From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Elder Subject: [PATCH] rbd: add barriers near done flag operations Date: Wed, 06 Feb 2013 09:19:05 -0600 Message-ID: <51127469.1070903@inktank.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ie0-f169.google.com ([209.85.223.169]:54686 "EHLO mail-ie0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756633Ab3BFPTI (ORCPT ); Wed, 6 Feb 2013 10:19:08 -0500 Received: by mail-ie0-f169.google.com with SMTP id 13so2105219iea.0 for ; Wed, 06 Feb 2013 07:19:08 -0800 (PST) Sender: ceph-devel-owner@vger.kernel.org List-ID: To: ceph-devel@vger.kernel.org Somehow, I missed this little item in Documentation/atomic_ops.txt: *** WARNING: atomic_read() and atomic_set() DO NOT IMPLY BARRIERS! *** Create and use some helper functions that include the proper memory barriers for manipulating the done field. Signed-off-by: Alex Elder --- drivers/block/rbd.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 91983a60..982963e 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -1216,10 +1216,28 @@ static int rbd_obj_request_wait(struct rbd_obj_request *obj_request) return wait_for_completion_interruptible(&obj_request->completion); } +static void obj_request_done_init(struct rbd_obj_request *obj_request) +{ + atomic_set(&obj_request->done, 0); + smp_wmb(); +} + +static void obj_request_done_set(struct rbd_obj_request *obj_request) +{ + atomic_set(&obj_request->done, 1); + smp_wmb(); +} + +static bool obj_request_done_test(struct rbd_obj_request *obj_request) +{ + smp_rmb(); + return atomic_read(&obj_request->done) != 0; +} + static void rbd_osd_trivial_callback(struct rbd_obj_request *obj_request, struct ceph_osd_op *op) { - atomic_set(&obj_request->done, 1); + obj_request_done_set(obj_request); } static void rbd_obj_request_complete(struct rbd_obj_request *obj_request) @@ -1249,14 +1267,14 @@ static void rbd_osd_read_callback(struct rbd_obj_request *obj_request, xferred = obj_request->length; } obj_request->xferred = xferred; - atomic_set(&obj_request->done, 1); + obj_request_done_set(obj_request); } static void rbd_osd_write_callback(struct rbd_obj_request *obj_request, struct ceph_osd_op *op) { obj_request->xferred = le64_to_cpu(op->extent.length); - atomic_set(&obj_request->done, 1); + obj_request_done_set(obj_request); } static void rbd_osd_req_callback(struct ceph_osd_request *osd_req, @@ -1300,7 +1318,7 @@ static void rbd_osd_req_callback(struct ceph_osd_request *osd_req, break; } - if (atomic_read(&obj_request->done)) + if (obj_request_done_test(obj_request)) rbd_obj_request_complete(obj_request); } @@ -1407,7 +1425,7 @@ static struct rbd_obj_request *rbd_obj_request_create(const char *object_name, obj_request->which = BAD_WHICH; obj_request->type = type; INIT_LIST_HEAD(&obj_request->links); - atomic_set(&obj_request->done, 0); + obj_request_done_init(obj_request); init_completion(&obj_request->completion); kref_init(&obj_request->kref); @@ -1611,7 +1629,7 @@ static void rbd_img_obj_callback(struct rbd_obj_request *obj_request) rbd_assert(more); rbd_assert(which < img_request->obj_request_count); - if (!atomic_read(&obj_request->done)) + if (!obj_request_done_test(obj_request)) break; rbd_assert(obj_request->xferred <= (u64) UINT_MAX); -- 1.7.9.5