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authorLinus Torvalds <torvalds@linux-foundation.org>2016-02-17 11:35:41 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-02-17 11:35:41 -0800
commita9f70bd4e787191ca27941e4dd9c1de00593fb58 (patch)
parent65c23c65bee479faceb042a52f5a7278dfa8d972 (diff)
parentb33c8ff4431a343561e2319f17c14286f2aa52e2 (diff)
Merge tag 'trace-fixes-v4.5-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt: "This includes two fixes. The first is something that has come up a few times and has been worked out individually, but it's come up now enough that the problem should be generic. Tracepoints are protected by RCU sched. There are several tracepoints within core infrastructure like kfree(). If a tracepoint is called when the CPU is going down, or when it's coming up but has yet to be recognized by RCU, a RCU warning is triggered. This is a true bug as that tracepoint is not protected by RCU. Usually, this is taken care of by testing for cpu online as a tracepoint condition. But as this is happening more often, moving it from a individual tracepoint to a check in the tracepoint infrastructure is more robust. Note, there is now a duplicate of a cpu online test, because this update does not remove the individual checks. But the overhead is small enough that the removal can be done in another release. The second change is strange linker breakage due to the branch tracer's builtin_constant_p() check failing, and treating the condition as a variable instead of a constant. Arnd Bergmann found that this can be fixed by testing !!(cond) instead of just (cond)" * tag 'trace-fixes-v4.5-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Fix freak link error caused by branch tracer tracepoints: Do not trace when cpu is offline
2 files changed, 6 insertions, 1 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 00b042c49ccd..48f5aab117ae 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -144,7 +144,7 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
#define __trace_if(cond) \
- if (__builtin_constant_p((cond)) ? !!(cond) : \
+ if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
({ \
int ______r; \
static struct ftrace_branch_data \
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index acd522a91539..acfdbf353a0b 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -14,8 +14,10 @@
* See the file COPYING for more details.
+#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/types.h>
+#include <linux/cpumask.h>
#include <linux/rcupdate.h>
#include <linux/tracepoint-defs.h>
@@ -132,6 +134,9 @@ extern void syscall_unregfunc(void);
void *it_func; \
void *__data; \
+ if (!cpu_online(raw_smp_processor_id())) \
+ return; \
+ \
if (!(cond)) \
return; \
prercu; \