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: Stanislav Yakovlev <stas.yakovlev@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/drivers/net/wireless/ipw2x00/ipw2200.c b/drivers/net/wireless/ipw2x00/ipw2200.c
index 2b022571a859..1779db3aa2b0 100644
--- a/drivers/net/wireless/ipw2x00/ipw2200.c
+++ b/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) {