* Re: [BUG] znet.c sleeping function called from invalid context
2009-10-07 18:44 ` Mike Frysinger
@ 2009-10-08 5:15 ` David Miller
0 siblings, 0 replies; 3+ messages in thread
From: David Miller @ 2009-10-08 5:15 UTC (permalink / raw)
To: vapier.adi
Cc: michael.hennerich, netdev, linux-kernel, strakh, uclinux-dist-devel
From: Mike Frysinger <vapier.adi@gmail.com>
Date: Wed, 7 Oct 2009 14:44:45 -0400
> On Wed, Oct 7, 2009 at 14:47, Alexander Strakh wrote:
>> KERNEL_VERSION: 2.6.31
>> DESCRIBE:
>> Driver drivers/net/znet.c might sleep in atomic context, because it calls
>> free_dma under claim_dma_lock:
>>
>> .drivers/net/znet.c:
>> 168 static int znet_request_resources (struct net_device *dev)
>> ...
>> 189 flags = claim_dma_lock();
>> 190 free_dma (znet->tx_dma);
>> 191 release_dma_lock (flags);
>> ...
>>
>> Path to might_sleep macro from znet_request_resources:
>> 1. znet_request_resources calls free_dma at
>> arch/blackfin/kernel/bfin_dma_5xx.c:181
>> 2. free_dma calls arch/blackfin/kernel/bfin_dma_5xx.c:195
>
> i dont think we need the dmalock mutex. it's only used to protect
> read/writes to .chan_status, and that should be atomic already.
> -mike
I'm checking in the obvious fix to net-2.6, thanks for the report:
znet: Don't claim DMA lock around free_dma() calls.
It's not necessary and it's illegal too.
Reported-by: Alexander Strakh <strakh@ispras.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
drivers/net/znet.c | 8 --------
1 files changed, 0 insertions(+), 8 deletions(-)
diff --git a/drivers/net/znet.c b/drivers/net/znet.c
index a0384b6..b423473 100644
--- a/drivers/net/znet.c
+++ b/drivers/net/znet.c
@@ -169,7 +169,6 @@ static void znet_tx_timeout (struct net_device *dev);
static int znet_request_resources (struct net_device *dev)
{
struct znet_private *znet = netdev_priv(dev);
- unsigned long flags;
if (request_irq (dev->irq, &znet_interrupt, 0, "ZNet", dev))
goto failed;
@@ -187,13 +186,9 @@ static int znet_request_resources (struct net_device *dev)
free_sia:
release_region (znet->sia_base, znet->sia_size);
free_tx_dma:
- flags = claim_dma_lock();
free_dma (znet->tx_dma);
- release_dma_lock (flags);
free_rx_dma:
- flags = claim_dma_lock();
free_dma (znet->rx_dma);
- release_dma_lock (flags);
free_irq:
free_irq (dev->irq, dev);
failed:
@@ -203,14 +198,11 @@ static int znet_request_resources (struct net_device *dev)
static void znet_release_resources (struct net_device *dev)
{
struct znet_private *znet = netdev_priv(dev);
- unsigned long flags;
release_region (znet->sia_base, znet->sia_size);
release_region (dev->base_addr, znet->io_size);
- flags = claim_dma_lock();
free_dma (znet->tx_dma);
free_dma (znet->rx_dma);
- release_dma_lock (flags);
free_irq (dev->irq, dev);
}
--
1.6.4.4
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