[PATCH 5.10 757/770] lockd: drop inappropriate svc_get() from locked_get()

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5.10-stable review patch.  If anyone has any objections, please let me know.

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

From: NeilBrown <neilb@xxxxxxx>

[ Upstream commit 665e89ab7c5af1f2d260834c861a74b01a30f95f ]

The below-mentioned patch was intended to simplify refcounting on the
svc_serv used by locked.  The goal was to only ever have a single
reference from the single thread.  To that end we dropped a call to
lockd_start_svc() (except when creating thread) which would take a
reference, and dropped the svc_put(serv) that would drop that reference.

Unfortunately we didn't also remove the svc_get() from
lockd_create_svc() in the case where the svc_serv already existed.
So after the patch:
 - on the first call the svc_serv was allocated and the one reference
   was given to the thread, so there are no extra references
 - on subsequent calls svc_get() was called so there is now an extra
   reference.
This is clearly not consistent.

The inconsistency is also clear in the current code in lockd_get()
takes *two* references, one on nlmsvc_serv and one by incrementing
nlmsvc_users.   This clearly does not match lockd_put().

So: drop that svc_get() from lockd_get() (which used to be in
lockd_create_svc().

Reported-by: Ido Schimmel <idosch@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-nfs/ZHsI%2FH16VX9kJQX1@shredder/T/#u
Fixes: b73a2972041b ("lockd: move lockd_start_svc() call into lockd_create_svc()")
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Tested-by: Ido Schimmel <idosch@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/lockd/svc.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 59ef8a1f843f3..5579e67da17db 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -355,7 +355,6 @@ static int lockd_get(void)
 	int error;
 
 	if (nlmsvc_serv) {
-		svc_get(nlmsvc_serv);
 		nlmsvc_users++;
 		return 0;
 	}
-- 
2.43.0







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