printk ratelimiting rewrite

All ratelimit user use same jiffies and burst params, so some messages
(callbacks) will be lost.

For example:
a call printk_ratelimit(5 * HZ, 1)
b call printk_ratelimit(5 * HZ, 1) before the 5*HZ timeout of a, then b will
will be supressed.

- rewrite __ratelimit, and use a ratelimit_state as parameter.  Thanks for
  hints from andrew.

- Add WARN_ON_RATELIMIT, update rcupreempt.h

- remove __printk_ratelimit

- use __ratelimit in net_ratelimit

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dave Young 2008-07-25 01:45:58 -07:00 committed by Linus Torvalds
parent 2711b793eb
commit 717115e1a5
10 changed files with 79 additions and 56 deletions

View File

@ -97,6 +97,9 @@ extern void warn_slowpath(const char *file, const int line,
unlikely(__ret_warn_once); \
})
#define WARN_ON_RATELIMIT(condition, state) \
WARN_ON((condition) && __ratelimit(state))
#ifdef CONFIG_SMP
# define WARN_ON_SMP(x) WARN_ON(x)
#else

View File

@ -15,6 +15,7 @@
#include <linux/bitops.h>
#include <linux/log2.h>
#include <linux/typecheck.h>
#include <linux/ratelimit.h>
#include <asm/byteorder.h>
#include <asm/bug.h>
@ -189,11 +190,8 @@ asmlinkage int vprintk(const char *fmt, va_list args)
asmlinkage int printk(const char * fmt, ...)
__attribute__ ((format (printf, 1, 2))) __cold;
extern int printk_ratelimit_jiffies;
extern int printk_ratelimit_burst;
extern struct ratelimit_state printk_ratelimit_state;
extern int printk_ratelimit(void);
extern int __ratelimit(int ratelimit_jiffies, int ratelimit_burst);
extern int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst);
extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
unsigned int interval_msec);
#else
@ -204,8 +202,6 @@ static inline int printk(const char *s, ...)
__attribute__ ((format (printf, 1, 2)));
static inline int __cold printk(const char *s, ...) { return 0; }
static inline int printk_ratelimit(void) { return 0; }
static inline int __printk_ratelimit(int ratelimit_jiffies, \
int ratelimit_burst) { return 0; }
static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies, \
unsigned int interval_msec) \
{ return false; }

View File

@ -351,8 +351,7 @@ static const struct proto_ops name##_ops = { \
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
extern int net_msg_cost;
extern int net_msg_burst;
extern struct ratelimit_state net_ratelimit_state;
#endif
#endif /* __KERNEL__ */

27
include/linux/ratelimit.h Normal file
View File

@ -0,0 +1,27 @@
#ifndef _LINUX_RATELIMIT_H
#define _LINUX_RATELIMIT_H
#include <linux/param.h>
#define DEFAULT_RATELIMIT_INTERVAL (5 * HZ)
#define DEFAULT_RATELIMIT_BURST 10
struct ratelimit_state {
int interval;
int burst;
int printed;
int missed;
unsigned long begin;
};
#define DEFINE_RATELIMIT_STATE(name, interval, burst) \
struct ratelimit_state name = {interval, burst,}
extern int __ratelimit(struct ratelimit_state *rs);
static inline int ratelimit(void)
{
static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
return __ratelimit(&rs);
}
#endif

View File

@ -115,16 +115,21 @@ DECLARE_PER_CPU(struct rcu_dyntick_sched, rcu_dyntick_sched);
static inline void rcu_enter_nohz(void)
{
static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1);
smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
__get_cpu_var(rcu_dyntick_sched).dynticks++;
WARN_ON(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1);
WARN_ON_RATELIMIT(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1, &rs);
}
static inline void rcu_exit_nohz(void)
{
static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1);
smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
__get_cpu_var(rcu_dyntick_sched).dynticks++;
WARN_ON(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1));
WARN_ON_RATELIMIT(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1),
&rs);
}
#else /* CONFIG_NO_HZ */

View File

@ -1308,6 +1308,8 @@ void tty_write_message(struct tty_struct *tty, char *msg)
}
#if defined CONFIG_PRINTK
DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
/*
* printk rate limiting, lifted from the networking subsystem.
*
@ -1315,22 +1317,9 @@ void tty_write_message(struct tty_struct *tty, char *msg)
* every printk_ratelimit_jiffies to make a denial-of-service
* attack impossible.
*/
int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst)
{
return __ratelimit(ratelimit_jiffies, ratelimit_burst);
}
EXPORT_SYMBOL(__printk_ratelimit);
/* minimum time in jiffies between messages */
int printk_ratelimit_jiffies = 5 * HZ;
/* number of messages we send before ratelimiting */
int printk_ratelimit_burst = 10;
int printk_ratelimit(void)
{
return __printk_ratelimit(printk_ratelimit_jiffies,
printk_ratelimit_burst);
return __ratelimit(&printk_ratelimit_state);
}
EXPORT_SYMBOL(printk_ratelimit);

View File

@ -624,7 +624,7 @@ static struct ctl_table kern_table[] = {
{
.ctl_name = KERN_PRINTK_RATELIMIT,
.procname = "printk_ratelimit",
.data = &printk_ratelimit_jiffies,
.data = &printk_ratelimit_state.interval,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_jiffies,
@ -633,7 +633,7 @@ static struct ctl_table kern_table[] = {
{
.ctl_name = KERN_PRINTK_RATELIMIT_BURST,
.procname = "printk_ratelimit_burst",
.data = &printk_ratelimit_burst,
.data = &printk_ratelimit_state.burst,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec,

View File

@ -3,6 +3,9 @@
*
* Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
*
* 2008-05-01 rewrite the function and use a ratelimit_state data struct as
* parameter. Now every user can use their own standalone ratelimit_state.
*
* This file is released under the GPLv2.
*
*/
@ -11,41 +14,43 @@
#include <linux/jiffies.h>
#include <linux/module.h>
static DEFINE_SPINLOCK(ratelimit_lock);
static unsigned long flags;
/*
* __ratelimit - rate limiting
* @ratelimit_jiffies: minimum time in jiffies between two callbacks
* @ratelimit_burst: number of callbacks we do before ratelimiting
* @rs: ratelimit_state data
*
* This enforces a rate limit: not more than @ratelimit_burst callbacks
* in every ratelimit_jiffies
* This enforces a rate limit: not more than @rs->ratelimit_burst callbacks
* in every @rs->ratelimit_jiffies
*/
int __ratelimit(int ratelimit_jiffies, int ratelimit_burst)
int __ratelimit(struct ratelimit_state *rs)
{
static DEFINE_SPINLOCK(ratelimit_lock);
static unsigned toks = 10 * 5 * HZ;
static unsigned long last_msg;
static int missed;
unsigned long flags;
unsigned long now = jiffies;
if (!rs->interval)
return 1;
spin_lock_irqsave(&ratelimit_lock, flags);
toks += now - last_msg;
last_msg = now;
if (toks > (ratelimit_burst * ratelimit_jiffies))
toks = ratelimit_burst * ratelimit_jiffies;
if (toks >= ratelimit_jiffies) {
int lost = missed;
if (!rs->begin)
rs->begin = jiffies;
missed = 0;
toks -= ratelimit_jiffies;
spin_unlock_irqrestore(&ratelimit_lock, flags);
if (lost)
printk(KERN_WARNING "%s: %d messages suppressed\n",
__func__, lost);
return 1;
if (time_is_before_jiffies(rs->begin + rs->interval)) {
if (rs->missed)
printk(KERN_WARNING "%s: %d callbacks suppressed\n",
__func__, rs->missed);
rs->begin = 0;
rs->printed = 0;
rs->missed = 0;
}
missed++;
if (rs->burst && rs->burst > rs->printed)
goto print;
rs->missed++;
spin_unlock_irqrestore(&ratelimit_lock, flags);
return 0;
print:
rs->printed++;
spin_unlock_irqrestore(&ratelimit_lock, flags);
return 1;
}
EXPORT_SYMBOL(__ratelimit);

View File

@ -67,7 +67,7 @@ static struct ctl_table net_core_table[] = {
{
.ctl_name = NET_CORE_MSG_COST,
.procname = "message_cost",
.data = &net_msg_cost,
.data = &net_ratelimit_state.interval,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_jiffies,
@ -76,7 +76,7 @@ static struct ctl_table net_core_table[] = {
{
.ctl_name = NET_CORE_MSG_BURST,
.procname = "message_burst",
.data = &net_msg_burst,
.data = &net_ratelimit_state.burst,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec,

View File

@ -31,17 +31,16 @@
#include <asm/system.h>
#include <asm/uaccess.h>
int net_msg_cost __read_mostly = 5*HZ;
int net_msg_burst __read_mostly = 10;
int net_msg_warn __read_mostly = 1;
EXPORT_SYMBOL(net_msg_warn);
DEFINE_RATELIMIT_STATE(net_ratelimit_state, 5 * HZ, 10);
/*
* All net warning printk()s should be guarded by this function.
*/
int net_ratelimit(void)
{
return __printk_ratelimit(net_msg_cost, net_msg_burst);
return __ratelimit(&net_ratelimit_state);
}
EXPORT_SYMBOL(net_ratelimit);