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| author | Nadia Derbey <Nadia.Derbey@bull.net> | 2008-07-25 01:48:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-07-25 10:53:42 -0700 |
| commit | 983bfb7db303cfde56ae5bbf4e0f2f46e38c9576 (patch) | |
| tree | d107ca3c03e2c84e3d58c6f9e53879d3486e9c5f /ipc/util.c | |
| parent | cf481c20c476ad2c0febdace9ce23f5a4db19582 (diff) | |
| download | lwn-983bfb7db303cfde56ae5bbf4e0f2f46e38c9576.tar.gz lwn-983bfb7db303cfde56ae5bbf4e0f2f46e38c9576.zip | |
ipc: call idr_find() without locking in ipc_lock()
Call idr_find() locklessly from ipc_lock(), since the idr tree is now RCU
protected.
Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Jim Houston <jim.houston@comcast.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/util.c')
| -rw-r--r-- | ipc/util.c | 9 |
1 files changed, 0 insertions, 9 deletions
diff --git a/ipc/util.c b/ipc/util.c index 3339177b336c..0f468c34e83c 100644 --- a/ipc/util.c +++ b/ipc/util.c @@ -688,10 +688,6 @@ void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out) * Look for an id in the ipc ids idr and lock the associated ipc object. * * The ipc object is locked on exit. - * - * This is the routine that should be called when the rw_mutex is not already - * held, i.e. idr tree not protected: it protects the idr tree in read mode - * during the idr_find(). */ struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) @@ -699,18 +695,13 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) struct kern_ipc_perm *out; int lid = ipcid_to_idx(id); - down_read(&ids->rw_mutex); - rcu_read_lock(); out = idr_find(&ids->ipcs_idr, lid); if (out == NULL) { rcu_read_unlock(); - up_read(&ids->rw_mutex); return ERR_PTR(-EINVAL); } - up_read(&ids->rw_mutex); - spin_lock(&out->lock); /* ipc_rmid() may have already freed the ID while ipc_lock |