From: Mike Frysinger Date: Tue, 28 Jul 2015 06:19:49 +0000 (-0400) Subject: ia64: atomic.h: fix atomic_exchange_and_add 64bit handling X-Git-Tag: glibc-2.22~16 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cf31a2c79957936b60de34ea1e718e892baf669c;p=thirdparty%2Fglibc.git ia64: atomic.h: fix atomic_exchange_and_add 64bit handling Way back in 2005 the atomic_exchange_and_add function was cleaned up to avoid the explicit size checking and instead let gcc handle things itself. Unfortunately that change ended up leaving beyond a cast to int, even when the incoming value was a long. This has flown under the radar for a long time due to the function not being heavily used in the tree (especially as a full 64bit field), but a recent change to semaphores made some nptl tests fail reliably. This is due to the code packing two 32bit values into one 64bit variable (where the high 32bits contained the number of waiters), and then the whole variable being atomically updated between threads. On ia64, that meant we never atomically updated the count, so sometimes the sem_post would not wake up the waiters. --- diff --git a/ChangeLog b/ChangeLog index b177adc143b..cd2d8274c7d 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,8 @@ +2015-07-27 Mike Frysinger + + * sysdeps/ia64/bits/atomic.h (atomic_exchange_and_add): Define + directly in terms of __sync_fetch_and_add and delete (int) cast. + 2015-07-27 Mike Frysinger * sysdeps/unix/sysv/linux/ia64/Makefile (CPPFLAGS): Delete diff --git a/sysdeps/ia64/bits/atomic.h b/sysdeps/ia64/bits/atomic.h index 0e9dfc71746..4c2b54094c1 100644 --- a/sysdeps/ia64/bits/atomic.h +++ b/sysdeps/ia64/bits/atomic.h @@ -82,9 +82,7 @@ typedef uintmax_t uatomic_max_t; (__sync_synchronize (), __sync_lock_test_and_set (mem, value)) #define atomic_exchange_and_add(mem, value) \ - ({ __typeof (*mem) __result; \ - __result = __sync_fetch_and_add ((mem), (int) (value)); \ - __result; }) + __sync_fetch_and_add ((mem), (value)) #define atomic_decrement_if_positive(mem) \ ({ __typeof (*mem) __oldval, __val; \