[PATCH v2] net/libertas: don't recursive spin lock in if_spi_e2h()

[Dan Williams]

On Fri, 2009-06-12 at 21:37 +0200, Sebastian Andrzej Siewior wrote:
> |BUG: spinlock recursion on CPU#0, lbs_spi_thread/1030
> | lock: dee9a1bc, .magic: dead4ead, .owner: lbs_spi_thread/1030, .owner_cpu: 0
> |Call Trace:
> |[deec3eb0] [c0007220] show_stack+0x4c/0x15c (unreliable)
> |[deec3ef0] [c0187720] spin_bug+0x9c/0xb0
> |[deec3f10] [c0187890] _raw_spin_lock+0x54/0x148
> |[deec3f40] [c02d260c] _spin_lock_irqsave+0x2c/0x44
> |[deec3f60] [e8671800] lbs_queue_event+0x7c/0x130 [libertas]
> |[deec3f80] [e8725f04] lbs_spi_thread+0x538/0x58c [libertas_spi]
> |[deec3fe0] [c004f270] kthread+0x4c/0x88
> |[deec3ff0] [c000f33c] kernel_thread+0x4c/0x68
> 
> if_spi_e2h() is grabbing ->driver_lock just while calling
> lbs_queue_event() which is grabbing the same lock.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy at linutronix.de>

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

> ---
> v1..v2: remove flags
> 
>  drivers/net/wireless/libertas/if_spi.c |    4 ----
>  1 files changed, 0 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/wireless/libertas/if_spi.c b/drivers/net/wireless/libertas/if_spi.c
> index f8c2898..583162c 100644
> --- a/drivers/net/wireless/libertas/if_spi.c
> +++ b/drivers/net/wireless/libertas/if_spi.c
> @@ -812,7 +812,6 @@ out:
>  static void if_spi_e2h(struct if_spi_card *card)
>  {
>  	int err = 0;
> -	unsigned long flags;
>  	u32 cause;
>  	struct lbs_private *priv = card->priv;
>  
> @@ -827,10 +826,7 @@ static void if_spi_e2h(struct if_spi_card *card)
>  	/* generate a card interrupt */
>  	spu_write_u16(card, IF_SPI_CARD_INT_CAUSE_REG, IF_SPI_CIC_HOST_EVENT);
>  
> -	spin_lock_irqsave(&priv->driver_lock, flags);
>  	lbs_queue_event(priv, cause & 0xff);
> -	spin_unlock_irqrestore(&priv->driver_lock, flags);
> -
>  out:
>  	if (err)
>  		lbs_pr_err("%s: error %d\n", __func__, err);