Patchwork [v3] net: Unmap fragment page once iterator is done

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Submitter Wedson Almeida Filho
Date June 25, 2013, 1:25 a.m.
Message ID <1372123520-18287-1-git-send-email-wedsonaf@gmail.com>
Download mbox | patch
Permalink /patch/253996/
State Changes Requested
Delegated to: David Miller
Headers show

Comments

Wedson Almeida Filho - June 25, 2013, 1:25 a.m.
Callers of skb_seq_read() are currently forced to call skb_abort_seq_read()
even when consuming all the data because the last call to skb_seq_read (the
one that returns 0 to indicate the end) fails to unmap the last fragment page.

With this patch callers will be allowed to traverse the SKB data by calling
skb_prepare_seq_read() once and repeatedly calling skb_seq_read() as originally
intended (and documented in the original commit 677e90eda - "[NET]: Zerocopy
sequential reading of skb data"), that is, only call skb_abort_seq_read() if
the sequential read is actually aborted.

Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
---
 drivers/scsi/libiscsi_tcp.c |    1 -
 net/batman-adv/main.c       |    1 -
 net/core/skbuff.c           |    7 ++++++-
 3 files changed, 6 insertions(+), 3 deletions(-)
David Miller - June 25, 2013, 11:20 p.m.
From: Wedson Almeida Filho <wedsonaf@gmail.com>
Date: Mon, 24 Jun 2013 18:25:20 -0700

> Callers of skb_seq_read() are currently forced to call skb_abort_seq_read()
> even when consuming all the data because the last call to skb_seq_read (the
> one that returns 0 to indicate the end) fails to unmap the last fragment page.
> 
> With this patch callers will be allowed to traverse the SKB data by calling
> skb_prepare_seq_read() once and repeatedly calling skb_seq_read() as originally
> intended (and documented in the original commit 677e90eda - "[NET]: Zerocopy
> sequential reading of skb data"), that is, only call skb_abort_seq_read() if
> the sequential read is actually aborted.
> 
> Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>

This patch doesn't even come close to applying to the net-next tree,
please respin this patch properly and resubmit.

Thanks.
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Wedson Almeida Filho - June 25, 2013, 11:44 p.m.
On Tue, Jun 25, 2013 at 4:20 PM, David Miller <davem@davemloft.net> wrote:

> This patch doesn't even come close to applying to the net-next tree,
> please respin this patch properly and resubmit.

Where can I pull the net-next tree from?
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git?

Thanks
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Wedson Almeida Filho - June 27, 2013, 10:03 p.m.
>> This patch doesn't even come close to applying to the net-next tree,
>> please respin this patch properly and resubmit.
>
> Where can I pull the net-next tree from?
> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git?

David, would you mind clarifying where I can find net-next? The only
one I could find was the one I mention above and it already has my
patch in it (though with the previous comment).

Thanks
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David Miller - June 27, 2013, 11:22 p.m.
From: Wedson Almeida Filho <wedsonaf@gmail.com>
Date: Thu, 27 Jun 2013 15:03:40 -0700

>>> This patch doesn't even come close to applying to the net-next tree,
>>> please respin this patch properly and resubmit.
>>
>> Where can I pull the net-next tree from?
>> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git?
> 
> David, would you mind clarifying where I can find net-next? The only
> one I could find was the one I mention above and it already has my
> patch in it (though with the previous comment).

Yes that is where my net-next tree is, as clearly stated the
"NETWORKING [GENERAL]" sercion of the MAINTAINERS file.
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Wedson Almeida Filho - June 28, 2013, 12:35 a.m.
On Thu, Jun 27, 2013 at 4:22 PM, David Miller <davem@davemloft.net> wrote:

>> David, would you mind clarifying where I can find net-next? The only
>> one I could find was the one I mention above and it already has my
>> patch in it (though with the previous comment).
>
> Yes that is where my net-next tree is, as clearly stated the
> "NETWORKING [GENERAL]" sercion of the MAINTAINERS file.

Ok, thanks for the info, now I know where the definitive answer is.

Anyway, why are you asking me to respin this patch? If I do it based
on this tree, there will be no changes in it.
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David Miller - June 28, 2013, 1:04 a.m.
From: Wedson Almeida Filho <wedsonaf@gmail.com>
Date: Thu, 27 Jun 2013 17:35:15 -0700

> On Thu, Jun 27, 2013 at 4:22 PM, David Miller <davem@davemloft.net> wrote:
> 
>>> David, would you mind clarifying where I can find net-next? The only
>>> one I could find was the one I mention above and it already has my
>>> patch in it (though with the previous comment).
>>
>> Yes that is where my net-next tree is, as clearly stated the
>> "NETWORKING [GENERAL]" sercion of the MAINTAINERS file.
> 
> Ok, thanks for the info, now I know where the definitive answer is.
> 
> Anyway, why are you asking me to respin this patch? If I do it based
> on this tree, there will be no changes in it.

Nevermind then.
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Patch

diff --git a/drivers/scsi/libiscsi_tcp.c b/drivers/scsi/libiscsi_tcp.c
index 552e8a2..448eae8 100644
--- a/drivers/scsi/libiscsi_tcp.c
+++ b/drivers/scsi/libiscsi_tcp.c
@@ -906,7 +906,6 @@  int iscsi_tcp_recv_skb(struct iscsi_conn *conn, struct sk_buff *skb,
 			ISCSI_DBG_TCP(conn, "no more data avail. Consumed %d\n",
 				      consumed);
 			*status = ISCSI_TCP_SKB_DONE;
-			skb_abort_seq_read(&seq);
 			goto skb_done;
 		}
 		BUG_ON(segment->copied >= segment->size);
diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index 51aafd6..08125f3 100644
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -473,7 +473,6 @@  __be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr)
 		crc = crc32c(crc, data, len);
 		consumed += len;
 	}
-	skb_abort_seq_read(&st);
 
 	return htonl(crc);
 }
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index cfd777b..26ea1cf 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2554,8 +2554,13 @@  unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
 	unsigned int block_limit, abs_offset = consumed + st->lower_offset;
 	skb_frag_t *frag;
 
-	if (unlikely(abs_offset >= st->upper_offset))
+	if (unlikely(abs_offset >= st->upper_offset)) {
+		if (st->frag_data) {
+			kunmap_atomic(st->frag_data);
+			st->frag_data = NULL;
+		}
 		return 0;
+	}
 
 next_skb:
 	block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;