Date: Sat, 14 Mar 2009 01:12:35 +0000 (UTC) From: Bruce M Simpson <bms@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-7@freebsd.org Subject: svn commit: r189781 - stable/7/sys/kern Message-ID: <200903140112.n2E1CZmM077949@svn.freebsd.org>
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Author: bms Date: Sat Mar 14 01:12:35 2009 New Revision: 189781 URL: http://svn.freebsd.org/changeset/base/189781 Log: MFC rev: 189736 Ensure that the semaphore value is re-checked after sem_lock is re-acquired, after the condition variable is signalled. Early MFC, as the test case in the PR is fairly complete and the submitter also re-ran test case on -STABLE. It also bites Python fairly hard, which will otherwise try to use POSIX sems for its internal thread synchronization; this needs more in-depth testing. PR: http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/127545 Reviewed by: attilio Modified: stable/7/sys/kern/uipc_sem.c Modified: stable/7/sys/kern/uipc_sem.c ============================================================================== --- stable/7/sys/kern/uipc_sem.c Sat Mar 14 00:33:08 2009 (r189780) +++ stable/7/sys/kern/uipc_sem.c Sat Mar 14 01:12:35 2009 (r189781) @@ -722,7 +722,7 @@ kern_sem_wait(struct thread *td, semid_t #endif DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag)); vfs_timestamp(&ks->ks_atime); - if (ks->ks_value == 0) { + while (ks->ks_value == 0) { ks->ks_waiters++; if (tryflag != 0) error = EAGAIN;
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