cvs commit: src/sys/fs/devfs devfs_int.h devfs_vnops.c src/sys/kern kern_conf.c src/sys/sys conf.h

[Nate Lawson]

Konstantin Belousov wrote:
> 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

Thanks for all your work on this.  Now to review all callers of
destroy_dev() to see if they should use the simpler interface.

-- 
Nate