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authorRafael Aquini <aquini@redhat.com>2014-01-27 17:07:01 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-27 21:02:39 -0800
commit0f3d2b0135f4bdbfe47a99753923a64efd373d11 (patch)
tree4b211b7502e2412aedd94400bdcb012a2b5814b3 /ipc/msg.c
parent78f5009cc35eb5e52d276a046d90ee2f41b60f8c (diff)
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ipc: introduce ipc_valid_object() helper to sort out IPC_RMID races
After the locking semantics for the SysV IPC API got improved, a couple of IPC_RMID race windows were opened because we ended up dropping the 'kern_ipc_perm.deleted' check performed way down in ipc_lock(). The spotted races got sorted out by re-introducing the old test within the racy critical sections. This patch introduces ipc_valid_object() to consolidate the way we cope with IPC_RMID races by using the same abstraction across the API implementation. Signed-off-by: Rafael Aquini <aquini@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Greg Thelen <gthelen@google.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/msg.c')
-rw-r--r--ipc/msg.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/ipc/msg.c b/ipc/msg.c
index 558aa91186b6..8983ea57d970 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -696,7 +696,7 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext,
goto out_unlock0;
/* raced with RMID? */
- if (msq->q_perm.deleted) {
+ if (!ipc_valid_object(&msq->q_perm)) {
err = -EIDRM;
goto out_unlock0;
}
@@ -731,7 +731,8 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext,
ipc_lock_object(&msq->q_perm);
ipc_rcu_putref(msq, ipc_rcu_free);
- if (msq->q_perm.deleted) {
+ /* raced with RMID? */
+ if (!ipc_valid_object(&msq->q_perm)) {
err = -EIDRM;
goto out_unlock0;
}
@@ -909,7 +910,7 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgfl
ipc_lock_object(&msq->q_perm);
/* raced with RMID? */
- if (msq->q_perm.deleted) {
+ if (!ipc_valid_object(&msq->q_perm)) {
msg = ERR_PTR(-EIDRM);
goto out_unlock0;
}