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From:   NeilBrown <neilb@suse.de>
To:     Chuck Lever <chuck.lever@oracle.com>,
        Jeff Layton <jlayton@kernel.org>
Cc:     linux-nfs@vger.kernel.org, Olga Kornievskaia <kolga@netapp.com>,
        Dai Ngo <Dai.Ngo@oracle.com>, Tom Talpey <tom@talpey.com>
Subject: [PATCH 3/5] nfsd: hold nfsd_mutex across entire netlink operation
Date:   Mon, 30 Oct 2023 12:08:36 +1100
Message-ID: <20231030011247.9794-4-neilb@suse.de>
In-Reply-To: <20231030011247.9794-1-neilb@suse.de>
References: <20231030011247.9794-1-neilb@suse.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
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Rather than using svc_get() and svc_put() to hold a stable reference to
the nfsd_svc for netlink lookups, simply hold the mutex for the entire
time.

The "entire" time isn't very long, and the mutex is not often contented.

This makes way for use to remove the refcounts of svc, which is more
confusing than useful.

Signed-off-by: NeilBrown <neilb@suse.de>
---
 fs/nfsd/nfsctl.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index d78ae4452946..8f644f1d157c 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1515,11 +1515,10 @@ int nfsd_nl_rpc_status_get_start(struct netlink_callback *cb)
 	int ret = -ENODEV;
 
 	mutex_lock(&nfsd_mutex);
-	if (nn->nfsd_serv) {
-		svc_get(nn->nfsd_serv);
+	if (nn->nfsd_serv)
 		ret = 0;
-	}
-	mutex_unlock(&nfsd_mutex);
+	else
+		mutex_unlock(&nfsd_mutex);
 
 	return ret;
 }
@@ -1691,8 +1690,6 @@ int nfsd_nl_rpc_status_get_dumpit(struct sk_buff *skb,
  */
 int nfsd_nl_rpc_status_get_done(struct netlink_callback *cb)
 {
-	mutex_lock(&nfsd_mutex);
-	nfsd_put(sock_net(cb->skb->sk));
 	mutex_unlock(&nfsd_mutex);
 
 	return 0;
-- 
2.42.0