diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-07 07:59:41 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-07 09:05:35 -0700 |
| commit | aeeae86859f4319de0a4946b44771d9926eeed54 (patch) | |
| tree | 2a9520601922a930259a18b666dc2281e8262def /include | |
| parent | 985c0cd3f75b5a546ceab002e36b4263f2f7d2c3 (diff) | |
| download | lwn-aeeae86859f4319de0a4946b44771d9926eeed54.tar.gz lwn-aeeae86859f4319de0a4946b44771d9926eeed54.zip | |
Fix build errors due to CONFIG_BRANCH_TRACER=y
The code that enables branch tracing for all (non-constant) branches
plays games with the preprocessor and #define's the C 'if ()' construct
to do tracing.
That's all fine, but it fails for some unusual but valid C code that is
sometimes used in macros, notably by the intel-iommu code:
if (i=drhd->iommu, drhd->ignored) ..
because now the preprocessor complains about multiple arguments to the
'if' macro.
So make the macro expansion of this particularly horrid trick use
varargs, and handle the case of comma-expressions in if-statements. Use
another macro to do it cleanly in just one place.
This replaces a patch by David (and acked by Steven) that did this all
inside that one already-too-horrid macro.
Tested-by: Ingo Molnar <mingo@elte.hu>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/compiler.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 6faa7e549de4..cebfdcd3dbdd 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -114,7 +114,9 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); * "Define 'is'", Bill Clinton * "Define 'if'", Steven Rostedt */ -#define if(cond) if (__builtin_constant_p((cond)) ? !!(cond) : \ +#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) ) +#define __trace_if(cond) \ + if (__builtin_constant_p((cond)) ? !!(cond) : \ ({ \ int ______r; \ static struct ftrace_branch_data \ |