forked from pool/glibc
28 lines
1.1 KiB
Diff
28 lines
1.1 KiB
Diff
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2018-08-27 Martin Kuchta <martin.kuchta@netapp.com>
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Torvald Riegel <triegel@redhat.com>
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[BZ #23538]
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* nptl/pthread_cond_common.c (__condvar_quiesce_and_switch_g1):
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Update r to include the set wake-request flag if waiters are
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remaining after spinning.
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Index: glibc-2.28/nptl/pthread_cond_common.c
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===================================================================
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--- glibc-2.28.orig/nptl/pthread_cond_common.c
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+++ glibc-2.28/nptl/pthread_cond_common.c
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@@ -405,8 +405,12 @@ __condvar_quiesce_and_switch_g1 (pthread
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{
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/* There is still a waiter after spinning. Set the wake-request
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flag and block. Relaxed MO is fine because this is just about
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- this futex word. */
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- r = atomic_fetch_or_relaxed (cond->__data.__g_refs + g1, 1);
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+ this futex word.
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+
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+ Update r to include the set wake-request flag so that the upcoming
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+ futex_wait only blocks if the flag is still set (otherwise, we'd
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+ violate the basic client-side futex protocol). */
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+ r = atomic_fetch_or_relaxed (cond->__data.__g_refs + g1, 1) | 1;
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if ((r >> 1) > 0)
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futex_wait_simple (cond->__data.__g_refs + g1, r, private);
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