From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752551AbaKLJmC (ORCPT ); Wed, 12 Nov 2014 04:42:02 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59296 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752361AbaKLJlU (ORCPT ); Wed, 12 Nov 2014 04:41:20 -0500 From: Vitaly Kuznetsov To: Dexuan Cui Cc: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, driverdev-devel@linuxdriverproject.org, olaf@aepfle.de, apw@canonical.com, jasowang@redhat.com, kys@microsoft.com, haiyangz@microsoft.com Subject: Re: [PATCH] hv: hv_fcopy: drop the obsolete message on transfer failure References: <1415768606-28538-1-git-send-email-decui@microsoft.com> Date: Wed, 12 Nov 2014 10:41:03 +0100 In-Reply-To: <1415768606-28538-1-git-send-email-decui@microsoft.com> (Dexuan Cui's message of "Tue, 11 Nov 2014 21:03:26 -0800") Message-ID: <87oasc69jk.fsf@vitty.brq.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dexuan Cui writes: > In the case the user-space daemon crashes, hangs or is killed, we > need to down the semaphore, otherwise, after the daemon starts next > time, the obsolete data in fcopy_transaction.message or > fcopy_transaction.fcopy_msg will be used immediately. > > Cc: K. Y. Srinivasan > Signed-off-by: Dexuan Cui Reviewed-by: Vitaly Kuznetsov > --- > drivers/hv/hv_fcopy.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/hv/hv_fcopy.c b/drivers/hv/hv_fcopy.c > index 23b2ce2..177122a 100644 > --- a/drivers/hv/hv_fcopy.c > +++ b/drivers/hv/hv_fcopy.c > @@ -86,6 +86,15 @@ static void fcopy_work_func(struct work_struct *dummy) > * process the pending transaction. > */ > fcopy_respond_to_host(HV_E_FAIL); > + > + /* In the case the user-space daemon crashes, hangs or is killed, we > + * need to down the semaphore, otherwise, after the daemon starts next > + * time, the obsolete data in fcopy_transaction.message or > + * fcopy_transaction.fcopy_msg will be used immediately. > + */ > + if (down_trylock(&fcopy_transaction.read_sema)) > + pr_debug("FCP: failed to acquire the semaphore\n"); > + > } > > static int fcopy_handle_handshake(u32 version) -- Vitaly