From e691b9d1a096fbaaff9d6d6aef1adc593b786e62 Mon Sep 17 00:00:00 2001 From: Steve French Date: Sun, 11 May 2008 15:53:33 +0000 Subject: [CIFS] don't allow demultiplex thread to exit until kthread_stop is called cifs_demultiplex_thread can exit under several conditions: 1) if it's signaled 2) if there's a problem with session setup 3) if kthread_stop is called on it The first two are problems. If kthread_stop is called on the thread, there is no guarantee that it will still be up. We need to have the thread stay up until kthread_stop is called on it. One option would be to not even try to tear things down until after kthread_stop is called. However, in the case where there is a problem setting up the session, there's no real reason to try continuing the loop. This patch allows the thread to clean up and prepare for exit under all three conditions, but it has the thread go to sleep until kthread_stop is called. This allows us to simplify the shutdown code somewhat since we can be reasonably sure that the thread won't exit after being signaled but before kthread_stop is called. It also removes the places where the thread itself set the tsk variable since it appeared that it could have a potential race where the thread might never be shut down. Signed-off-by: Jeff Layton Acked-by: Christoph Hellwig Signed-off-by: Steve French --- fs/cifs/connect.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) (limited to 'fs') diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 965050867599..f428bf3bf1a9 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -348,7 +348,6 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server) int reconnect; current->flags |= PF_MEMALLOC; - server->tsk = current; /* save process info to wake at shutdown */ cFYI(1, ("Demultiplex PID: %d", task_pid_nr(current))); write_lock(&GlobalSMBSeslock); atomic_inc(&tcpSesAllocCount); @@ -651,10 +650,20 @@ multi_t2_fnd: spin_lock(&GlobalMid_Lock); server->tcpStatus = CifsExiting; - server->tsk = NULL; + spin_unlock(&GlobalMid_Lock); + + /* don't exit until kthread_stop is called */ + set_current_state(TASK_UNINTERRUPTIBLE); + while (!kthread_should_stop()) { + schedule(); + set_current_state(TASK_UNINTERRUPTIBLE); + } + set_current_state(TASK_RUNNING); + /* check if we have blocked requests that need to free */ /* Note that cifs_max_pending is normally 50, but can be set at module install time to as little as two */ + spin_lock(&GlobalMid_Lock); if (atomic_read(&server->inFlight) >= cifs_max_pending) atomic_set(&server->inFlight, cifs_max_pending - 1); /* We do not want to set the max_pending too low or we @@ -2187,15 +2196,12 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, srvTcp->tcpStatus = CifsExiting; spin_unlock(&GlobalMid_Lock); if (srvTcp->tsk) { - struct task_struct *tsk; /* If we could verify that kthread_stop would always wake up processes blocked in tcp in recv_mesg then we could remove the send_sig call */ force_sig(SIGKILL, srvTcp->tsk); - tsk = srvTcp->tsk; - if (tsk) - kthread_stop(tsk); + kthread_stop(srvTcp->tsk); } } /* If find_unc succeeded then rc == 0 so we can not end */ @@ -2211,23 +2217,17 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, if ((temp_rc == -ESHUTDOWN) && (pSesInfo->server) && (pSesInfo->server->tsk)) { - struct task_struct *tsk; force_sig(SIGKILL, pSesInfo->server->tsk); - tsk = pSesInfo->server->tsk; - if (tsk) - kthread_stop(tsk); + kthread_stop(pSesInfo->server->tsk); } } else { cFYI(1, ("No session or bad tcon")); if ((pSesInfo->server) && (pSesInfo->server->tsk)) { - struct task_struct *tsk; force_sig(SIGKILL, pSesInfo->server->tsk); - tsk = pSesInfo->server->tsk; - if (tsk) - kthread_stop(tsk); + kthread_stop(pSesInfo->server->tsk); } } sesInfoFree(pSesInfo); -- cgit v1.2.2