From 6b1d174b0c27b5de421eda55c2731f32b6bd9852 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Tue, 2 Aug 2016 14:04:04 -0700 Subject: [PATCH] ratelimit: extend to print suppressed messages on release MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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@alien8.de Signed-off-by: Borislav Petkov Cc: Dave Young Cc: Franck Bui Cc: Greg Kroah-Hartman Cc: Ingo Molnar Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Uwe Kleine-König Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/ratelimit.h | 38 +++++++++++++++++++++++++++++++++----- lib/ratelimit.c | 10 ++++++---- 2 files changed, 39 insertions(+), 9 deletions(-) diff --git a/include/linux/ratelimit.h b/include/linux/ratelimit.h index 18102529254eeb..57c9e0622a38db 100644 --- a/include/linux/ratelimit.h +++ b/include/linux/ratelimit.h @@ -2,11 +2,15 @@ #define _LINUX_RATELIMIT_H #include +#include #include #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 --git a/lib/ratelimit.c b/lib/ratelimit.c index 2c5de86460c5bb..08f8043cac619d 100644 --- a/lib/ratelimit.c +++ b/lib/ratelimit.c @@ -46,12 +46,14 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func) 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++;