The patch titled
printk ratelimiting rewrite
has been added to the -mm tree. Its filename is
printk-ratelimiting-rewrite.patch
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out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: printk ratelimiting rewrite
From: Dave Young <hidave.darkstar@xxxxxxxxx>
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@xxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/asm-generic/bug.h | 3 +
include/linux/kernel.h | 8 +---
include/linux/net.h | 3 -
include/linux/ratelimit.h | 20 ++++++++++++
include/linux/rcupreempt.h | 9 ++++-
kernel/printk.c | 17 +---------
kernel/sysctl.c | 4 +-
lib/ratelimit.c | 57 +++++++++++++++++++----------------
net/core/sysctl_net_core.c | 4 +-
net/core/utils.c | 5 +--
10 files changed, 73 insertions(+), 57 deletions(-)
diff -puN include/asm-generic/bug.h~printk-ratelimiting-rewrite include/asm-generic/bug.h
--- a/include/asm-generic/bug.h~printk-ratelimiting-rewrite
+++ a/include/asm-generic/bug.h
@@ -75,6 +75,9 @@ extern void warn_on_slowpath(const char
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
diff -puN include/linux/kernel.h~printk-ratelimiting-rewrite include/linux/kernel.h
--- a/include/linux/kernel.h~printk-ratelimiting-rewrite
+++ a/include/linux/kernel.h
@@ -14,6 +14,7 @@
#include <linux/compiler.h>
#include <linux/bitops.h>
#include <linux/log2.h>
+#include <linux/ratelimit.h>
#include <asm/byteorder.h>
#include <asm/bug.h>
@@ -185,11 +186,8 @@ asmlinkage int vprintk(const char *fmt,
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
@@ -200,8 +198,6 @@ 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; }
diff -puN include/linux/net.h~printk-ratelimiting-rewrite include/linux/net.h
--- a/include/linux/net.h~printk-ratelimiting-rewrite
+++ a/include/linux/net.h
@@ -338,8 +338,7 @@ 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__ */
diff -puN /dev/null include/linux/ratelimit.h
--- /dev/null
+++ a/include/linux/ratelimit.h
@@ -0,0 +1,20 @@
+#ifndef _LINUX_RATELIMIT_H
+#define _LINUX_RATELIMIT_H
+
+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 struct ratelimit_state rs;
+ return __ratelimit(&rs);
+}
+#endif
diff -puN include/linux/rcupreempt.h~printk-ratelimiting-rewrite include/linux/rcupreempt.h
--- a/include/linux/rcupreempt.h~printk-ratelimiting-rewrite
+++ a/include/linux/rcupreempt.h
@@ -115,16 +115,21 @@ DECLARE_PER_CPU(struct 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 */
diff -puN kernel/printk.c~printk-ratelimiting-rewrite kernel/printk.c
--- a/kernel/printk.c~printk-ratelimiting-rewrite
+++ a/kernel/printk.c
@@ -1330,6 +1330,8 @@ void tty_write_message(struct tty_struct
}
#if defined CONFIG_PRINTK
+
+DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
/*
* printk rate limiting, lifted from the networking subsystem.
*
@@ -1337,22 +1339,9 @@ void tty_write_message(struct tty_struct
* 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);
diff -puN kernel/sysctl.c~printk-ratelimiting-rewrite kernel/sysctl.c
--- a/kernel/sysctl.c~printk-ratelimiting-rewrite
+++ a/kernel/sysctl.c
@@ -613,7 +613,7 @@ 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,
@@ -622,7 +622,7 @@ 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,
diff -puN lib/ratelimit.c~printk-ratelimiting-rewrite lib/ratelimit.c
--- a/lib/ratelimit.c~printk-ratelimiting-rewrite
+++ a/lib/ratelimit.c
@@ -3,6 +3,9 @@
*
* Isolated from kernel/printk.c by Dave Young <hidave.darkstar@xxxxxxxxx>
*
+ * 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;
-
- 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 (!rs->begin)
+ 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);
+ 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);
diff -puN net/core/sysctl_net_core.c~printk-ratelimiting-rewrite net/core/sysctl_net_core.c
--- a/net/core/sysctl_net_core.c~printk-ratelimiting-rewrite
+++ a/net/core/sysctl_net_core.c
@@ -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,
diff -puN net/core/utils.c~printk-ratelimiting-rewrite net/core/utils.c
--- a/net/core/utils.c~printk-ratelimiting-rewrite
+++ a/net/core/utils.c
@@ -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);
_
Patches currently in -mm which might be from hidave.darkstar@xxxxxxxxx are
add-time_is_after_jiffies-and-others-which-compare-with-jiffies.patch
printk-ratelimiting-rewrite.patch
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