[PATCH net-next 1/3] skbuff: Add skb_list_linearize()

[PATCH net-next 1/3] skbuff: Add skb_list_linearize()

[Pravin B Shelar]

similar to skb_linearize(), this API takes skb list as arg and
linearize it into one big skb. STT driver patch will use this.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
---
 include/linux/skbuff.h |  2 ++
 net/core/skbuff.c      | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 85ab7d7..c9194c1 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2532,6 +2532,8 @@ static inline int skb_linearize(struct sk_buff *skb)
 	return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
 }
 
+int skb_list_linearize(struct sk_buff *head, gfp_t gfp_mask);
+
 /**
  * skb_has_shared_frag - can any frag be overwritten
  * @skb: buffer to test
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 56db472..9ef2881 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2329,6 +2329,41 @@ void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
 }
 EXPORT_SYMBOL(skb_copy_and_csum_dev);
 
+int skb_list_linearize(struct sk_buff *head, gfp_t gfp_mask)
+{
+	struct sk_buff *skb;
+	int tlen = 0;
+	int err;
+
+	err = skb_linearize(head);
+	if (err)
+		return err;
+
+	skb = head->next;
+	while (skb) {
+		tlen += skb->len;
+		skb = skb->next;
+	}
+	err = pskb_expand_head(head, 0, tlen, gfp_mask);
+	if (err)
+		return err;
+
+	skb = head->next;
+	while (skb) {
+		err = skb_copy_bits(skb, 0, skb_tail_pointer(head), skb->len);
+		if (err)
+			return err;
+		head->tail += skb->len;
+		skb = skb->next;
+	}
+	kfree_skb_list(head->next);
+	head->next = NULL;
+	head->len += tlen;
+	head->truesize = SKB_TRUESIZE(skb_end_offset(head));
+	return 0;
+}
+EXPORT_SYMBOL(skb_list_linearize);
+
 /**
  *	skb_dequeue - remove from the head of the queue
  *	@list: list to dequeue from
-- 
1.9.1

RE: [PATCH net-next 1/3] skbuff: Add skb_list_linearize()

[Harout Hedeshian]

> -----Original Message-----
> From: netdev-owner@vger.kernel.org [mailto:netdev-owner@vger.kernel.org]
> On Behalf Of Pravin B Shelar
> Sent: Tuesday, January 20, 2015 1:26 PM
> To: davem@davemloft.net
> Cc: netdev@vger.kernel.org; Pravin B Shelar
> Subject: [PATCH net-next 1/3] skbuff: Add skb_list_linearize()
> 
> similar to skb_linearize(), this API takes skb list as arg and linearize
> it into one big skb. STT driver patch will use this.
> 
> Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
> ---
>  include/linux/skbuff.h |  2 ++
>  net/core/skbuff.c      | 35 +++++++++++++++++++++++++++++++++++
>  2 files changed, 37 insertions(+)
> 
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index
> 85ab7d7..c9194c1 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -2532,6 +2532,8 @@ static inline int skb_linearize(struct sk_buff
> *skb)
>  	return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;  }
> 
> +int skb_list_linearize(struct sk_buff *head, gfp_t gfp_mask);
> +
>  /**
>   * skb_has_shared_frag - can any frag be overwritten
>   * @skb: buffer to test
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c index
> 56db472..9ef2881 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -2329,6 +2329,41 @@ void skb_copy_and_csum_dev(const struct sk_buff
> *skb, u8 *to)  }  EXPORT_SYMBOL(skb_copy_and_csum_dev);
> 
> +int skb_list_linearize(struct sk_buff *head, gfp_t gfp_mask) {
> +	struct sk_buff *skb;
> +	int tlen = 0;
> +	int err;
> +
> +	err = skb_linearize(head);
> +	if (err)
> +		return err;
> +
> +	skb = head->next;
> +	while (skb) {
> +		tlen += skb->len;
> +		skb = skb->next;
> +	}
> +	err = pskb_expand_head(head, 0, tlen, gfp_mask);
> +	if (err)
> +		return err;
> +
> +	skb = head->next;
> +	while (skb) {
> +		err = skb_copy_bits(skb, 0, skb_tail_pointer(head),
skb->len);
> +		if (err)
> +			return err;
> +		head->tail += skb->len;
> +		skb = skb->next;
> +	}
> +	kfree_skb_list(head->next);
> +	head->next = NULL;
> +	head->len += tlen;
> +	head->truesize = SKB_TRUESIZE(skb_end_offset(head));
> +	return 0;
> +}
> +EXPORT_SYMBOL(skb_list_linearize);
> +
>  /**
>   *	skb_dequeue - remove from the head of the queue
>   *	@list: list to dequeue from
> --
> 1.9.1
> 

This looks useful for us as well.

Acked-by: Harout Hedeshian <harouth@codeaurora.org>

Thanks,
Harout

--
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
Foundation Collaborative Project

Re: [PATCH net-next 1/3] skbuff: Add skb_list_linearize()

[Eric Dumazet]

On Tue, 2015-01-20 at 12:25 -0800, Pravin B Shelar wrote:
> similar to skb_linearize(), this API takes skb list as arg and
> linearize it into one big skb. STT driver patch will use this.
> 
> Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
> ---
>  include/linux/skbuff.h |  2 ++
>  net/core/skbuff.c      | 35 +++++++++++++++++++++++++++++++++++
>  2 files changed, 37 insertions(+)
> 
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 85ab7d7..c9194c1 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -2532,6 +2532,8 @@ static inline int skb_linearize(struct sk_buff *skb)
>  	return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
>  }
>  
> +int skb_list_linearize(struct sk_buff *head, gfp_t gfp_mask);
> +
>  /**
>   * skb_has_shared_frag - can any frag be overwritten
>   * @skb: buffer to test
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 56db472..9ef2881 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -2329,6 +2329,41 @@ void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
>  }
>  EXPORT_SYMBOL(skb_copy_and_csum_dev);
>  
> +int skb_list_linearize(struct sk_buff *head, gfp_t gfp_mask)
> +{
> +	struct sk_buff *skb;
> +	int tlen = 0;
> +	int err;
> +
> +	err = skb_linearize(head);
> +	if (err)
> +		return err;
> +
> +	skb = head->next;
> +	while (skb) {
> +		tlen += skb->len;
> +		skb = skb->next;
> +	}
> +	err = pskb_expand_head(head, 0, tlen, gfp_mask);
> +	if (err)
> +		return err;
> +
> +	skb = head->next;
> +	while (skb) {
> +		err = skb_copy_bits(skb, 0, skb_tail_pointer(head), skb->len);
> +		if (err)
> +			return err;
> +		head->tail += skb->len;
> +		skb = skb->next;
> +	}
> +	kfree_skb_list(head->next);
> +	head->next = NULL;
> +	head->len += tlen;
> +	head->truesize = SKB_TRUESIZE(skb_end_offset(head));

This is buggy : skb can have a destructor, like sock_wfree()

Re: [PATCH net-next 1/3] skbuff: Add skb_list_linearize()

[Pravin Shelar]

On Tue, Jan 20, 2015 at 1:43 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Tue, 2015-01-20 at 12:25 -0800, Pravin B Shelar wrote:
>> similar to skb_linearize(), this API takes skb list as arg and
>> linearize it into one big skb. STT driver patch will use this.
>>
>> Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
>> ---
...
>> @@ -2329,6 +2329,41 @@ void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
>>  }
>>  EXPORT_SYMBOL(skb_copy_and_csum_dev);
>>
>> +int skb_list_linearize(struct sk_buff *head, gfp_t gfp_mask)
>> +{
>> +     struct sk_buff *skb;
>> +     int tlen = 0;
>> +     int err;
>> +
>> +     err = skb_linearize(head);
>> +     if (err)
>> +             return err;
>> +
>> +     skb = head->next;
>> +     while (skb) {
>> +             tlen += skb->len;
>> +             skb = skb->next;
>> +     }
>> +     err = pskb_expand_head(head, 0, tlen, gfp_mask);
>> +     if (err)
>> +             return err;
>> +
>> +     skb = head->next;
>> +     while (skb) {
>> +             err = skb_copy_bits(skb, 0, skb_tail_pointer(head), skb->len);
>> +             if (err)
>> +                     return err;
>> +             head->tail += skb->len;
>> +             skb = skb->next;
>> +     }
>> +     kfree_skb_list(head->next);
>> +     head->next = NULL;
>> +     head->len += tlen;
>> +     head->truesize = SKB_TRUESIZE(skb_end_offset(head));
>
> This is buggy : skb can have a destructor, like sock_wfree()
>

In current use-case it is never called for skb which is tied to
socket. But I agree it need to be fixed. I can call skb_orphan() to
fix it.

Thanks.

Re: [PATCH net-next 1/3] skbuff: Add skb_list_linearize()

[Eric Dumazet]

On Tue, 2015-01-20 at 14:46 -0800, Pravin Shelar wrote:

> In current use-case it is never called for skb which is tied to
> socket. But I agree it need to be fixed. I can call skb_orphan() to
> fix it.

I would do nothing at all, like skb_linearize()