From: Borislav Petkov <bp@xxxxxxx> Subject: ratelimit: extend to print suppressed messages on release Extend the ratelimiting facility to print the amount of suppressed lines when it is being released. This use case is aimed at short-termed, burst-like users for which we want to output the suppressed lines stats only once, after it has been disposed of. For an example, see /dev/kmsg usage in a follow-on patch. Also, change the printk() line we issue on release to not use "callbacks" as it is misleading: we're not suppressing callbacks but printk() calls. This has been separated from a previous patch by Linus. Link: http://lkml.kernel.org/r/20160716061745.15795-2-bp@xxxxxxxxx Signed-off-by: Borislav Petkov <bp@xxxxxxx> Cc: Dave Young <dyoung@xxxxxxxxxx> Cc: Franck Bui <fbui@xxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/ratelimit.h | 38 +++++++++++++++++++++++++++++++----- lib/ratelimit.c | 10 +++++---- 2 files changed, 39 insertions(+), 9 deletions(-) diff -puN include/linux/ratelimit.h~ratelimit-extend-to-print-suppressed-messages-on-release include/linux/ratelimit.h --- a/include/linux/ratelimit.h~ratelimit-extend-to-print-suppressed-messages-on-release +++ a/include/linux/ratelimit.h @@ -2,11 +2,15 @@ #define _LINUX_RATELIMIT_H #include <linux/param.h> +#include <linux/sched.h> #include <linux/spinlock.h> #define DEFAULT_RATELIMIT_INTERVAL (5 * HZ) #define DEFAULT_RATELIMIT_BURST 10 +/* issue num suppressed message on exit */ +#define RATELIMIT_MSG_ON_RELEASE BIT(0) + struct ratelimit_state { raw_spinlock_t lock; /* protect the state */ @@ -15,6 +19,7 @@ struct ratelimit_state { int printed; int missed; unsigned long begin; + unsigned long flags; }; #define RATELIMIT_STATE_INIT(name, interval_init, burst_init) { \ @@ -34,12 +39,35 @@ struct ratelimit_state { static inline void ratelimit_state_init(struct ratelimit_state *rs, int interval, int burst) { + memset(rs, 0, sizeof(*rs)); + raw_spin_lock_init(&rs->lock); - rs->interval = interval; - rs->burst = burst; - rs->printed = 0; - rs->missed = 0; - rs->begin = 0; + rs->interval = interval; + rs->burst = burst; +} + +static inline void ratelimit_default_init(struct ratelimit_state *rs) +{ + return ratelimit_state_init(rs, DEFAULT_RATELIMIT_INTERVAL, + DEFAULT_RATELIMIT_BURST); +} + +static inline void ratelimit_state_exit(struct ratelimit_state *rs) +{ + if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) + return; + + if (rs->missed) { + pr_warn("%s: %d output lines suppressed due to ratelimiting\n", + current->comm, rs->missed); + rs->missed = 0; + } +} + +static inline void +ratelimit_set_flags(struct ratelimit_state *rs, unsigned long flags) +{ + rs->flags = flags; } extern struct ratelimit_state printk_ratelimit_state; diff -puN lib/ratelimit.c~ratelimit-extend-to-print-suppressed-messages-on-release lib/ratelimit.c --- a/lib/ratelimit.c~ratelimit-extend-to-print-suppressed-messages-on-release +++ a/lib/ratelimit.c @@ -46,12 +46,14 @@ int ___ratelimit(struct ratelimit_state rs->begin = jiffies; if (time_is_before_jiffies(rs->begin + rs->interval)) { - if (rs->missed) - printk(KERN_WARNING "%s: %d callbacks suppressed\n", - func, rs->missed); + if (rs->missed) { + if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) { + pr_warn("%s: %d callbacks suppressed\n", func, rs->missed); + rs->missed = 0; + } + } rs->begin = jiffies; rs->printed = 0; - rs->missed = 0; } if (rs->burst && rs->burst > rs->printed) { rs->printed++; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
