Re: [PATCH 1/5] knfsd: Replace lock_kernel with a mutex for nfsd thread startup/shutdown locking.

[Neil Brown <neilb@suse.de>]

On Tuesday June 10, jlayton@redhat.com wrote:
> From: Neil Brown <neilb@suse.de>
> 
> This removes the BKL from the RPC service creation codepath. The BKL
> really isn't adequate for this job since some of this info needs
> protection across sleeps.
> 
> Also, add some comments to try and clarify how the locking should work
> and to make it clear that the BKL isn't necessary as long as there is
> adequate locking between tasks when touching the svc_serv fields.
> 
> Signed-off-by: Neil Brown <neilb@suse.de>
> Signed-off-by: Jeff Layton <jlayton@redhat.com>

Thanks for proceeding with this.
As well as the fixes for this that you included in 2/5, you need this
patch as well for correctness.... Well, you need the first hunk.  The
second is unrelated but probably should be fixed.

The rest all looks good.

NeilBrown


---------------------------------

Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
 ./fs/nfsd/nfssvc.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff .prev/fs/nfsd/nfssvc.c ./fs/nfsd/nfssvc.c
--- .prev/fs/nfsd/nfssvc.c	2008-06-12 13:27:47.000000000 +1000
+++ ./fs/nfsd/nfssvc.c	2008-06-12 13:32:14.000000000 +1000
@@ -169,10 +169,12 @@ int nfsd_vers(int vers, enum vers_op cha
 
 int nfsd_nrthreads(void)
 {
-	if (nfsd_serv == NULL)
-		return 0;
-	else
-		return nfsd_serv->sv_nrthreads;
+	int rv = 0;
+	mutex_lock(&nfsd_mutex);
+	if (nfsd_serv)
+		rv = nfsd_serv->sv_nrthreads;
+	mutex_unlock(&nfsd_mutex);
+	return rv;
 }
 
 static int killsig;	/* signal that was used to kill last nfsd */
@@ -275,7 +277,7 @@ static int nfsd_init_socks(int port)
 					SVC_SOCK_DEFAULTS);
 		if (error < 0)
 			lockd_down();
-}
+	}
 	if (error < 0)
 		return error;
 	return 0;