cifs: avoid parallel session setups on same channel

After allowing channels to reconnect in parallel, it now
becomes important to take care that multiple processes do not
call negotiate/session setup in parallel on the same channel.

This change avoids that by marking a channel as "in_reconnect".
During session setup if the channel in question has this flag
set, we return immediately.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 20 insertions, 7 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index df4bcc581559..199b076f7a64 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3995,17 +3995,27 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
 	int rc = -ENOSYS;
 	bool is_binding = false;
 
-	/* only send once per connect */
-	spin_lock(&ses->chan_lock);
-	is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);
-	spin_unlock(&ses->chan_lock);
 
 	spin_lock(&cifs_tcp_ses_lock);
-	if (ses->ses_status == SES_EXITING) {
+	if (ses->ses_status != SES_GOOD &&
+	    ses->ses_status != SES_NEW &&
+	    ses->ses_status != SES_NEED_RECON) {
 		spin_unlock(&cifs_tcp_ses_lock);
 		return 0;
 	}
 
+	/* only send once per connect */
+	spin_lock(&ses->chan_lock);
+	if (CIFS_ALL_CHANS_GOOD(ses) ||
+	    cifs_chan_in_reconnect(ses, server)) {
+		spin_unlock(&ses->chan_lock);
+		spin_unlock(&cifs_tcp_ses_lock);
+		return 0;
+	}
+	is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);
+	cifs_chan_set_in_reconnect(ses, server);
+	spin_unlock(&ses->chan_lock);
+
 	if (!is_binding)
 		ses->ses_status = SES_IN_SETUP;
 	spin_unlock(&cifs_tcp_ses_lock);
@@ -4035,16 +4045,19 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
 		spin_lock(&cifs_tcp_ses_lock);
 		if (ses->ses_status == SES_IN_SETUP)
 			ses->ses_status = SES_NEED_RECON;
+		spin_lock(&ses->chan_lock);
+		cifs_chan_clear_in_reconnect(ses, server);
+		spin_unlock(&ses->chan_lock);
 		spin_unlock(&cifs_tcp_ses_lock);
 	} else {
 		spin_lock(&cifs_tcp_ses_lock);
 		if (ses->ses_status == SES_IN_SETUP)
 			ses->ses_status = SES_GOOD;
-		spin_unlock(&cifs_tcp_ses_lock);
-
 		spin_lock(&ses->chan_lock);
+		cifs_chan_clear_in_reconnect(ses, server);
 		cifs_chan_clear_need_reconnect(ses, server);
 		spin_unlock(&ses->chan_lock);
+		spin_unlock(&cifs_tcp_ses_lock);
 	}
 
 	return rc;