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net: Unmap fragment page once iterator is done

PATCH In review Wedson Almeida Filho 2 participants 7 messages Jun 25, 2013 – Jun 28, 2013

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Networking Network drivers SCSI Batman advanced +1 more subsystems
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Wedson Almeida Filho

author
#0 lore raw

PATCH v3 1/1 net: Unmap fragment page once iterator is done

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 <[email protected]>
---
 drivers/scsi/libiscsi_tcp.c |    1 -
 net/batman-adv/main.c       |    1 -
 net/core/skbuff.c           |    7 ++++++-
 3 files changed, 6 insertions(+), 3 deletions(-)
drivers/scsi/libiscsi_tcp.c +0 -1
index 552e8a2..448eae8 100644
@@ -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);
net/batman-adv/main.c +0 -1
index 51aafd6..08125f3 100644
@@ -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);
 }
net/core/skbuff.c +6 -1
index cfd777b..26ea1cf 100644
@@ -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;
Signature · 1 line
1.7.9.5
maintainer
#1 lore raw

From: Wedson Almeida Filho <[email protected]>
Date: Mon, 24 Jun 2013 18:25:20 -0700

Quoted 11 lines

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 <[email protected]>

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

Thanks.

author
#2 lore raw
Quoted 2 lines · David Miller

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

author
#3 lore raw
Quoted 5 lines
Quoted 2 lines

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

maintainer
#4 lore raw

From: Wedson Almeida Filho <[email protected]>
Date: Thu, 27 Jun 2013 15:03:40 -0700

Quoted 9 lines
Quoted 5 lines
Quoted 2 lines

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.

author
#5 lore raw
Quoted 6 lines · David Miller
Quoted 3 lines

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.

maintainer
#6 lore raw

From: Wedson Almeida Filho <[email protected]>
Date: Thu, 27 Jun 2013 17:35:15 -0700

Quoted 6 lines · David Miller
Quoted 5 lines
Quoted 4 lines

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).

Quoted 7 lines
Quoted 2 lines

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.