From 522bbe65a2415fabce618186fc7777eb4c502989 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Fri, 3 Sep 2010 12:00:49 -0400 Subject: [PATCH] cifs: prevent cifsd from exiting prematurely When cifs_demultiplex_thread exits, it does a number of cleanup tasks including freeing the TCP_Server_Info struct. Much of the existing code in cifs assumes that when there is a cisfSesInfo struct, that it holds a reference to a valid TCP_Server_Info struct. We can never allow cifsd to exit when a cifsSesInfo struct is still holding a reference to the server. The server pointers will then point to freed memory. This patch eliminates a couple of questionable conditions where it does this. The idea here is to make an -EINTR return from kernel_recvmsg behave the same way as -ERESTARTSYS or -EAGAIN. If the task was signalled from cifs_put_tcp_session, then tcpStatus will be CifsExiting, and the kernel_recvmsg call will return quickly. There's also another condition where this can occur too -- if the tcpStatus is still in CifsNew, then it will also exit if the server closes the socket prematurely. I think we'll probably also need to fix that situation, but that requires a bit more consideration. Signed-off-by: Jeff Layton Signed-off-by: Steve French --- fs/cifs/connect.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 0ea52e9f9065..5f68b968faa7 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -400,7 +400,9 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server) cFYI(1, "call to reconnect done"); csocket = server->ssocket; continue; - } else if ((length == -ERESTARTSYS) || (length == -EAGAIN)) { + } else if (length == -ERESTARTSYS || + length == -EAGAIN || + length == -EINTR) { msleep(1); /* minimum sleep to prevent looping allowing socket to clear and app threads to set tcpStatus CifsNeedReconnect if server hung */ @@ -422,10 +424,6 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server) and so simply return error to mount */ break; } - if (!try_to_freeze() && (length == -EINTR)) { - cFYI(1, "cifsd thread killed"); - break; - } cFYI(1, "Reconnect after unexpected peek error %d", length); cifs_reconnect(server); @@ -522,8 +520,7 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server) total_read += length) { length = kernel_recvmsg(csocket, &smb_msg, &iov, 1, pdu_length - total_read, 0); - if ((server->tcpStatus == CifsExiting) || - (length == -EINTR)) { + if (server->tcpStatus == CifsExiting) { /* then will exit */ reconnect = 2; break; @@ -534,8 +531,9 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server) /* Now we will reread sock */ reconnect = 1; break; - } else if ((length == -ERESTARTSYS) || - (length == -EAGAIN)) { + } else if (length == -ERESTARTSYS || + length == -EAGAIN || + length == -EINTR) { msleep(1); /* minimum sleep to prevent looping, allowing socket to clear and app threads to set tcpStatus -- GitLab