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>
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@ -114,7 +114,9 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
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* "Define 'is'", Bill Clinton
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* "Define 'if'", Steven Rostedt
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*/
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#define if(cond) if (__builtin_constant_p((cond)) ? !!(cond) : \
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#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
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#define __trace_if(cond) \
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if (__builtin_constant_p((cond)) ? !!(cond) : \
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({ \
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int ______r; \
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static struct ftrace_branch_data \
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