From 983bfb7db303cfde56ae5bbf4e0f2f46e38c9576 Mon Sep 17 00:00:00 2001 From: Nadia Derbey Date: Fri, 25 Jul 2008 01:48:03 -0700 Subject: [PATCH] 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 Acked-by: "Paul E. McKenney" Cc: Manfred Spraul Cc: Jim Houston Cc: Pierre Peiffer Acked-by: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- ipc/util.c | 9 --------- 1 file changed, 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 -- 2.20.1