Re: [23/27] kernel.h: add printk_ratelimited and pr_<level>_rl

On Tue, 2012-01-24 at 16:46 +0200, Phil Carmody wrote:

On 23/01/12 15:41 -0800, ext Greg KH wrote:

quoted

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

This looks like an added feature with no users in .32 - does it really 
belong in a stable tree?
(But to be explicit, I have no issue with its contents at all.)

It's required for commit 0bfc96cb77224736dfa35c3c555d37b3646ef35e
('block: fail SCSI passthrough ioctls on partition devices'), though
that hasn't actually been included in this series.  I think that's
because there is still ongoing discussion of which error codes need to
be used.

Ben.

Phil

quoted

------------------


From: Joe Perches <joe@perches.com>

commit 8a64f336bc1d4aa203b138d29d5a9c414a9fbb47 upstream.

Add a printk_ratelimited statement expression macro that uses a per-call
ratelimit_state so that multiple subsystems output messages are not
suppressed by a global __ratelimit state.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: s/_rl/_ratelimited/g]
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Naohiro Ooiwa <redacted>
Cc: Ingo Molnar <redacted>
Cc: Hiroshi Shimamoto <redacted>
Cc: Peter Zijlstra <redacted>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 include/linux/kernel.h |   44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h

@@ -407,6 +407,50 @@ static inline char *pack_hex_byte(char *
 #endif
 
 /*
+ * ratelimited messages with local ratelimit_state,
+ * no local ratelimit_state used in the !PRINTK case
+ */
+#ifdef CONFIG_PRINTK
+#define printk_ratelimited(fmt, ...)  ({		\
+	static struct ratelimit_state _rs = {		\
+		.interval = DEFAULT_RATELIMIT_INTERVAL, \
+		.burst = DEFAULT_RATELIMIT_BURST,       \
+	};                                              \
+							\
+	if (!__ratelimit(&_rs))                         \
+		printk(fmt, ##__VA_ARGS__);		\
+})
+#else
+/* No effect, but we still get type checking even in the !PRINTK case: */
+#define printk_ratelimited printk
+#endif
+
+#define pr_emerg_ratelimited(fmt, ...) \
+	printk_ratelimited(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_alert_ratelimited(fmt, ...) \
+	printk_ratelimited(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_crit_ratelimited(fmt, ...) \
+	printk_ratelimited(KERN_CRIT pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_err_ratelimited(fmt, ...) \
+	printk_ratelimited(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_warning_ratelimited(fmt, ...) \
+	printk_ratelimited(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_notice_ratelimited(fmt, ...) \
+	printk_ratelimited(KERN_NOTICE pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_info_ratelimited(fmt, ...) \
+	printk_ratelimited(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
+/* no pr_cont_ratelimited, don't do that... */
+/* If you are writing a driver, please use dev_dbg instead */
+#if defined(DEBUG)
+#define pr_debug_ratelimited(fmt, ...) \
+	printk_ratelimited(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
+#else
+#define pr_debug_ratelimited(fmt, ...) \
+	({ if (0) printk_ratelimited(KERN_DEBUG pr_fmt(fmt), \
+				     ##__VA_ARGS__); 0; })
+#endif
+
+/*
  * General tracing related utility functions - trace_printk(),
  * tracing_on/tracing_off and tracing_start()/tracing_stop
  *


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-- 
Ben Hutchings
Horngren's Observation:
                   Among economists, the real world is often a special case.