nfsd: Fix a soft lockup race in nfsd_file_mark_find_or_create()
[ Upstream commit 90d2f1da83
]
If nfsd_file_mark_find_or_create() keeps winning the race for the
nfsd_file_fsnotify_group->mark_mutex against nfsd_file_mark_put()
then it can soft lock up, since fsnotify_add_inode_mark() ends
up always finding an existing entry.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
parent
4f726a2afb
commit
fed639f7e1
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@ -133,9 +133,13 @@ nfsd_file_mark_find_or_create(struct nfsd_file *nf)
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struct nfsd_file_mark,
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nfm_mark));
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mutex_unlock(&nfsd_file_fsnotify_group->mark_mutex);
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fsnotify_put_mark(mark);
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if (likely(nfm))
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if (nfm) {
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fsnotify_put_mark(mark);
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break;
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}
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/* Avoid soft lockup race with nfsd_file_mark_put() */
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fsnotify_destroy_mark(mark, nfsd_file_fsnotify_group);
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fsnotify_put_mark(mark);
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} else
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mutex_unlock(&nfsd_file_fsnotify_group->mark_mutex);
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