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[4.2.y-ckt,stable] Patch "xen-netback: don't use last request to determine minimum Tx credit" has been added to the 4.2.y-ckt tree

Message ID 1452902230-28091-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa Jan. 15, 2016, 11:57 p.m. UTC 
This is a note to let you know that I have just added a patch titled

    xen-netback: don't use last request to determine minimum Tx credit

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt2.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

From 15d616f91f5d97eec34be0929cef9b5d47a7150f Mon Sep 17 00:00:00 2001
From: David Vrabel <david.vrabel@citrix.com>
Date: Fri, 30 Oct 2015 15:16:01 +0000
Subject: xen-netback: don't use last request to determine minimum Tx credit

commit 0f589967a73f1f30ab4ac4dd9ce0bb399b4d6357 upstream.

The last from guest transmitted request gives no indication about the
minimum amount of credit that the guest might need to send a packet
since the last packet might have been a small one.

Instead allow for the worst case 128 KiB packet.

This is part of XSA155.

Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 drivers/net/xen-netback/netback.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--
1.9.1
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Patch

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 3f44b52..a31451e 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -625,9 +625,7 @@  static void tx_add_credit(struct xenvif_queue *queue)
 	 * Allow a burst big enough to transmit a jumbo packet of up to 128kB.
 	 * Otherwise the interface can seize up due to insufficient credit.
 	 */
-	max_burst = RING_GET_REQUEST(&queue->tx, queue->tx.req_cons)->size;
-	max_burst = min(max_burst, 131072UL);
-	max_burst = max(max_burst, queue->credit_bytes);
+	max_burst = max(131072UL, queue->credit_bytes);

 	/* Take care that adding a new chunk of credit doesn't wrap to zero. */
 	max_credit = queue->remaining_credit + queue->credit_bytes;