ipw2200: Fix race condition in the command completion acknowledge

Driver incorrectly validates command completion: instead of waiting
for a command to be acknowledged it continues execution.  Most of the
time driver gets acknowledge of the command completion in a tasklet
before it executes the next one. But sometimes it sends the next
command before it gets acknowledge for the previous one. In such a
case one of the following error messages appear in the log:

Failed to send SYSTEM_CONFIG: Already sending a command.
Failed to send ASSOCIATE: Already sending a command.
Failed to send TX_POWER: Already sending a command.

After that you need to reload the driver to get it working again.

This bug occurs during roaming (reported by Sam Varshavchik)
https://bugzilla.redhat.com/show_bug.cgi?id=738508
and machine booting (reported by Tom Gundersen and Mads Kiilerich)
https://bugs.archlinux.org/task/28097
https://bugzilla.redhat.com/show_bug.cgi?id=802106

This patch doesn't fix the delay issue during firmware load.
But at least device now works as usual after boot.

Cc: stable@kernel.org
Signed-off-by: NStanislav Yakovlev <stas.yakovlev@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ipw2x00/ipw2200.c

@@ -2191,6 +2191,7 @@ static int __ipw_send_cmd(struct ipw_priv *priv, struct host_cmd *cmd)
 {
 	int rc = 0;
 	unsigned long flags;
+	unsigned long now, end;
 
 	spin_lock_irqsave(&priv->lock, flags);
 	if (priv->status & STATUS_HCMD_ACTIVE) {
@@ -2232,10 +2233,20 @@ static int __ipw_send_cmd(struct ipw_priv *priv, struct host_cmd *cmd)
 	}
 	spin_unlock_irqrestore(&priv->lock, flags);
 
+	now = jiffies;
+	end = now + HOST_COMPLETE_TIMEOUT;
+again:
 	rc = wait_event_interruptible_timeout(priv->wait_command_queue,
 					      !(priv->
 						status & STATUS_HCMD_ACTIVE),
-					      HOST_COMPLETE_TIMEOUT);
+					      end - now);
+	if (rc < 0) {
+		now = jiffies;
+		if (time_before(now, end))
+			goto again;
+		rc = 0;
+	}
+
 	if (rc == 0) {
 		spin_lock_irqsave(&priv->lock, flags);
 		if (priv->status & STATUS_HCMD_ACTIVE) {