[PATCH] libertas: fix cmdpendingq locking

[Dan Williams]

On Mon, 2011-05-09 at 10:40 +0100, Daniel Drake wrote:
> From: Paul Fox <pgf at laptop.org>
> 
> We occasionally see list corruption using libertas.
> 
> While we haven't been able to diagnose this precisely, we have spotted
> a possible cause: cmdpendingq is generally modified with driver_lock
> held. However, there are a couple of points where this is not the case.
> 
> Fix up those operations to execute under the lock, it seems like
> the correct thing to do and will hopefully improve the situation.
> 
> Signed-off-by: Paul Fox <pgf at laptop.org>
> Signed-off-by: Daniel Drake <dsd at laptop.org>

Acked-by: Dan Williams <dcbw at redhat.com>

Also a candidate for stable@?

> ---
>  drivers/net/wireless/libertas/cmd.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/libertas/cmd.c b/drivers/net/wireless/libertas/cmd.c
> index 7e8a658..f3ac624 100644
> --- a/drivers/net/wireless/libertas/cmd.c
> +++ b/drivers/net/wireless/libertas/cmd.c
> @@ -1339,8 +1339,8 @@ int lbs_execute_next_command(struct lbs_private *priv)
>  				    cpu_to_le16(PS_MODE_ACTION_EXIT_PS)) {
>  					lbs_deb_host(
>  					       "EXEC_NEXT_CMD: ignore ENTER_PS cmd\n");
> -					list_del(&cmdnode->list);
>  					spin_lock_irqsave(&priv->driver_lock, flags);
> +					list_del(&cmdnode->list);
>  					lbs_complete_command(priv, cmdnode, 0);
>  					spin_unlock_irqrestore(&priv->driver_lock, flags);
>  
> @@ -1352,8 +1352,8 @@ int lbs_execute_next_command(struct lbs_private *priv)
>  				    (priv->psstate == PS_STATE_PRE_SLEEP)) {
>  					lbs_deb_host(
>  					       "EXEC_NEXT_CMD: ignore EXIT_PS cmd in sleep\n");
> -					list_del(&cmdnode->list);
>  					spin_lock_irqsave(&priv->driver_lock, flags);
> +					list_del(&cmdnode->list);
>  					lbs_complete_command(priv, cmdnode, 0);
>  					spin_unlock_irqrestore(&priv->driver_lock, flags);
>  					priv->needtowakeup = 1;
> @@ -1366,7 +1366,9 @@ int lbs_execute_next_command(struct lbs_private *priv)
>  				       "EXEC_NEXT_CMD: sending EXIT_PS\n");
>  			}
>  		}
> +		spin_lock_irqsave(&priv->driver_lock, flags);
>  		list_del(&cmdnode->list);
> +		spin_unlock_irqrestore(&priv->driver_lock, flags);
>  		lbs_deb_host("EXEC_NEXT_CMD: sending command 0x%04x\n",
>  			    le16_to_cpu(cmd->command));
>  		lbs_submit_command(priv, cmdnode);