From 9a6161fe73bdd3ae4a1e18421b0b20cb7141f680 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 22 Dec 2016 08:19:47 +0100 Subject: [PATCH] xen: return xenstore command failures via response instead of rc 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 Reviewed-by: Boris Ostrovsky 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 a06828124b70..79130b310247 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;