Messages in this thread | | | Date | Thu, 8 May 2014 06:18:39 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] compiler.h: don't use temporary variable in __compiletime_assert() |
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On Thu, May 08, 2014 at 08:31:25AM +0200, Johannes Berg wrote: > From: Johannes Berg <johannes.berg@intel.com> > > Usually, BUG_ON and friends aren't even evaluated in sparse, but > recently compiletime_assert_atomic_type() was added, and that now > results in a sparse warning every time it is used. > > The reason turns out to be the temporary variable, after it sparse > no longer considers the value to be a constant, and results in a > warning and an error. The error is the more annoying part of this > as it suppresses any further warnings in the same file, hiding > other problems. > > Since this is all about compile time and the condition should be > side-effect free to start with, there's no downside (apart maybe > from a slight compilation time penalty?) to just duplicating it, > leaving sparse able to evaluate it at check time, getting rid of > the warning and error. > > Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> --- > include/linux/compiler.h | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/include/linux/compiler.h b/include/linux/compiler.h > index 2472740d7ab2..38c0e00ddef8 100644 > --- a/include/linux/compiler.h > +++ b/include/linux/compiler.h > @@ -324,11 +324,10 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); > > #define __compiletime_assert(condition, msg, prefix, suffix) \ > do { \ > - bool __cond = !(condition); \ > extern void prefix ## suffix(void) __compiletime_error(msg); \ > - if (__cond) \ > + if (!(condition)) \ > prefix ## suffix(); \ > - __compiletime_error_fallback(__cond); \ > + __compiletime_error_fallback(!(condition)); \ > } while (0) > > #define _compiletime_assert(condition, msg, prefix, suffix) \ > -- > 2.0.0.rc0 >
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