Date: Fri, 21 Nov 1997 22:10:37 -0800 (PST) From: Bruce Evans <bde@FreeBSD.ORG> To: cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG, cvs-sys@FreeBSD.ORG Subject: cvs commit: src/sys/kern vfs_syscalls.c Message-ID: <199711220610.WAA11558@freefall.freebsd.org>
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bde 1997/11/21 22:10:37 PST
Modified files:
sys/kern vfs_syscalls.c
Log:
Fixed rev.1.81. mp->mnt_kern_flag was restored in the non-error case of
`mount -u'. This only matters for `mount -u' competing with unmounts.
If I understand the locking correctly: if mount() blocks, then unmount()
may run and set mp->kern_flag for the same mp. Then unmount() blocks
waiting for mount() to finish. When unmount() continues, its MNTK flags
(MNTK_UNMOUNT and MNTK_MWAIT) may have been clobbered.
Didn't fix old bugs:
- restoring mp->mnt_kern_flag is wrong for the same reasons in the error
case.
- the error case of unmount() seems to be broken too:
(a) MNTK_UNMOUNT gets clobbered, although another unmount() may have
set it. Perhaps it shouldn't be set until after the full lock is
aquired.
(b) MNTK_MWAIT isn't honoured.
Fixed a nearby style bug.
Revision Changes Path
1.83 +4 -3 src/sys/kern/vfs_syscalls.c
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