Date: Tue, 30 Nov 2004 12:02:53 +0000 (UTC) From: David Xu <davidxu@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/kern kern_umtx.c Message-ID: <200411301202.iAUC2rAd085211@repoman.freebsd.org>
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davidxu 2004-11-30 12:02:53 UTC
FreeBSD src repository
Modified files:
sys/kern kern_umtx.c
Log:
1. use per-chain mutex instead of global mutex to reduce
lock collision.
2. Fix two race conditions. One is between _umtx_unlock and signal,
also a thread was marked TDF_UMTXWAKEUP by _umtx_unlock, it is
possible a signal delivered to the thread will cause msleep
returns EINTR, and the thread breaks out of loop, this causes
umtx ownership is not transfered to the thread. Another is in
_umtx_unlock itself, when the function sets the umtx to
UMTX_UNOWNED state, a new thread can come in and lock the umtx,
also the function tries to set contested bit flag, but it will
fail. Although the function will wake a blocked thread, if that
thread breaks out of loop by signal, no contested bit will be set.
Revision Changes Path
1.17 +212 -115 src/sys/kern/kern_umtx.c
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