net/ncsi: avoid maybe-uninitialized warning

gcc-4.9 and higher warn about the newly added NSCI code:

net/ncsi/ncsi-manage.c: In function 'ncsi_process_next_channel':
net/ncsi/ncsi-manage.c:1003:2: error: 'old_state' may be used uninitialized in this function [-Werror=maybe-uninitialized]

The warning is a false positive and therefore harmless, but it would be good to
avoid it anyway. I have determined that the barrier in the spin_unlock_irqsave()
is what confuses gcc to the point that it cannot track whether the variable
was unused or not.

This rearranges the code in a way that makes it obvious to gcc that old_state
is always initialized at the time of use, functionally this should not
change anything.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ncsi/ncsi-manage.c b/net/ncsi/ncsi-manage.c
index d627a39ddcd0db6f8f5dd4c99c8b75919ef26151..ef017b871857e3c624040ff5abf37569c94d8b30 100644 (file)
--- a/net/ncsi/ncsi-manage.c
+++ b/net/ncsi/ncsi-manage.c
@@ -982,23 +982,18 @@ int ncsi_process_next_channel(struct ncsi_dev_priv *ndp)
        spin_lock_irqsave(&ndp->lock, flags);
        nc = list_first_or_null_rcu(&ndp->channel_queue,
                                    struct ncsi_channel, link);
-       if (nc) {
-               old_state = xchg(&nc->state, NCSI_CHANNEL_INVISIBLE);
-               list_del_init(&nc->link);
+       if (!nc) {
+               spin_unlock_irqrestore(&ndp->lock, flags);
+               goto out;
        }
+
+       old_state = xchg(&nc->state, NCSI_CHANNEL_INVISIBLE);
+       list_del_init(&nc->link);
+
        spin_unlock_irqrestore(&ndp->lock, flags);
 
        ndp->active_channel = nc;
-       ndp->active_package = nc ? nc->package : NULL;
-       if (!nc) {
-               if (ndp->flags & NCSI_DEV_RESHUFFLE) {
-                       ndp->flags &= ~NCSI_DEV_RESHUFFLE;
-                       return ncsi_choose_active_channel(ndp);
-               }
-
-               ncsi_report_link(ndp, false);
-               return -ENODEV;
-       }
+       ndp->active_package = nc->package;
 
        switch (old_state) {
        case NCSI_CHANNEL_INACTIVE:
@@ -1017,6 +1012,17 @@ int ncsi_process_next_channel(struct ncsi_dev_priv *ndp)
        }
 
        return 0;
+
+out:
+       ndp->active_channel = NULL;
+       ndp->active_package = NULL;
+       if (ndp->flags & NCSI_DEV_RESHUFFLE) {
+               ndp->flags &= ~NCSI_DEV_RESHUFFLE;
+               return ncsi_choose_active_channel(ndp);
+       }
+
+       ncsi_report_link(ndp, false);
+       return -ENODEV;
 }
 
 #if IS_ENABLED(CONFIG_IPV6)