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A single fix for the fallout of the recent futex uacess rework.

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With those changes GCC9 fails to analyze arch_futex_atomic_op_inuser()
 correctly and emits a 'maybe unitialized' warning. While we usually ignore
 compiler stupidity the conditional store is pointless anyway because the
 correct case has to store. For the fault case the extra store does no harm.
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Merge tag 'locking-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking fix from Thomas Gleixner:
 "A single fix for the fallout of the recent futex uacess rework.

  With those changes GCC9 fails to analyze arch_futex_atomic_op_inuser()
  correctly and emits a 'maybe unitialized' warning. While we usually
  ignore compiler stupidity the conditional store is pointless anyway
  because the correct case has to store. For the fault case the extra
  store does no harm"

* tag 'locking-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  ARM: futex: Address build warning
This commit is contained in:
Linus Torvalds 2020-05-10 11:39:31 -07:00
commit bd2049f871
1 changed files with 7 additions and 2 deletions
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9
arch/arm/include/asm/futex.h
View File

@ -165,8 +165,13 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
preempt_enable();
#endif
if (!ret)
*oval = oldval;
/*
* Store unconditionally. If ret != 0 the extra store is the least
* of the worries but GCC cannot figure out that __futex_atomic_op()
* is either setting ret to -EFAULT or storing the old value in
* oldval which results in a uninitialized warning at the call site.
*/
*oval = oldval;
return ret;
}