cifs: add missing spinlock around tcon refcount

Add missing spinlock to protect updates on tcon refcount in
cifs_put_tcon().

Fixes: d7d7a66aacd6 ("cifs: avoid use of global locks for high contention data")
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 0225f4c..7ae6f2c 100644 (file)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2345,7 +2345,9 @@ cifs_put_tcon(struct cifs_tcon *tcon)
        ses = tcon->ses;
        cifs_dbg(FYI, "%s: tc_count=%d\n", __func__, tcon->tc_count);
        spin_lock(&cifs_tcp_ses_lock);
+       spin_lock(&tcon->tc_lock);
        if (--tcon->tc_count > 0) {
+               spin_unlock(&tcon->tc_lock);
                spin_unlock(&cifs_tcp_ses_lock);
                return;
        }
@@ -2354,6 +2356,7 @@ cifs_put_tcon(struct cifs_tcon *tcon)
        WARN_ON(tcon->tc_count < 0);
 
        list_del_init(&tcon->tcon_list);
+       spin_unlock(&tcon->tc_lock);
        spin_unlock(&cifs_tcp_ses_lock);
 
        /* cancel polling of interfaces */