If we have two tasks racing to update a mirror's credentials, then they
can end up leaking one (or more) sets of credentials. The first task
will set mirror->cred and then the second task will just overwrite it.
Use a cmpxchg to ensure that the creds are only set once. If we get to
the point where we would set mirror->cred and find that they're already
set, then we just release the creds that were just found.
Signed-off-by: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx>
---
fs/nfs/flexfilelayout/flexfilelayoutdev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/nfs/flexfilelayout/flexfilelayoutdev.c b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
index 77a2d026aa12..c19b9a88f748 100644
--- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c
+++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
@@ -324,7 +324,8 @@ static int ff_layout_update_mirror_cred(struct nfs4_ff_layout_mirror *mirror,
__func__, PTR_ERR(cred));
return PTR_ERR(cred);
} else {
- mirror->cred = cred;
+ if (cmpxchg(&mirror->cred, NULL, cred))
+ put_rpccred(cred);
}
}
return 0;
--
2.4.3
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