Messages in this thread | | | Subject | Re: stable/linux-3.16.y build: 178 builds: 1 failed, 177 passed, 2 errors, 57 warnings (v3.16.52) | From | Manfred Spraul <> | Date | Sat, 13 Jan 2018 19:51:06 +0100 |
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Hi Arnd,
On 01/03/2018 12:15 AM, Arnd Bergmann wrote: > >> 2 ipc/sem.c:377:6: warning: '___p1' may be used uninitialized in this function [-Wmaybe-uninitialized] > This code was last touched in 3.16 by the backport of commit > 5864a2fd3088 ("ipc/sem.c: fix complex_count vs. simple op race") > > The warning is in "smp_load_acquire(&sma->complex_mode))", and I suspect > that commit 27d7be1801a4 ("ipc/sem.c: avoid using spin_unlock_wait()") > avoided the warning upstream by removing the smp_mb() before it. The smp_mb() pairs with spin_unlock_wait() in complexmode_enter() It is removed by commit 27d7be1801a4 ("ipc/sem.c: avoid using spin_unlock_wait()").
From what I see, it doesn't exist in any of the stable kernels (intentionally, the above commit is a rewrite for better performance).
___p1 is from smp_load_acquire() > typeof(*p) ___p1 = READ_ONCE(*p); \
I don't see how ___p1 could be used uninitialized. Perhaps a compiler issue?
-- Manfred
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