4.4-stable review patch. If anyone has any objections, please let me know.
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From: Paulo Alcantara paulo@paulo.ac
commit 7ffbe65578b44fafdef577a360eb0583929f7c6e upstream.
For every request we send, whether it is SMB1 or SMB2+, we attempt to reconnect tcon (cifs_reconnect_tcon or smb2_reconnect) before carrying out the request.
So, while server->tcpStatus != CifsNeedReconnect, we wait for the reconnection to succeed on wait_event_interruptible_timeout(). If it returns, that means that either the condition was evaluated to true, or timeout elapsed, or it was interrupted by a signal.
Since we're not handling the case where the process woke up due to a received signal (-ERESTARTSYS), the next call to wait_event_interruptible_timeout() will _always_ fail and we end up looping forever inside either cifs_reconnect_tcon() or smb2_reconnect().
Here's an example of how to trigger that:
$ mount.cifs //foo/share /mnt/test -o username=foo,password=foo,vers=1.0,hard
(break connection to server before executing bellow cmd) $ stat -f /mnt/test & sleep 140 [1] 2511
$ ps -aux -q 2511 USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 2511 0.0 0.0 12892 1008 pts/0 S 12:24 0:00 stat -f /mnt/test
$ kill -9 2511
(wait for a while; process is stuck in the kernel) $ ps -aux -q 2511 USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 2511 83.2 0.0 12892 1008 pts/0 R 12:24 30:01 stat -f /mnt/test
By using 'hard' mount point means that cifs.ko will keep retrying indefinitely, however we must allow the process to be killed otherwise it would hang the system.
Signed-off-by: Paulo Alcantara palcantara@suse.de Cc: stable@vger.kernel.org Reviewed-by: Aurelien Aptel aaptel@suse.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/cifs/cifssmb.c | 10 ++++++++-- fs/cifs/smb2pdu.c | 18 ++++++++++++------ 2 files changed, 20 insertions(+), 8 deletions(-)
--- a/fs/cifs/cifssmb.c +++ b/fs/cifs/cifssmb.c @@ -150,8 +150,14 @@ cifs_reconnect_tcon(struct cifs_tcon *tc * greater than cifs socket timeout which is 7 seconds */ while (server->tcpStatus == CifsNeedReconnect) { - wait_event_interruptible_timeout(server->response_q, - (server->tcpStatus != CifsNeedReconnect), 10 * HZ); + rc = wait_event_interruptible_timeout(server->response_q, + (server->tcpStatus != CifsNeedReconnect), + 10 * HZ); + if (rc < 0) { + cifs_dbg(FYI, "%s: aborting reconnect due to a received" + " signal by the process\n", __func__); + return -ERESTARTSYS; + }
/* are we still trying to reconnect? */ if (server->tcpStatus != CifsNeedReconnect) --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -158,7 +158,7 @@ out: static int smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon) { - int rc = 0; + int rc; struct nls_table *nls_codepage; struct cifs_ses *ses; struct TCP_Server_Info *server; @@ -169,10 +169,10 @@ smb2_reconnect(__le16 smb2_command, stru * for those three - in the calling routine. */ if (tcon == NULL) - return rc; + return 0;
if (smb2_command == SMB2_TREE_CONNECT) - return rc; + return 0;
if (tcon->tidStatus == CifsExiting) { /* @@ -215,8 +215,14 @@ smb2_reconnect(__le16 smb2_command, stru return -EAGAIN; }
- wait_event_interruptible_timeout(server->response_q, - (server->tcpStatus != CifsNeedReconnect), 10 * HZ); + rc = wait_event_interruptible_timeout(server->response_q, + (server->tcpStatus != CifsNeedReconnect), + 10 * HZ); + if (rc < 0) { + cifs_dbg(FYI, "%s: aborting reconnect due to a received" + " signal by the process\n", __func__); + return -ERESTARTSYS; + }
/* are we still trying to reconnect? */ if (server->tcpStatus != CifsNeedReconnect) @@ -234,7 +240,7 @@ smb2_reconnect(__le16 smb2_command, stru }
if (!tcon->ses->need_reconnect && !tcon->need_reconnect) - return rc; + return 0;
nls_codepage = load_nls_default();