linux/ratelimit.h | 3 ++- > kernel/printk.c | 9 +-------- > lib/ratelimit.c | 6 +++--- > 4 files changed, 11 insertions(+), 13 deletions(-) > > Index: linux-2.6/include/linux/kernel.h > =================================================================== > --- linux-2.6.orig/include/linux/kernel.h > +++ linux-2.6/include/linux/kernel.h > @@ -241,8 +241,12 @@ asmlinkage int vprintk(const char *fmt, > asmlinkage int printk(const char * fmt, ...) > __attribute__ ((format (printf, 1, 2))) __cold; > > +/* > + * printk rate limiting, lifted from the networking subsystem. > + */ > extern struct ratelimit_state printk_ratelimit_state; > -extern int printk_ratelimit(void); > +#define printk_ratelimit() ___ratelimit(&printk_ratelimit_state, __func__) > + > extern bool printk_timed_ratelimit(unsigned long *caller_jiffies, > unsigned int interval_msec); > > Index: linux-2.6/include/linux/ratelimit.h > =================================================================== > --- linux-2.6.orig/include/linux/ratelimit.h > +++ linux-2.6/include/linux/ratelimit.h > @@ -16,5 +16,6 @@ struct ratelimit_state { > #define DEFINE_RATELIMIT_STATE(name, interval, burst) \ > struct ratelimit_state name = {interval, burst,} > > -extern int __ratelimit(struct ratelimit_state *rs); > +extern int ___ratelimit(struct ratelimit_state *rs, const char *func); > +#define __ratelimit(state) ___ratelimit(state, __func__) > #endif > Index: linux-2.6/kernel/printk.c > =================================================================== > --- linux-2.6.orig/kernel/printk.c > +++ linux-2.6/kernel/printk.c > @@ -1369,18 +1369,11 @@ late_initcall(disable_boot_consoles); > #if defined CONFIG_PRINTK > > /* > - * printk rate limiting, lifted from the networking subsystem. > - * > * This enforces a rate limit: not more than 10 kernel messages > * every 5s to make a denial-of-service attack impossible. > */ > DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); > - > -int printk_ratelimit(void) > -{ > - return __ratelimit(&printk_ratelimit_state); > -} > -EXPORT_SYMBOL(printk_ratelimit); > +EXPORT_SYMBOL(printk_ratelimit_state); > > /** > * printk_timed_ratelimit - caller-controlled printk ratelimiting > Index: linux-2.6/lib/ratelimit.c > =================================================================== > --- linux-2.6.orig/lib/ratelimit.c > +++ linux-2.6/lib/ratelimit.c > @@ -23,7 +23,7 @@ static DEFINE_SPINLOCK(ratelimit_lock); > * This enforces a rate limit: not more than @rs->ratelimit_burst callbacks > * in every @rs->ratelimit_jiffies > */ > -int __ratelimit(struct ratelimit_state *rs) > +int ___ratelimit(struct ratelimit_state *rs, const char *func) > { > unsigned long flags; > > @@ -37,7 +37,7 @@ int __ratelimit(struct ratelimit_state * > if (time_is_before_jiffies(rs->begin + rs->interval)) { > if (rs->missed) > printk(KERN_WARNING "%s: %d callbacks suppressed\n", > - __func__, rs->missed); > + func, rs->missed); > rs->begin = 0; > rs->printed = 0; > rs->missed = 0; > @@ -54,4 +54,4 @@ print: > spin_unlock_irqrestore(&ratelimit_lock, flags); > return 1; > } > -EXPORT_SYMBOL(__ratelimit); > +EXPORT_SYMBOL(___ratelimit); Makes quite a bit of sense. Mind sending it against latest tip:master (or tip:core/printk): http://people.redhat.com/mingo/tip.git/README Which has a couple of ratelimit changes queued up already that collide with your patch: Hunk #1 FAILED at 241. 1 out of 1 hunk FAILED -- rejects in file include/linux/kernel.h patching file include/linux/ratelimit.h Hunk #1 FAILED at 16. 1 out of 1 hunk FAILED -- rejects in file include/linux/ratelimit.h patching file kernel/printk.c Hunk #1 succeeded at 1357 (offset -12 lines). patching file lib/ratelimit.c Hunk #1 succeeded at 20 with fuzz 1 (offset -3 lines). Hunk #2 FAILED at 34. Hunk #3 succeeded at 62 with fuzz 2 (offset 8 lines). 1 out of 3 hunks FAILED -- rejects in file lib/ratelimit.c Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Christian Borntraeger on 24 Oct 2009 13:00 Am Freitag 23 Oktober 2009 16:55:09 schrieb Ingo Molnar: > Any reason why it couldnt be pushed inside printk.c? We just need the > func string - not the pointer pass-in. That would also address some of > the call-site bloat. Right, I changed that and made the patch a bit simpler. So what about: [PATCH] ratelimit: make output more useful Today I got [39648.224782] Registered led device: iwl-phy0::TX [40676.545099] __ratelimit: 246 callbacks suppressed [40676.545103] abcdef[23675]: segfault at 0 ... as you can see the ratelimit message contains a function prefix. Since this is always __ratelimit, this wont help much. This patch changes __ratelimit and printk_ratelimit to print the function name that calls ratelimit. This will pinpoint the responsible function, as long as not several different places call ratelimit with the same ratelimit state at the same time. In that case we catch only one random function that calls ratelimit after the wait period. Signed-off-by: Christian Borntraeger <borntraeger(a)de.ibm.com> CC: Andrew Morton <akpm(a)linux-foundation.org> CC: Ingo Molnar <mingo(a)elte.hu> CC: Dave Young <hidave.darkstar(a)gmail.com> --- include/linux/kernel.h | 3 ++- include/linux/ratelimit.h | 3 ++- kernel/printk.c | 6 +++--- lib/ratelimit.c | 6 +++--- 4 files changed, 10 insertions(+), 8 deletions(-) Index: tip/include/linux/kernel.h =================================================================== --- tip.orig/include/linux/kernel.h +++ tip/include/linux/kernel.h @@ -332,7 +332,8 @@ asmlinkage int vprintk(const char *fmt, asmlinkage int printk(const char * fmt, ...) __attribute__ ((format (printf, 1, 2))) __cold; -extern int printk_ratelimit(void); +extern int __printk_ratelimit(const char *func); +#define printk_ratelimit() __printk_ratelimit(__func__) extern bool printk_timed_ratelimit(unsigned long *caller_jiffies, unsigned int interval_msec); Index: tip/include/linux/ratelimit.h =================================================================== --- tip.orig/include/linux/ratelimit.h +++ tip/include/linux/ratelimit.h @@ -25,6 +25,7 @@ struct ratelimit_state { .burst = burst_init, \ } -extern int __ratelimit(struct ratelimit_state *rs); +extern int ___ratelimit(struct ratelimit_state *rs, const char *func); +#define __ratelimit(state) ___ratelimit(state, __func__) #endif /* _LINUX_RATELIMIT_H */ Index: tip/kernel/printk.c =================================================================== --- tip.orig/kernel/printk.c +++ tip/kernel/printk.c @@ -1377,11 +1377,11 @@ late_initcall(disable_boot_consoles); */ DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); -int printk_ratelimit(void) +int __printk_ratelimit(const char *func) { - return __ratelimit(&printk_ratelimit_state); + return ___ratelimit(&printk_ratelimit_state, func); } -EXPORT_SYMBOL(printk_ratelimit); +EXPORT_SYMBOL(__printk_ratelimit); /** * printk_timed_ratelimit - caller-controlled printk ratelimiting Index: tip/lib/ratelimit.c =================================================================== --- tip.orig/lib/ratelimit.c +++ tip/lib/ratelimit.c @@ -20,7 +20,7 @@ * This enforces a rate limit: not more than @rs->ratelimit_burst callbacks * in every @rs->ratelimit_jiffies */ -int __ratelimit(struct ratelimit_state *rs) +int ___ratelimit(struct ratelimit_state *rs, const char *func) { unsigned long flags; int ret; @@ -43,7 +43,7 @@ int __ratelimit(struct ratelimit_state * if (time_is_before_jiffies(rs->begin + rs->interval)) { if (rs->missed) printk(KERN_WARNING "%s: %d callbacks suppressed\n", - __func__, rs->missed); + func, rs->missed); rs->begin = 0; rs->printed = 0; rs->missed = 0; @@ -59,4 +59,4 @@ int __ratelimit(struct ratelimit_state * return ret; } -EXPORT_SYMBOL(__ratelimit); +EXPORT_SYMBOL(___ratelimit); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Christian Borntraeger on 24 Oct 2009 13:20 Am Freitag 23 Oktober 2009 15:11:14 schrieb Ingo Molnar: > btw., an effect of this will be a small amount of extra bloat at every > callsite of printk_ratelimit(). There's 200 of them kernel-wide, so i > guess it's OK as all these codepaths are atypical slowpaths already. Well, this patch is definitely no high priority. Maybe you could keep it in tip for a while and see if somebody complains? Christian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Ingo Molnar on 24 Oct 2009 13:20 * Christian Borntraeger <borntraeger(a)de.ibm.com> wrote: > Index: tip/include/linux/kernel.h > =================================================================== > --- tip.orig/include/linux/kernel.h > +++ tip/include/linux/kernel.h > @@ -16,6 +16,7 @@ > #include <linux/log2.h> > #include <linux/typecheck.h> > #include <linux/dynamic_debug.h> > +#include <linux/ratelimit.h> > #include <asm/byteorder.h> > #include <asm/bug.h> > hm, this will cause circular dependencies - see: 3fff4c4: printk: Remove ratelimit.h from kernel.h Any reason why it couldnt be pushed inside printk.c? We just need the func string - not the pointer pass-in. That would also address some of the call-site bloat. Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Ingo Molnar on 24 Oct 2009 13:30 * Christian Borntraeger <borntraeger(a)de.ibm.com> wrote: > Am Freitag 23 Oktober 2009 13:33:48 schrieb Ingo Molnar: > > Mind sending it against latest tip:master (or tip:core/printk): > [...] > > Which has a couple of ratelimit changes queued up already that collide > > with your patch: > > Sure, something like the following? > > [PATCH] ratelimit: make output more useful > > Today I got > > [39648.224782] Registered led device: iwl-phy0::TX > [40676.545099] __ratelimit: 246 callbacks suppressed > [40676.545103] abcdef[23675]: segfault at 0 ... btw., an effect of this will be a small amount of extra bloat at every callsite of printk_ratelimit(). There's 200 of them kernel-wide, so i guess it's OK as all these codepaths are atypical slowpaths already. Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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