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Wed, 30 Sep 2020 18:31:38 +0000 Date: Wed, 30 Sep 2020 15:31:36 -0300 From: Jason Gunthorpe To: Leon Romanovsky CC: Doug Ledford , Dan Aloni , Subject: Re: [PATCH rdma-next] RDMA/addr: Fix race with netevent_callback()/rdma_addr_cancel() Message-ID: <20200930183136.GA1031970@nvidia.com> References: <20200930072007.1009692-1-leon@kernel.org> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20200930072007.1009692-1-leon@kernel.org> X-ClientProxiedBy: MN2PR20CA0050.namprd20.prod.outlook.com (2603:10b6:208:235::19) To DM6PR12MB3834.namprd12.prod.outlook.com (2603:10b6:5:14a::12) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from mlx.ziepe.ca (156.34.48.30) by MN2PR20CA0050.namprd20.prod.outlook.com (2603:10b6:208:235::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3433.32 via Frontend Transport; Wed, 30 Sep 2020 18:31:37 +0000 Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kNgt6-004KTf-Iv; Wed, 30 Sep 2020 15:31:36 -0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1601490597; bh=aB2nvRdtDK8IaIifUGstgSGDWJX0GKZ02H7z/AWtzKI=; h=ARC-Seal:ARC-Message-Signature:ARC-Authentication-Results:Date: From:To:CC:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:X-ClientProxiedBy:MIME-Version: X-MS-Exchange-MessageSentRepresentingType; b=gHTN+vZBqNlaz4TPu1EuZrWOyzjKF8GnutYRQI3jC0H2JEjwBJ/OBYOK6JTnZbWnc 9NT2gIzE2HmFtIonl6xdD8XZ5PIpYBOuqYGRjc3jGbZj5cT5LBLf4Ml6Hc0XckPEoS 9poZn2bqbReYTLzBAzISNzLeejSM+oeCLHtnVfbJZt9UbZx93Fr7c2WDR1ML86IObm 2FzS9TQ8L0/VcPeW/gREOEqGxTcRAWGnCityxtY/Tx9kjQc5dWNGdIr0930ZMUxG/5 K9TmavdJoCsrF7K11BZYsBJbxlMJVYZbhXX1FUDQ14NwQmwsyU5EPmE5B3Bm9x4PgO HWnfB+Sel8o5w== Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Wed, Sep 30, 2020 at 10:20:07AM +0300, Leon Romanovsky wrote: > From: Jason Gunthorpe > > This three thread race can result in the work being run once the callback > becomes NULL: > > CPU1 CPU2 CPU3 > netevent_callback() > process_one_req() rdma_addr_cancel() > [..] > spin_lock_bh() > set_timeout() > spin_unlock_bh() > > spin_lock_bh() > list_del_init(&req->list); > spin_unlock_bh() > > req->callback = NULL > spin_lock_bh() > if (!list_empty(&req->list)) > // Skipped! > // cancel_delayed_work(&req->work); > spin_unlock_bh() > > process_one_req() // again > req->callback() // BOOM > cancel_delayed_work_sync() > > The solution is to always cancel the work once it is completed so any > in between set_timeout() does not result in it running again. > > Fixes: 44e75052bc2a ("RDMA/rdma_cm: Make rdma_addr_cancel into a fence") > Reported-by: Dan Aloni > Signed-off-by: Jason Gunthorpe > Signed-off-by: Leon Romanovsky > --- > drivers/infiniband/core/addr.c | 11 +++++------ > 1 file changed, 5 insertions(+), 6 deletions(-) Applied to for-next Jason