[ 67/75] ipw2200: Fix race condition in the command completion acknowledge

Greg KH
2012-05-04T21:06:31Z

From: Stanislav Yakovlev <stas.yakovlev@gmail.com>

commit dd447319895d0c0af423e483d9b63f84f3f8869a upstream.

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.

Signed-off-by: Stanislav Yakovlev <stas.yakovlev@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/wireless/ipw2x00/ipw2200.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

--- 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_pri
{
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_pri
}
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) {