From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756896AbcGZQDD (ORCPT ); Tue, 26 Jul 2016 12:03:03 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:54824 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753112AbcGZQDB (ORCPT ); Tue, 26 Jul 2016 12:03:01 -0400 Subject: Re: [PATCH 1/3] net: ethernet: ti: cpdma: fix lockup in cpdma_ctlr_destroy() To: Ivan Khoronzhuk , "David S. Miller" , , Mugunthan V N References: <20160722135847.20557-1-grygorii.strashko@ti.com> <20160722135847.20557-2-grygorii.strashko@ti.com> CC: Sekhar Nori , , From: Grygorii Strashko Message-ID: <88f436f2-afe9-6a98-5887-95a1d910b57f@ti.com> Date: Tue, 26 Jul 2016 19:02:53 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/23/2016 09:24 AM, Ivan Khoronzhuk wrote: > > > On 22.07.16 16:58, Grygorii Strashko wrote: >> Fix deadlock in cpdma_ctlr_destroy() which is triggered now on >> cpsw module removal: >> cpsw_remove() >> - cpdma_ctlr_destroy() >> - spin_lock_irqsave(&ctlr->lock, flags) >> - cpdma_ctlr_stop() >> - spin_lock_irqsave(&ctlr->lock, flags); <- deadlock >> - cpdma_chan_destroy() >> - spin_lock_irqsave(&ctlr->lock, flags); <- deadlock >> >> The issue has not been observed before because CPDMA channels have >> been destroyed manually by CPSW until commit d941ebe88a41 ("net: >> ethernet: ti: cpsw: use destroy ctlr to destroy channels") was merged. >> >> Signed-off-by: Grygorii Strashko >> --- >> drivers/net/ethernet/ti/davinci_cpdma.c | 2 -- >> 1 file changed, 2 deletions(-) >> >> diff --git a/drivers/net/ethernet/ti/davinci_cpdma.c >> b/drivers/net/ethernet/ti/davinci_cpdma.c >> index a68652a..89242e9 100644 >> --- a/drivers/net/ethernet/ti/davinci_cpdma.c >> +++ b/drivers/net/ethernet/ti/davinci_cpdma.c >> @@ -436,7 +436,6 @@ int cpdma_ctlr_destroy(struct cpdma_ctlr *ctlr) >> if (!ctlr) >> return -EINVAL; >> >> - spin_lock_irqsave(&ctlr->lock, flags); > Should ctlr->state be checked under lock? > Seems like here should be used unlocked static versions of > cpdma_ctlr_stop() and cpdma_chan_destroy() instead. As per my understanding it's not expected the ctlr->state will be changed at this moment as all net devices has been unregistered already. > >> if (ctlr->state != CPDMA_STATE_IDLE) May be I can move above check in cpdma_ctlr_stop() instead. What do you think? >> cpdma_ctlr_stop(ctlr); >> >> @@ -444,7 +443,6 @@ int cpdma_ctlr_destroy(struct cpdma_ctlr *ctlr) >> cpdma_chan_destroy(ctlr->channels[i]); >> >> cpdma_desc_pool_destroy(ctlr->pool); >> - spin_unlock_irqrestore(&ctlr->lock, flags); >> return ret; >> } >> EXPORT_SYMBOL_GPL(cpdma_ctlr_destroy); >> > -- regards, -grygorii