Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938560AbcLVHUP (ORCPT ); Thu, 22 Dec 2016 02:20:15 -0500 Received: from mx2.suse.de ([195.135.220.15]:48790 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1764275AbcLVHT6 (ORCPT ); Thu, 22 Dec 2016 02:19:58 -0500 From: Juergen Gross To: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org Cc: boris.ostrovsky@oracle.com, Juergen Gross Subject: [PATCH 2/3] xen: return xenstore command failures via response instead of rc Date: Thu, 22 Dec 2016 08:19:47 +0100 Message-Id: <20161222071948.23862-3-jgross@suse.com> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20161222071948.23862-1-jgross@suse.com> References: <20161222071948.23862-1-jgross@suse.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2881 Lines: 99 When the xenbus driver does some special handling for a Xenstore command any error condition related to the command should be returned via an error response instead of letting the related write operation fail. Otherwise the user land handler might take wrong decisions assuming the connection to Xenstore is broken. While at it try to return the same error values xenstored would return for those cases. Signed-off-by: Juergen Gross --- drivers/xen/xenbus/xenbus_dev_frontend.c | 47 ++++++++++++++++++-------------- 1 file changed, 27 insertions(+), 20 deletions(-) diff --git a/drivers/xen/xenbus/xenbus_dev_frontend.c b/drivers/xen/xenbus/xenbus_dev_frontend.c index a068281..79130b3 100644 --- a/drivers/xen/xenbus/xenbus_dev_frontend.c +++ b/drivers/xen/xenbus/xenbus_dev_frontend.c @@ -302,6 +302,29 @@ static void watch_fired(struct xenbus_watch *watch, mutex_unlock(&adap->dev_data->reply_mutex); } +static int xenbus_command_reply(struct xenbus_file_priv *u, + unsigned int msg_type, const char *reply) +{ + struct { + struct xsd_sockmsg hdr; + const char body[16]; + } msg; + int rc; + + msg.hdr = u->u.msg; + msg.hdr.type = msg_type; + msg.hdr.len = strlen(reply) + 1; + if (msg.hdr.len > sizeof(msg.body)) + return -E2BIG; + + mutex_lock(&u->reply_mutex); + rc = queue_reply(&u->read_buffers, &msg, sizeof(msg.hdr) + msg.hdr.len); + wake_up(&u->read_waitq); + mutex_unlock(&u->reply_mutex); + + return rc; +} + static int xenbus_write_transaction(unsigned msg_type, struct xenbus_file_priv *u) { @@ -321,7 +344,7 @@ static int xenbus_write_transaction(unsigned msg_type, if (trans->handle.id == u->u.msg.tx_id) break; if (&trans->list == &u->transactions) - return -ESRCH; + return xenbus_command_reply(u, XS_ERROR, "ENOENT"); } reply = xenbus_dev_request_and_reply(&u->u.msg); @@ -372,12 +395,12 @@ static int xenbus_write_watch(unsigned msg_type, struct xenbus_file_priv *u) path = u->u.buffer + sizeof(u->u.msg); token = memchr(path, 0, u->u.msg.len); if (token == NULL) { - rc = -EILSEQ; + rc = xenbus_command_reply(u, XS_ERROR, "EINVAL"); goto out; } token++; if (memchr(token, 0, u->u.msg.len - (token - path)) == NULL) { - rc = -EILSEQ; + rc = xenbus_command_reply(u, XS_ERROR, "EINVAL"); goto out; } @@ -411,23 +434,7 @@ static int xenbus_write_watch(unsigned msg_type, struct xenbus_file_priv *u) } /* Success. Synthesize a reply to say all is OK. */ - { - struct { - struct xsd_sockmsg hdr; - char body[3]; - } __packed reply = { - { - .type = msg_type, - .len = sizeof(reply.body) - }, - "OK" - }; - - mutex_lock(&u->reply_mutex); - rc = queue_reply(&u->read_buffers, &reply, sizeof(reply)); - wake_up(&u->read_waitq); - mutex_unlock(&u->reply_mutex); - } + rc = xenbus_command_reply(u, msg_type, "OK"); out: return rc; -- 2.10.2