The patch titled
ipc: call idr_find() without locking in ipc_lock()
has been added to the -mm tree. Its filename is
ipc-call-idr_find-without-locking-in-ipc_lock.patch
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The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: ipc: call idr_find() without locking in ipc_lock()
From: Nadia Derbey <Nadia.Derbey@xxxxxxxx>
Call idr_find() locklessly from ipc_lock(), since the idr tree is now RCU
protected.
Signed-off-by: Nadia Derbey <Nadia.Derbey@xxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Jim Houston <jim.houston@xxxxxxxxxxx>
Cc: Pierre Peiffer <peifferp@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/util.c | 9 ---------
1 file changed, 9 deletions(-)
diff -puN ipc/util.c~ipc-call-idr_find-without-locking-in-ipc_lock ipc/util.c
--- a/ipc/util.c~ipc-call-idr_find-without-locking-in-ipc_lock
+++ a/ipc/util.c
@@ -688,10 +688,6 @@ void ipc64_perm_to_ipc_perm (struct ipc6
* 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 ip
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
_
Patches currently in -mm which might be from Nadia.Derbey@xxxxxxxx are
idr-change-the-idr-structure.patch
idr-rename-some-of-the-idr-apis-internal-routines.patch
idr-fix-a-printk-call.patch
idr-error-checking-factorization.patch
idr-make-idr_get_new-rcu-safe.patch
idr-make-idr_find-rcu-safe.patch
idr-make-idr_remove-rcu-safe.patch
ipc-call-idr_find-without-locking-in-ipc_lock.patch
ipc-get-rid-of-ipc_lock_down.patch
--
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