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>

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>
Dave Young · Linus Torvalds
1 parent 2711b793eb
Showing 10 changed files with 79 additions and 56 deletions Side-by-side Diff
include/asm-generic/bug.h
include/linux/kernel.h
include/linux/net.h
include/linux/ratelimit.h
include/linux/rcupreempt.h
kernel/printk.c
kernel/sysctl.c
lib/ratelimit.c
net/core/sysctl_net_core.c
net/core/utils.c
@@ -97,6 +97,9 @@
 	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
@@ -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 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 @@
 	__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; }
@@ -351,8 +351,7 @@
  
 #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__ */
+#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
@@ -115,16 +115,21 @@
  
 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 */
@@ -1308,6 +1308,8 @@
 }
  
 #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 @@
  * 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);
  
@@ -624,7 +624,7 @@
 	{
 		.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 @@
 	{
 		.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,
@@ -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.
  *
  */
  
  
  
  
  
  
  
  
@@ -11,42 +14,44 @@
 #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);
@@ -67,7 +67,7 @@
 	{
 		.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 @@
 	{
 		.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,
@@ -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);
...	...	@@ -97,6 +97,9 @@
97	97	unlikely(__ret_warn_once); \
98	98	})
99	99
	100	+#define WARN_ON_RATELIMIT(condition, state) \
	101	+ WARN_ON((condition) && __ratelimit(state))
	102	+
100	103	#ifdef CONFIG_SMP
101	104	# define WARN_ON_SMP(x) WARN_ON(x)
102	105	#else
...	...	@@ -15,6 +15,7 @@
15	15	#include <linux/bitops.h>
16	16	#include <linux/log2.h>
17	17	#include <linux/typecheck.h>
	18	+#include <linux/ratelimit.h>
18	19	#include <asm/byteorder.h>
19	20	#include <asm/bug.h>
20	21
21	22
...	...	@@ -189,11 +190,8 @@
189	190	asmlinkage int printk(const char * fmt, ...)
190	191	__attribute__ ((format (printf, 1, 2))) __cold;
191	192
192		-extern int printk_ratelimit_jiffies;
193		-extern int printk_ratelimit_burst;
	193	+extern struct ratelimit_state printk_ratelimit_state;
194	194	extern int printk_ratelimit(void);
195		-extern int __ratelimit(int ratelimit_jiffies, int ratelimit_burst);
196		-extern int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst);
197	195	extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
198	196	unsigned int interval_msec);
199	197	#else
...	...	@@ -204,8 +202,6 @@
204	202	__attribute__ ((format (printf, 1, 2)));
205	203	static inline int __cold printk(const char *s, ...) { return 0; }
206	204	static inline int printk_ratelimit(void) { return 0; }
207		-static inline int __printk_ratelimit(int ratelimit_jiffies, \
208		- int ratelimit_burst) { return 0; }
209	205	static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies, \
210	206	unsigned int interval_msec) \
211	207	{ return false; }
...	...	@@ -351,8 +351,7 @@
351	351
352	352	#ifdef CONFIG_SYSCTL
353	353	#include <linux/sysctl.h>
354		-extern int net_msg_cost;
355		-extern int net_msg_burst;
	354	+extern struct ratelimit_state net_ratelimit_state;
356	355	#endif
357	356
358	357	#endif /* __KERNEL__ */
	1	+#ifndef _LINUX_RATELIMIT_H
	2	+#define _LINUX_RATELIMIT_H
	3	+#include <linux/param.h>
	4	+
	5	+#define DEFAULT_RATELIMIT_INTERVAL (5 * HZ)
	6	+#define DEFAULT_RATELIMIT_BURST 10
	7	+
	8	+struct ratelimit_state {
	9	+ int interval;
	10	+ int burst;
	11	+ int printed;
	12	+ int missed;
	13	+ unsigned long begin;
	14	+};
	15	+
	16	+#define DEFINE_RATELIMIT_STATE(name, interval, burst) \
	17	+ struct ratelimit_state name = {interval, burst,}
	18	+
	19	+extern int __ratelimit(struct ratelimit_state *rs);
	20	+
	21	+static inline int ratelimit(void)
	22	+{
	23	+ static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
	24	+ DEFAULT_RATELIMIT_BURST);
	25	+ return __ratelimit(&rs);
	26	+}
	27	+#endif
...	...	@@ -115,16 +115,21 @@
115	115
116	116	static inline void rcu_enter_nohz(void)
117	117	{
	118	+ static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1);
	119	+
118	120	smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
119	121	__get_cpu_var(rcu_dyntick_sched).dynticks++;
120		- WARN_ON(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1);
	122	+ WARN_ON_RATELIMIT(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1, &rs);
121	123	}
122	124
123	125	static inline void rcu_exit_nohz(void)
124	126	{
	127	+ static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1);
	128	+
125	129	smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
126	130	__get_cpu_var(rcu_dyntick_sched).dynticks++;
127		- WARN_ON(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1));
	131	+ WARN_ON_RATELIMIT(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1),
	132	+ &rs);
128	133	}
129	134
130	135	#else /* CONFIG_NO_HZ */
...	...	@@ -1308,6 +1308,8 @@
1308	1308	}
1309	1309
1310	1310	#if defined CONFIG_PRINTK
	1311	+
	1312	+DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
1311	1313	/*
1312	1314	* printk rate limiting, lifted from the networking subsystem.
1313	1315	*
1314	1316
...	...	@@ -1315,22 +1317,9 @@
1315	1317	* every printk_ratelimit_jiffies to make a denial-of-service
1316	1318	* attack impossible.
1317	1319	*/
1318		-int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst)
1319		-{
1320		- return __ratelimit(ratelimit_jiffies, ratelimit_burst);
1321		-}
1322		-EXPORT_SYMBOL(__printk_ratelimit);
1323		-
1324		-/* minimum time in jiffies between messages */
1325		-int printk_ratelimit_jiffies = 5 * HZ;
1326		-
1327		-/* number of messages we send before ratelimiting */
1328		-int printk_ratelimit_burst = 10;
1329		-
1330	1320	int printk_ratelimit(void)
1331	1321	{
1332		- return __printk_ratelimit(printk_ratelimit_jiffies,
1333		- printk_ratelimit_burst);
	1322	+ return __ratelimit(&printk_ratelimit_state);
1334	1323	}
1335	1324	EXPORT_SYMBOL(printk_ratelimit);
1336	1325
...	...	@@ -624,7 +624,7 @@
624	624	{
625	625	.ctl_name = KERN_PRINTK_RATELIMIT,
626	626	.procname = "printk_ratelimit",
627		- .data = &printk_ratelimit_jiffies,
	627	+ .data = &printk_ratelimit_state.interval,
628	628	.maxlen = sizeof(int),
629	629	.mode = 0644,
630	630	.proc_handler = &proc_dointvec_jiffies,
...	...	@@ -633,7 +633,7 @@
633	633	{
634	634	.ctl_name = KERN_PRINTK_RATELIMIT_BURST,
635	635	.procname = "printk_ratelimit_burst",
636		- .data = &printk_ratelimit_burst,
	636	+ .data = &printk_ratelimit_state.burst,
637	637	.maxlen = sizeof(int),
638	638	.mode = 0644,
639	639	.proc_handler = &proc_dointvec,
...	...	@@ -3,6 +3,9 @@
3	3	*
4	4	* Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
5	5	*
	6	+ * 2008-05-01 rewrite the function and use a ratelimit_state data struct as
	7	+ * parameter. Now every user can use their own standalone ratelimit_state.
	8	+ *
6	9	* This file is released under the GPLv2.
7	10	*
8	11	*/
9	12
10	13
11	14
12	15
13	16
14	17
15	18
16	19
...	...	@@ -11,42 +14,44 @@
11	14	#include <linux/jiffies.h>
12	15	#include <linux/module.h>
13	16
	17	+static DEFINE_SPINLOCK(ratelimit_lock);
	18	+static unsigned long flags;
	19	+
14	20	/*
15	21	* __ratelimit - rate limiting
16		- * @ratelimit_jiffies: minimum time in jiffies between two callbacks
17		- * @ratelimit_burst: number of callbacks we do before ratelimiting
	22	+ * @rs: ratelimit_state data
18	23	*
19		- * This enforces a rate limit: not more than @ratelimit_burst callbacks
20		- * in every ratelimit_jiffies
	24	+ * This enforces a rate limit: not more than @rs->ratelimit_burst callbacks
	25	+ * in every @rs->ratelimit_jiffies
21	26	*/
22		-int __ratelimit(int ratelimit_jiffies, int ratelimit_burst)
	27	+int __ratelimit(struct ratelimit_state *rs)
23	28	{
24		- static DEFINE_SPINLOCK(ratelimit_lock);
25		- static unsigned toks = 10 * 5 * HZ;
26		- static unsigned long last_msg;
27		- static int missed;
28		- unsigned long flags;
29		- unsigned long now = jiffies;
	29	+ if (!rs->interval)
	30	+ return 1;
30	31
31	32	spin_lock_irqsave(&ratelimit_lock, flags);
32		- toks += now - last_msg;
33		- last_msg = now;
34		- if (toks > (ratelimit_burst * ratelimit_jiffies))
35		- toks = ratelimit_burst * ratelimit_jiffies;
36		- if (toks >= ratelimit_jiffies) {
37		- int lost = missed;
	33	+ if (!rs->begin)
	34	+ rs->begin = jiffies;
38	35
39		- missed = 0;
40		- toks -= ratelimit_jiffies;
41		- spin_unlock_irqrestore(&ratelimit_lock, flags);
42		- if (lost)
43		- printk(KERN_WARNING "%s: %d messages suppressed\n",
44		- __func__, lost);
45		- return 1;
	36	+ if (time_is_before_jiffies(rs->begin + rs->interval)) {
	37	+ if (rs->missed)
	38	+ printk(KERN_WARNING "%s: %d callbacks suppressed\n",
	39	+ __func__, rs->missed);
	40	+ rs->begin = 0;
	41	+ rs->printed = 0;
	42	+ rs->missed = 0;
46	43	}
47		- missed++;
	44	+ if (rs->burst && rs->burst > rs->printed)
	45	+ goto print;
	46	+
	47	+ rs->missed++;
48	48	spin_unlock_irqrestore(&ratelimit_lock, flags);
49	49	return 0;
	50	+
	51	+print:
	52	+ rs->printed++;
	53	+ spin_unlock_irqrestore(&ratelimit_lock, flags);
	54	+ return 1;
50	55	}
51	56	EXPORT_SYMBOL(__ratelimit);
...	...	@@ -67,7 +67,7 @@
67	67	{
68	68	.ctl_name = NET_CORE_MSG_COST,
69	69	.procname = "message_cost",
70		- .data = &net_msg_cost,
	70	+ .data = &net_ratelimit_state.interval,
71	71	.maxlen = sizeof(int),
72	72	.mode = 0644,
73	73	.proc_handler = &proc_dointvec_jiffies,
...	...	@@ -76,7 +76,7 @@
76	76	{
77	77	.ctl_name = NET_CORE_MSG_BURST,
78	78	.procname = "message_burst",
79		- .data = &net_msg_burst,
	79	+ .data = &net_ratelimit_state.burst,
80	80	.maxlen = sizeof(int),
81	81	.mode = 0644,
82	82	.proc_handler = &proc_dointvec,
...	...	@@ -31,17 +31,16 @@
31	31	#include <asm/system.h>
32	32	#include <asm/uaccess.h>
33	33
34		-int net_msg_cost __read_mostly = 5*HZ;
35		-int net_msg_burst __read_mostly = 10;
36	34	int net_msg_warn __read_mostly = 1;
37	35	EXPORT_SYMBOL(net_msg_warn);
38	36
	37	+DEFINE_RATELIMIT_STATE(net_ratelimit_state, 5 * HZ, 10);
39	38	/*
40	39	* All net warning printk()s should be guarded by this function.
41	40	*/
42	41	int net_ratelimit(void)
43	42	{
44		- return __printk_ratelimit(net_msg_cost, net_msg_burst);
	43	+ return __ratelimit(&net_ratelimit_state);
45	44	}
46	45	EXPORT_SYMBOL(net_ratelimit);
47	46