From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756019AbdCTSrU (ORCPT ); Mon, 20 Mar 2017 14:47:20 -0400 Received: from foss.arm.com ([217.140.101.70]:44440 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755240AbdCTSrT (ORCPT ); Mon, 20 Mar 2017 14:47:19 -0400 Date: Mon, 20 Mar 2017 18:47:14 +0000 From: Alexey Klimov To: Sudeep Holla Cc: linux-kernel@vger.kernel.org, Jassi Brar , Jassi Brar Subject: Re: [PATCH] mailbox: always wait in mbox_send_message for blocking tx mode Message-ID: <20170320184714.GB32325@arm.com> References: <1490024410-10287-1-git-send-email-sudeep.holla@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1490024410-10287-1-git-send-email-sudeep.holla@arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sudeep, thanks for sending this patch. On Mon, Mar 20, 2017 at 03:40:10PM +0000, Sudeep Holla wrote: > There exists a race when msg_submit return immediately as there was an > active request being processed which may have completed just before it's > checked again in mbox_send_message. This will result in return to the > caller without waiting in mbox_send_message even when it's blocking Tx. > > This patch fixes the issue by making use of non-negative token returned > by add_to_rbuf to check if the request was queued and block always if > so in blocking Tx mode. > > Fixes: 2b6d83e2b8b7 ("mailbox: Introduce framework for mailbox") > Cc: Jassi Brar > Reported-by: Alexey Klimov > Signed-off-by: Sudeep Holla > --- > drivers/mailbox/mailbox.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c > index 4671f8a12872..d5895791ab5d 100644 > --- a/drivers/mailbox/mailbox.c > +++ b/drivers/mailbox/mailbox.c > @@ -260,7 +260,7 @@ int mbox_send_message(struct mbox_chan *chan, void *mssg) > > msg_submit(chan); > > - if (chan->cl->tx_block && chan->active_req) { > + if (chan->cl->tx_block && t >= 0) { What do you think about removing t>=0 at all? If add_to_rbuf() above returns negative number then we won't reach this point in code at all and quit this function with error. If execution reaches this line then we can say that t is definetely >= 0 and maybe it shouldn't be checked. Best regards, Alexey