Commit 983bfb7d authored by Nadia Derbey's avatar Nadia Derbey Committed by Linus Torvalds
Browse files

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: default avatarNadia Derbey <Nadia.Derbey@bull.net>
Acked-by: default avatar"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: default avatarRik van Riel <riel@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent cf481c20
...@@ -688,10 +688,6 @@ void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out) ...@@ -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. * Look for an id in the ipc ids idr and lock the associated ipc object.
* *
* The ipc object is locked on exit. * 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) 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) ...@@ -699,18 +695,13 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
struct kern_ipc_perm *out; struct kern_ipc_perm *out;
int lid = ipcid_to_idx(id); int lid = ipcid_to_idx(id);
down_read(&ids->rw_mutex);
rcu_read_lock(); rcu_read_lock();
out = idr_find(&ids->ipcs_idr, lid); out = idr_find(&ids->ipcs_idr, lid);
if (out == NULL) { if (out == NULL) {
rcu_read_unlock(); rcu_read_unlock();
up_read(&ids->rw_mutex);
return ERR_PTR(-EINVAL); return ERR_PTR(-EINVAL);
} }
up_read(&ids->rw_mutex);
spin_lock(&out->lock); spin_lock(&out->lock);
/* ipc_rmid() may have already freed the ID while ipc_lock /* ipc_rmid() may have already freed the ID while ipc_lock
......
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