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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>
This commit is contained in:
Nadia Derbey 2008-07-25 01:48:03 -07:00 committed by Linus Torvalds
parent cf481c20c4
commit 983bfb7db3
1 changed files with 0 additions and 9 deletions
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9
ipc/util.c
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@ -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