From aeeae86859f4319de0a4946b44771d9926eeed54 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 7 Apr 2009 07:59:41 -0700 Subject: [PATCH] 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 Cc: David Woodhouse Cc: Steven Rostedt Signed-off-by: Linus Torvalds --- include/linux/compiler.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 6faa7e549de4c2..cebfdcd3dbddc3 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 \