tree e3dedbffebd4f0e15da97684500296c9bc4d3d6a
parent f6a592e8abd2f2394623ce5427cbb4c265495974
author Trond Myklebust <Trond.Myklebust@netapp.com> 1190750103 -0400
committer Linus Torvalds <torvalds@woody.linux-foundation.org> 1190823724 -0700

NLM: Fix a circular lock dependency in lockd

The problem is that the garbage collector for the 'host' structures
nlm_gc_hosts(), holds nlm_host_mutex while calling down to
nlmsvc_mark_resources, which, eventually takes the file->f_mutex.

We cannot therefore call nlmsvc_lookup_host() from within
nlmsvc_create_block, since the caller will already hold file->f_mutex, so
the attempt to grab nlm_host_mutex may deadlock.

Fix the problem by calling nlmsvc_lookup_host() outside the file->f_mutex.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>