Date: Tue, 3 Jul 2007 17:42:37 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/fs/devfs devfs_int.h devfs_vnops.c src/sys/kern kern_conf.c src/sys/sys conf.h Message-ID: <200707031742.l63HgbY9096657@repoman.freebsd.org>
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kib 2007-07-03 17:42:37 UTC
FreeBSD src repository
Modified files:
sys/fs/devfs devfs_int.h devfs_vnops.c
sys/kern kern_conf.c
sys/sys conf.h
Log:
Since rev. 1.199 of sys/kern/kern_conf.c, the thread that calls
destroy_dev() from d_close() cdev method would self-deadlock.
devfs_close() bump device thread reference counter, and destroy_dev()
sleeps, waiting for si_threadcount to reach zero for cdev without
d_purge method.
destroy_dev_sched() could be used instead from d_close(), to
schedule execution of destroy_dev() in another context. The
destroy_dev_sched_drain() function can be used to drain the scheduled
calls to destroy_dev_sched(). Similarly, drain_dev_clone_events() drains
the events clone to make sure no lingering devices are left after
dev_clone event handler deregistered.
make_dev_credf(MAKEDEV_REF) function should be used from dev_clone
event handlers instead of make_dev()/make_dev_cred() to ensure that created
device has reference counter bumped before cdev mutex is dropped inside
make_dev().
Reviewed by: tegge (early versions), njl (programming interface)
Debugging help and testing by: Peter Holm
Approved by: re (kensmith)
Revision Changes Path
1.4 +6 -0 src/sys/fs/devfs/devfs_int.h
1.148 +13 -0 src/sys/fs/devfs/devfs_vnops.c
1.204 +147 -18 src/sys/kern/kern_conf.c
1.233 +10 -0 src/sys/sys/conf.h
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