From: NeilBrown Date: Mon, 24 Jun 2024 23:04:57 +0000 (+1000) Subject: Revert "nfsd: fix oops when reading pool_stats before server is started" X-Git-Tag: for-6.11/block-post-20240722~6^2~20^2 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=ac03629b1612ad008ea6603a3d142e291e3de9bb;p=linux-2.6-block.git 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 Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever --- diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index 49a3bea33f9d..dd86d7f1e97e 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)