netdev - Re: [PATCH] libertas: Add spinlock to avoid race condition

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Date:	Wed, 15 Jun 2016 18:31:39 +0530
From:	Vaishali Thakkar <vaishali.thakkar@...cle.com>
To:	Pavel Andrianov <andrianov@...ras.ru>,
	Kalle Valo <kvalo@...eaurora.org>
Cc:	libertas-dev@...ts.infradead.org, linux-wireless@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	ldv-project@...uxtesting.org
Subject: Re: [PATCH] libertas: Add spinlock to avoid race condition



On Wednesday 15 June 2016 05:04 PM, Pavel Andrianov wrote:
> lbs_mac_event_disconnected may free priv->currenttxskb
> while lbs_hard_start_xmit accesses to it.
> The patch adds a spinlock for mutual exclusion.
> 
> Tested on OLPC XO-1 (usb8388) and XO-1.5 (sd8686) with v4.7-rc3.
> 
> Confirmed that lbs_mac_event_disconnected is being called on the
> station when hostapd on access point is given SIGHUP.
> 
> Signed-off-by: Pavel <andrianov@...ras.ru>
> Tested-by: James Cameron <quozl@...top.org>

Looks good to me.

Acked-by: Vaishali Thakkar <vaishali.thakkar@...cle.com>

> ---
>  drivers/net/wireless/marvell/libertas/cmdresp.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/wireless/marvell/libertas/cmdresp.c b/drivers/net/wireless/marvell/libertas/cmdresp.c
> index c95bf6d..c67ae07 100644
> --- a/drivers/net/wireless/marvell/libertas/cmdresp.c
> +++ b/drivers/net/wireless/marvell/libertas/cmdresp.c
> @@ -27,6 +27,8 @@
>  void lbs_mac_event_disconnected(struct lbs_private *priv,
>  				bool locally_generated)
>  {
> +	unsigned long flags;
> +
>  	if (priv->connect_status != LBS_CONNECTED)
>  		return;
>  
> @@ -46,9 +48,11 @@ void lbs_mac_event_disconnected(struct lbs_private *priv,
>  	netif_carrier_off(priv->dev);
>  
>  	/* Free Tx and Rx packets */
> +	spin_lock_irqsave(&priv->driver_lock, flags);
>  	kfree_skb(priv->currenttxskb);
>  	priv->currenttxskb = NULL;
>  	priv->tx_pending_len = 0;
> +	spin_unlock_irqrestore(&priv->driver_lock, flags);
>  
>  	priv->connect_status = LBS_DISCONNECTED;
>  
> 

-- 
Vaishali