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>

2 files changed, 5 insertions, 16 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index 3f7a2a9..a7f7559 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -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);
 
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 1a8299d..35a50db 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -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,