From 03889384cee7a198a79447c1ea6aca2c8e54d155 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Fri, 11 Dec 2009 09:48:22 -0500
Subject: tracing: Add trace_dump_stack()
I've been asked a few times about how to find out what is calling
some location in the kernel. One way is to use dynamic function tracing
and implement the func_stack_trace. But this only finds out who is
calling a particular function. It does not tell you who is calling
that function and entering a specific if conditional.
I have myself implemented a quick version of trace_dump_stack() for
this purpose a few times, and just needed it now. This is when I realized
that this would be a good tool to have in the kernel like trace_printk().
Using trace_dump_stack() is similar to dump_stack() except that it
writes to the trace buffer instead and can be used in critical locations.
For example:
@@ -5485,8 +5485,12 @@ need_resched_nonpreemptible:
if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
if (unlikely(signal_pending_state(prev->state, prev)))
prev->state = TASK_RUNNING;
- else
+ else {
deactivate_task(rq, prev, 1);
+ trace_printk("Deactivating task %s:%d\n",
+ prev->comm, prev->pid);
+ trace_dump_stack();
+ }
switch_count = &prev->nvcsw;
}
Produces:
<...>-3249 [001] 296.105269: schedule: Deactivating task ntpd:3249
<...>-3249 [001] 296.105270: <stack trace>
=> schedule
=> schedule_hrtimeout_range
=> poll_schedule_timeout
=> do_select
=> core_sys_select
=> sys_select
=> system_call_fastpath
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/kernel.h | 2 ++
1 file changed, 2 insertions(+)
(limited to 'include/linux/kernel.h')
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 3fa4c590cf1..5ad4199fb07 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -492,6 +492,8 @@ extern int
__trace_printk(unsigned long ip, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
+extern void trace_dump_stack(void);
+
/*
* The double __builtin_constant_p is because gcc will give us an error
* if we try to allocate the static variable to fmt if it is not a
--
cgit v1.2.3-70-g09d2
From e36c54582c6f14adc9e10473e2aec2cc4f0acc03 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Mon, 14 Dec 2009 15:58:33 -0500
Subject: tracing: Fix return of trace_dump_stack()
The trace_dump_stack() returned a value for a void function.
Also, added the missing stub for trace_dump_stack() when tracing is
not configured.
Reported-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <20091214162713.GA31060@elte.hu>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/kernel.h | 1 +
kernel/trace/trace.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
(limited to 'include/linux/kernel.h')
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 5ad4199fb07..f1dc752da0d 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -527,6 +527,7 @@ trace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
static inline void tracing_start(void) { }
static inline void tracing_stop(void) { }
static inline void ftrace_off_permanent(void) { }
+static inline void trace_dump_stack(void) { }
static inline int
trace_printk(const char *fmt, ...)
{
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index bd7b969a729..ee61915935d 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1158,7 +1158,7 @@ void trace_dump_stack(void)
unsigned long flags;
if (tracing_disabled || tracing_selftest_running)
- return 0;
+ return;
local_save_flags(flags);
--
cgit v1.2.3-70-g09d2
From 00b55864bb37200d7f05143c44f5e2edfc8c4578 Mon Sep 17 00:00:00 2001
From: Joe Perches <joe@perches.com>
Date: Mon, 14 Dec 2009 18:00:14 -0800
Subject: dynamic_debug.h/kernel.h: Remove KBUILD_MODNAME from dynamic_pr_debug
If CONFIG_DYNAMIC_DEBUG is enabled and a source file has:
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
dynamic_debug.h will duplicate KBUILD_MODNAME
in the output string.
Remove the use of KBUILD_MODNAME from the
output format string generated by dynamic_debug.h
If CONFIG_DYNAMIC_DEBUG is not enabled, no compile-time
check is done to printk/dev_printk arguments.
Add it.
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Jason Baron <jbaron@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/dynamic_debug.h | 13 ++++++-------
include/linux/kernel.h | 5 ++---
2 files changed, 8 insertions(+), 10 deletions(-)
(limited to 'include/linux/kernel.h')
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index a0d9422a156..f8c2e176750 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -57,8 +57,7 @@ extern int ddebug_remove_module(char *mod_name);
{ KBUILD_MODNAME, __func__, __FILE__, fmt, DEBUG_HASH, \
DEBUG_HASH2, __LINE__, _DPRINTK_FLAGS_DEFAULT }; \
if (__dynamic_dbg_enabled(descriptor)) \
- printk(KERN_DEBUG KBUILD_MODNAME ":" pr_fmt(fmt), \
- ##__VA_ARGS__); \
+ printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); \
} while (0)
@@ -69,9 +68,7 @@ extern int ddebug_remove_module(char *mod_name);
{ KBUILD_MODNAME, __func__, __FILE__, fmt, DEBUG_HASH, \
DEBUG_HASH2, __LINE__, _DPRINTK_FLAGS_DEFAULT }; \
if (__dynamic_dbg_enabled(descriptor)) \
- dev_printk(KERN_DEBUG, dev, \
- KBUILD_MODNAME ": " fmt, \
- ##__VA_ARGS__); \
+ dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__); \
} while (0)
#else
@@ -81,8 +78,10 @@ static inline int ddebug_remove_module(char *mod)
return 0;
}
-#define dynamic_pr_debug(fmt, ...) do { } while (0)
-#define dynamic_dev_dbg(dev, format, ...) do { } while (0)
+#define dynamic_pr_debug(fmt, ...) \
+ do { if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); } while (0)
+#define dynamic_dev_dbg(dev, format, ...) \
+ do { if (0) dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__); } while (0)
#endif
#endif
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 3fa4c590cf1..a93cdd031ae 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -397,9 +397,8 @@ static inline char *pack_hex_byte(char *buf, u8 byte)
printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#elif defined(CONFIG_DYNAMIC_DEBUG)
/* dynamic_pr_debug() uses pr_fmt() internally so we don't need it here */
-#define pr_debug(fmt, ...) do { \
- dynamic_pr_debug(fmt, ##__VA_ARGS__); \
- } while (0)
+#define pr_debug(fmt, ...) \
+ dynamic_pr_debug(fmt, ##__VA_ARGS__)
#else
#define pr_debug(fmt, ...) \
({ if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); 0; })
--
cgit v1.2.3-70-g09d2
From 0b2749aa6ca40ff3fe12ebb3fdf010ebad2e9085 Mon Sep 17 00:00:00 2001
From: Joe Perches <joe@perches.com>
Date: Mon, 14 Dec 2009 18:00:19 -0800
Subject: kernel.h: remove initialization of bool in printk_once
Don't initialize __print_once. Invert the test to reduce initialized
data.
defconfig before: $size vmlinux
text data bss dec hex filename
6976022 679572 1359668 9015262 898fde vmlinux
defconfig after: $size vmlinux
text data bss dec hex filename
6976006 679508 1359700 9015214 898fae vmlinux
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/kernel.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
(limited to 'include/linux/kernel.h')
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index a93cdd031ae..910db75b1a7 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -251,10 +251,10 @@ extern int printk_delay_msec;
* Print a one-time message (analogous to WARN_ONCE() et al):
*/
#define printk_once(x...) ({ \
- static bool __print_once = true; \
+ static bool __print_once; \
\
- if (__print_once) { \
- __print_once = false; \
+ if (!__print_once) { \
+ __print_once = true; \
printk(x); \
} \
})
--
cgit v1.2.3-70-g09d2
From 8a64f336bc1d4aa203b138d29d5a9c414a9fbb47 Mon Sep 17 00:00:00 2001
From: Joe Perches <joe@perches.com>
Date: Mon, 14 Dec 2009 18:00:25 -0800
Subject: kernel.h: add printk_ratelimited and pr_<level>_rl
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 <nooiwa@miraclelinux.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/kernel.h | 44 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)
(limited to 'include/linux/kernel.h')
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 910db75b1a7..4d9c916d06d 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -404,6 +404,50 @@ static inline char *pack_hex_byte(char *buf, u8 byte)
({ if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); 0; })
#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
--
cgit v1.2.3-70-g09d2
From cc8ef6eb21e964b1c5eb97b2d0e8ac9893e1bf86 Mon Sep 17 00:00:00 2001
From: Roland Dreier <rdreier@cisco.com>
Date: Fri, 15 Jan 2010 17:01:22 -0800
Subject: kernel.h: add BUILD_BUG_ON_NOT_POWER_OF_2()
Add BUILD_BUG_ON_NOT_POWER_OF_2()
When code relies on a constant being a power of 2:
#define FOO 512 /* must be a power of 2 */
it would be nice to be able to do:
BUILD_BUG_ON(!is_power_of_2(FOO));
However applying an inline function does not result in a compile-time
constant that can be used with BUILD_BUG_ON(), so trying that gives
results in:
error: bit-field '<anonymous>' width not an integer constant
As suggested by akpm, rather than monkeying around with is_power_of_2()
and risking gcc warts about constant expressions, just create a macro
BUILD_BUG_ON_NOT_POWER_OF_2() to encapsulate this common requirement.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: David Dillow <dave@thedillows.org>
Cc: "Robert P. J. Day" <rpjday@crashcourse.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/kernel.h | 4 ++++
1 file changed, 4 insertions(+)
(limited to 'include/linux/kernel.h')
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 3fc9f5aab5f..328bca609b9 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -734,6 +734,10 @@ struct sysinfo {
/* Force a compilation error if condition is constant and true */
#define MAYBE_BUILD_BUG_ON(cond) ((void)sizeof(char[1 - 2 * !!(cond)]))
+/* Force a compilation error if a constant expression is not a power of 2 */
+#define BUILD_BUG_ON_NOT_POWER_OF_2(n) \
+ BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
+
/* Force a compilation error if condition is true, but also produce a
result (of value 0 and type size_t), so the expression can be used
e.g. in a structure initializer (or where-ever else comma expressions
--
cgit v1.2.3-70-g09d2