[PATCH -mm] __ratelimit rewrite

From: Dave Young
Date: Sun May 04 2008 - 03:10:29 EST

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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.

Here rewrite the __ratelimit function, and use a ratelimit_state as parameter.
Thanks for hints from andrew.

Signed-off-by: Dave Young <hidave.darkstar@xxxxxxxxx>

---
include/asm-generic/bug.h | 4 +--
include/linux/kernel.h | 9 +------
include/linux/net.h | 3 --
include/linux/ratelimit.h | 20 +++++++++++++++
include/linux/rcupreempt.h | 7 +++--
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, 70 insertions(+), 60 deletions(-)

diff -uprN linux/include/asm-generic/bug.h linux.new/include/asm-generic/bug.h
--- linux/include/asm-generic/bug.h 2008-04-30 17:32:54.000000000 +0800
+++ linux.new/include/asm-generic/bug.h 2008-05-04 13:46:38.000000000 +0800
@@ -76,8 +76,8 @@ extern void warn_on_slowpath(const char
unlikely(__ret_warn_once); \
})

-#define WARN_ON_SECS(condition, state, secs) \
- WARN_ON((condition) && __ratelimit(state))
+#define WARN_ON_RATELIMIT(condition, state) \
+ WARN_ON((condition) && __ratelimit(state));

#ifdef CONFIG_SMP
# define WARN_ON_SMP(x) WARN_ON(x)
diff -uprN linux/include/linux/kernel.h linux.new/include/linux/kernel.h
--- linux/include/linux/kernel.h 2008-04-30 17:33:59.000000000 +0800
+++ linux.new/include/linux/kernel.h 2008-04-30 17:33:52.000000000 +0800
@@ -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>

@@ -187,12 +188,8 @@ asmlinkage int printk(const char * fmt,
extern int log_buf_get_len(void);
extern int log_buf_read(int idx);
extern int log_buf_copy(char *dest, int idx, int len);
-
-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
@@ -206,8 +203,6 @@ static inline int log_buf_get_len(void)
static inline int log_buf_read(int idx) { return 0; }
static inline int log_buf_copy(char *dest, int idx, int len) { 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 -uprN linux/include/linux/net.h linux.new/include/linux/net.h
--- linux/include/linux/net.h 2008-04-30 17:35:36.000000000 +0800
+++ linux.new/include/linux/net.h 2008-04-30 17:35:45.000000000 +0800
@@ -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 -uprN linux/include/linux/ratelimit.h linux.new/include/linux/ratelimit.h
--- linux/include/linux/ratelimit.h 1970-01-01 07:00:00.000000000 +0700
+++ linux.new/include/linux/ratelimit.h 2008-05-04 14:33:50.000000000 +0800
@@ -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 -uprN linux/include/linux/rcupreempt.h linux.new/include/linux/rcupreempt.h
--- linux/include/linux/rcupreempt.h 2008-04-30 17:35:00.000000000 +0800
+++ linux.new/include/linux/rcupreempt.h 2008-05-04 13:48:35.000000000 +0800
@@ -115,16 +115,19 @@ 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_SECS(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1, 10);
+ 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);
__get_cpu_var(rcu_dyntick_sched).dynticks++;
smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
- WARN_ON_SECS(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1), 10);
+ WARN_ON_RATELIMIT(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1),
+ &rs);
}

#else /* CONFIG_NO_HZ */
diff -uprN linux/kernel/printk.c linux.new/kernel/printk.c
--- linux/kernel/printk.c 2008-04-30 17:36:20.000000000 +0800
+++ linux.new/kernel/printk.c 2008-05-04 14:01:35.000000000 +0800
@@ -1323,6 +1323,8 @@ 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.
*
@@ -1330,22 +1332,9 @@ 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 -uprN linux/kernel/sysctl.c linux.new/kernel/sysctl.c
--- linux/kernel/sysctl.c 2008-04-30 17:36:39.000000000 +0800
+++ linux.new/kernel/sysctl.c 2008-04-30 17:36:46.000000000 +0800
@@ -623,7 +623,7 @@ 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,
@@ -632,7 +632,7 @@ 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 -uprN linux/lib/ratelimit.c linux.new/lib/ratelimit.c
--- linux/lib/ratelimit.c 2008-04-30 17:37:31.000000000 +0800
+++ linux.new/lib/ratelimit.c 2008-05-04 14:46:20.000000000 +0800
@@ -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 -uprN linux/net/core/sysctl_net_core.c linux.new/net/core/sysctl_net_core.c
--- linux/net/core/sysctl_net_core.c 2008-04-30 17:38:59.000000000 +0800
+++ linux.new/net/core/sysctl_net_core.c 2008-04-30 17:38:46.000000000 +0800
@@ -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 -uprN linux/net/core/utils.c linux.new/net/core/utils.c
--- linux/net/core/utils.c 2008-04-30 17:38:29.000000000 +0800
+++ linux.new/net/core/utils.c 2008-05-04 14:02:09.000000000 +0800
@@ -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);

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Next message: Sam Ravnborg: "kconfig - a suggestion how to fix the select issue"
Previous message: Takashi Iwai: "Re: [Bisected Regression] snd-intel-hda no longer produces sound on Toshiba Satellite A100"
Next in thread: David Miller: "Re: [PATCH -mm] __ratelimit rewrite"
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