Patchwork tg3: fix tigon3_dma_hwbug_workaround()

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Submitter Eric Dumazet
Date Oct. 22, 2011, 7:25 a.m.
Message ID <1319268338.6180.20.camel@edumazet-laptop>
Download mbox | patch
Permalink /patch/121160/
State Accepted
Delegated to: David Miller
Headers show

Comments

Eric Dumazet - Oct. 22, 2011, 7:25 a.m.
Ari got kernel panics using tg3 NIC, and bisected to 2669069aacc9 "tg3:
enable transmit time stamping."

This is because tigon3_dma_hwbug_workaround() might alloc a new skb and
free the original. We panic when skb_tx_timestamp() is called on freed
skb.

Reported-by: Ari Savolainen <ari.m.savolainen@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
---
 drivers/net/tg3.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)



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David Miller - Oct. 22, 2011, 7:30 a.m.
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Sat, 22 Oct 2011 09:25:38 +0200

> Ari got kernel panics using tg3 NIC, and bisected to 2669069aacc9 "tg3:
> enable transmit time stamping."
> 
> This is because tigon3_dma_hwbug_workaround() might alloc a new skb and
> free the original. We panic when skb_tx_timestamp() is called on freed
> skb.
> 
> Reported-by: Ari Savolainen <ari.m.savolainen@gmail.com>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Applied, thanks Eric.
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Ari Savolainen - Oct. 22, 2011, 7:54 a.m.
I tried a similar patch earlier and got another panic with that. I was
quite tired at that time and may have made a mistake. I'll test Eric's
patch either later today or tomorrow.

Ari

2011/10/22 Eric Dumazet <eric.dumazet@gmail.com>:
> Ari got kernel panics using tg3 NIC, and bisected to 2669069aacc9 "tg3:
> enable transmit time stamping."
>
> This is because tigon3_dma_hwbug_workaround() might alloc a new skb and
> free the original. We panic when skb_tx_timestamp() is called on freed
> skb.
>
> Reported-by: Ari Savolainen <ari.m.savolainen@gmail.com>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> ---
>  drivers/net/tg3.c |    8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
> index 4a1374d..6149dc5 100644
> --- a/drivers/net/tg3.c
> +++ b/drivers/net/tg3.c
> @@ -6029,12 +6029,12 @@ static void tg3_tx_skb_unmap(struct tg3_napi *tnapi, u32 entry, int last)
>
>  /* Workaround 4GB and 40-bit hardware DMA bugs. */
>  static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
> -                                      struct sk_buff *skb,
> +                                      struct sk_buff **pskb,
>                                       u32 *entry, u32 *budget,
>                                       u32 base_flags, u32 mss, u32 vlan)
>  {
>        struct tg3 *tp = tnapi->tp;
> -       struct sk_buff *new_skb;
> +       struct sk_buff *new_skb, *skb = *pskb;
>        dma_addr_t new_addr = 0;
>        int ret = 0;
>
> @@ -6076,7 +6076,7 @@ static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
>        }
>
>        dev_kfree_skb(skb);
> -
> +       *pskb = new_skb;
>        return ret;
>  }
>
> @@ -6305,7 +6305,7 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
>                 */
>                entry = tnapi->tx_prod;
>                budget = tg3_tx_avail(tnapi);
> -               if (tigon3_dma_hwbug_workaround(tnapi, skb, &entry, &budget,
> +               if (tigon3_dma_hwbug_workaround(tnapi, &skb, &entry, &budget,
>                                                base_flags, mss, vlan))
>                        goto out_unlock;
>        }
>
>
>
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Ari Savolainen - Oct. 22, 2011, 1:30 p.m.
I tested the patch. It works. The panics are gone.

Thanks,
Ari

2011/10/22 Ari Savolainen <ari.m.savolainen@gmail.com>:
> I tried a similar patch earlier and got another panic with that. I was
> quite tired at that time and may have made a mistake. I'll test Eric's
> patch either later today or tomorrow.
>
> Ari
>
> 2011/10/22 Eric Dumazet <eric.dumazet@gmail.com>:
>> Ari got kernel panics using tg3 NIC, and bisected to 2669069aacc9 "tg3:
>> enable transmit time stamping."
>>
>> This is because tigon3_dma_hwbug_workaround() might alloc a new skb and
>> free the original. We panic when skb_tx_timestamp() is called on freed
>> skb.
>>
>> Reported-by: Ari Savolainen <ari.m.savolainen@gmail.com>
>> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
>> ---
>>  drivers/net/tg3.c |    8 ++++----
>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
>> index 4a1374d..6149dc5 100644
>> --- a/drivers/net/tg3.c
>> +++ b/drivers/net/tg3.c
>> @@ -6029,12 +6029,12 @@ static void tg3_tx_skb_unmap(struct tg3_napi *tnapi, u32 entry, int last)
>>
>>  /* Workaround 4GB and 40-bit hardware DMA bugs. */
>>  static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
>> -                                      struct sk_buff *skb,
>> +                                      struct sk_buff **pskb,
>>                                       u32 *entry, u32 *budget,
>>                                       u32 base_flags, u32 mss, u32 vlan)
>>  {
>>        struct tg3 *tp = tnapi->tp;
>> -       struct sk_buff *new_skb;
>> +       struct sk_buff *new_skb, *skb = *pskb;
>>        dma_addr_t new_addr = 0;
>>        int ret = 0;
>>
>> @@ -6076,7 +6076,7 @@ static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
>>        }
>>
>>        dev_kfree_skb(skb);
>> -
>> +       *pskb = new_skb;
>>        return ret;
>>  }
>>
>> @@ -6305,7 +6305,7 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
>>                 */
>>                entry = tnapi->tx_prod;
>>                budget = tg3_tx_avail(tnapi);
>> -               if (tigon3_dma_hwbug_workaround(tnapi, skb, &entry, &budget,
>> +               if (tigon3_dma_hwbug_workaround(tnapi, &skb, &entry, &budget,
>>                                                base_flags, mss, vlan))
>>                        goto out_unlock;
>>        }
>>
>>
>>
>
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Patch

diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index 4a1374d..6149dc5 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -6029,12 +6029,12 @@  static void tg3_tx_skb_unmap(struct tg3_napi *tnapi, u32 entry, int last)
 
 /* Workaround 4GB and 40-bit hardware DMA bugs. */
 static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
-				       struct sk_buff *skb,
+				       struct sk_buff **pskb,
 				       u32 *entry, u32 *budget,
 				       u32 base_flags, u32 mss, u32 vlan)
 {
 	struct tg3 *tp = tnapi->tp;
-	struct sk_buff *new_skb;
+	struct sk_buff *new_skb, *skb = *pskb;
 	dma_addr_t new_addr = 0;
 	int ret = 0;
 
@@ -6076,7 +6076,7 @@  static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
 	}
 
 	dev_kfree_skb(skb);
-
+	*pskb = new_skb;
 	return ret;
 }
 
@@ -6305,7 +6305,7 @@  static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		 */
 		entry = tnapi->tx_prod;
 		budget = tg3_tx_avail(tnapi);
-		if (tigon3_dma_hwbug_workaround(tnapi, skb, &entry, &budget,
+		if (tigon3_dma_hwbug_workaround(tnapi, &skb, &entry, &budget,
 						base_flags, mss, vlan))
 			goto out_unlock;
 	}