net/ncsi: Avoid unused-value build warning from ia64-linux-gcc

xchg() is used to set NCSI channel's state in order for consistent
access to the state. xchg()'s return value should be used. Otherwise,
one build warning will be raised (with -Wunused-value) as below message
indicates. It is reported by ia64-linux-gcc (GCC) 4.9.0.

 net/ncsi/ncsi-manage.c: In function 'ncsi_channel_monitor':
 arch/ia64/include/uapi/asm/cmpxchg.h:56:2: warning: value computed is \
 not used [-Wunused-value]
  ((__typeof__(*(ptr))) __xchg((unsigned long) (x), (ptr), sizeof(*(ptr))))
   ^
 net/ncsi/ncsi-manage.c:202:3: note: in expansion of macro 'xchg'
  xchg(&nc->state, NCSI_CHANNEL_INACTIVE);

This removes the atomic access to NCSI channel's state avoid the above
build warning. We have to hold the channel's lock when its state is readed
or updated. No functional changes introduced.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 27 insertions, 10 deletions

diff --git a/net/ncsi/ncsi-aen.c b/net/ncsi/ncsi-aen.c
index d463468442ae..b41a6617d498 100644
--- a/net/ncsi/ncsi-aen.c
+++ b/net/ncsi/ncsi-aen.c
@@ -53,7 +53,9 @@ static int ncsi_aen_handler_lsc(struct ncsi_dev_priv *ndp,
 	struct ncsi_aen_lsc_pkt *lsc;
 	struct ncsi_channel *nc;
 	struct ncsi_channel_mode *ncm;
-	unsigned long old_data;
+	bool chained;
+	int state;
+	unsigned long old_data, data;
 	unsigned long flags;
 
 	/* Find the NCSI channel */
@@ -62,20 +64,27 @@ static int ncsi_aen_handler_lsc(struct ncsi_dev_priv *ndp,
 		return -ENODEV;
 
 	/* Update the link status */
-	ncm = &nc->modes[NCSI_MODE_LINK];
 	lsc = (struct ncsi_aen_lsc_pkt *)h;
+
+	spin_lock_irqsave(&nc->lock, flags);
+	ncm = &nc->modes[NCSI_MODE_LINK];
 	old_data = ncm->data[2];
-	ncm->data[2] = ntohl(lsc->status);
+	data = ntohl(lsc->status);
+	ncm->data[2] = data;
 	ncm->data[4] = ntohl(lsc->oem_status);
-	if (!((old_data ^ ncm->data[2]) & 0x1) ||
-	    !list_empty(&nc->link))
+
+	chained = !list_empty(&nc->link);
+	state = nc->state;
+	spin_unlock_irqrestore(&nc->lock, flags);
+
+	if (!((old_data ^ data) & 0x1) || chained)
 		return 0;
-	if (!(nc->state == NCSI_CHANNEL_INACTIVE && (ncm->data[2] & 0x1)) &&
-	    !(nc->state == NCSI_CHANNEL_ACTIVE && !(ncm->data[2] & 0x1)))
+	if (!(state == NCSI_CHANNEL_INACTIVE && (data & 0x1)) &&
+	    !(state == NCSI_CHANNEL_ACTIVE && !(data & 0x1)))
 		return 0;
 
 	if (!(ndp->flags & NCSI_DEV_HWA) &&
-	    nc->state == NCSI_CHANNEL_ACTIVE)
+	    state == NCSI_CHANNEL_ACTIVE)
 		ndp->flags |= NCSI_DEV_RESHUFFLE;
 
 	ncsi_stop_channel_monitor(nc);
@@ -97,13 +106,21 @@ static int ncsi_aen_handler_cr(struct ncsi_dev_priv *ndp,
 	if (!nc)
 		return -ENODEV;
 
+	spin_lock_irqsave(&nc->lock, flags);
 	if (!list_empty(&nc->link) ||
-	    nc->state != NCSI_CHANNEL_ACTIVE)
+	    nc->state != NCSI_CHANNEL_ACTIVE) {
+		spin_unlock_irqrestore(&nc->lock, flags);
 		return 0;
+	}
+	spin_unlock_irqrestore(&nc->lock, flags);
 
 	ncsi_stop_channel_monitor(nc);
+	spin_lock_irqsave(&nc->lock, flags);
+	nc->state = NCSI_CHANNEL_INVISIBLE;
+	spin_unlock_irqrestore(&nc->lock, flags);
+
 	spin_lock_irqsave(&ndp->lock, flags);
-	xchg(&nc->state, NCSI_CHANNEL_INACTIVE);
+	nc->state = NCSI_CHANNEL_INACTIVE;
 	list_add_tail_rcu(&nc->link, &ndp->channel_queue);
 	spin_unlock_irqrestore(&ndp->lock, flags);