From ac03629b1612ad008ea6603a3d142e291e3de9bb Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.de>
Date: Tue, 25 Jun 2024 09:04:57 +1000
Subject: [PATCH] Revert "nfsd: fix oops when reading pool_stats before server
is started"
This reverts commit 8e948c365d9c10b685d1deb946bd833d6a9b43e0.
The reverted commit moves a test on a field protected by a mutex outside
of the protection of that mutex, and so is obviously racey.
Depending on how the race goes, si->serv might be NULL when dereferenced
in svc_pool_stats_start(), or svc_pool_stats_stop() might unlock a mutex
that hadn't been locked.
This bug that the commit tried to fix has been addressed by initialising
->mutex earlier.
Fixes: 8e948c365d9c ("nfsd: fix oops when reading pool_stats before server is started")
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
net/sunrpc/svc_xprt.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 49a3bea33f9d5..dd86d7f1e97e9 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -1421,13 +1421,12 @@ static void *svc_pool_stats_start(struct seq_file *m, loff_t *pos)
dprintk("svc_pool_stats_start, *pidx=%u\n", pidx);
- if (!si->serv)
- return NULL;
-
mutex_lock(si->mutex);
if (!pidx)
return SEQ_START_TOKEN;
+ if (!si->serv)
+ return NULL;
return pidx > si->serv->sv_nrpools ? NULL
: &si->serv->sv_pools[pidx - 1];
}
@@ -1459,8 +1458,7 @@ static void svc_pool_stats_stop(struct seq_file *m, void *p)
{
struct svc_info *si = m->private;
- if (si->serv)
- mutex_unlock(si->mutex);
+ mutex_unlock(si->mutex);
}
static int svc_pool_stats_show(struct seq_file *m, void *p)
--
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