On Thu, Jun 18, 2009 at 10:39:10AM -0700, Labiaga, Ricardo wrote: > On 6/18/09 10:31 AM, "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: > > > On Wed, Jun 17, 2009 at 06:50:45PM -0700, Ricardo Labiaga wrote: > >> renew_client() manipulates the client queue for lease renewal. Need to > >> obtain the client_mutex before manipulating it. > >> > >> Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@xxxxxxxxxx> > >> --- > >> fs/nfsd/nfs4state.c | 2 ++ > >> 1 files changed, 2 insertions(+), 0 deletions(-) > >> > >> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > >> index 4cb5d1d..18258d7 100644 > >> --- a/fs/nfsd/nfs4state.c > >> +++ b/fs/nfsd/nfs4state.c > >> @@ -1537,7 +1537,9 @@ replay_cache: > >> * Hold a session reference until done processing the compound: > >> * nfsd4_put_session called only if the cstate slot is set. > >> */ > >> + nfs4_lock_state(); > >> renew_client(session->se_client); > >> + nfs4_unlock_state(); > >> nfsd4_get_session(session); > >> out: > >> spin_unlock(&sessionid_lock); > > > > We can't take a mutex while handling a spinlock. (And you should have > > gotten warnings about this--not sure what kernel hacking config options > > you may need turned on for that.) > > > > Ah, OK. I didn't know that. The deadlock: Task 1 takes a spinlock. Task 1 sleeps on the mutex. Task 2 is scheduled in. Task 2 requests the same spinlock, spins. Now Task 2 is spinning waiting for the spinlock, keeping task 1 from getting the cpu back and releaseing the spinlock. So, no sleeping under spinlocks. > > Possible hack: add a spinlock that for now will just cover the client > > lru? > > Let me study this some more and see if I can simply drop the sessionid > spinlock before renewing the state. OK. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
