printk: pr_debug_ratelimited: check state first to reduce "callbacks suppressed" messages (29fc2bc7) · Commits · 戴 / test

pr_debug_ratelimited should be coded similarly to dev_dbg_ratelimited to reduce the "callbacks suppressed" messages. Add #include <linux/dynamic_debug.h> to printk.h. Unfortunately, this new #include must be after the prototype/declaration of function printk. It may be better to split out these _ratelimited declarations into a separate file one day. Any use of these pr_<foo>_ratelimited functions must also have another specific #include <ratelimited.h>. Most users have this done indirectly via #include <linux/kernel.h> printk.h may not #include <linux/ratelimit.h> as it causes circular dependencies and compilation failures. Signed-off-by:

Joe Perches <joe@perches.com> Tested-by:

Krzysztof Mazur <krzysiek@podlesie.net> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/printk.h

+15 −1

Original line number	Diff line number	Diff line
		@@ -233,6 +233,8 @@ extern asmlinkage void dump_stack(void) __cold;
		no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
		#endif

		#include <linux/dynamic_debug.h>

		/* If you are writing a driver, please use dev_dbg instead */
		#if defined(CONFIG_DYNAMIC_DEBUG)
		/* dynamic_pr_debug() uses pr_fmt() internally so we don't need it here */
		@@ -343,7 +345,19 @@ extern asmlinkage void dump_stack(void) __cold;
		#endif

		/* If you are writing a driver, please use dev_dbg instead */
		#if defined(DEBUG)
		#if defined(CONFIG_DYNAMIC_DEBUG)
		/* descriptor check is first to prevent flooding with "callbacks suppressed" */
		#define pr_debug_ratelimited(fmt, ...) \
		do { \
		static DEFINE_RATELIMIT_STATE(_rs, \
		DEFAULT_RATELIMIT_INTERVAL, \
		DEFAULT_RATELIMIT_BURST); \
		DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt); \
		if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT) && \
		__ratelimit(&_rs)) \
		__dynamic_pr_debug(&descriptor, fmt, ##__VA_ARGS__); \
		} while (0)
		#elif defined(DEBUG)
		#define pr_debug_ratelimited(fmt, ...) \
		printk_ratelimited(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
		#else

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