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authorChris Leech <christopher.leech@intel.com>2009-11-03 11:50:05 -0800
committerJames Bottomley <James.Bottomley@suse.de>2009-12-04 12:01:25 -0600
commit18fa11efc279c20af5eefff2bbe814ca067e51ae (patch)
treefc8b911554aa04c1ed7f6a5ebe31ef6aa2ea0379 /drivers/scsi/fcoe
parentcc0136c2e9c10e889cb36e39710c0eb10707b396 (diff)
[SCSI] libfc, fcoe: fixes for highmem skb linearize panics
There are cases outside of our control that may result in a transmit skb being linearized in dev_queue_xmit. There are a couple of bugs in libfc/fcoe that can result in a panic at that point. This patch contains two fixes to prevent those panics. 1) use fast cloning instead of shared skbs with dev_queue_xmit dev_queue_xmit doen't want shared skbuffs being passed in, and __skb_linearize will BUG if the skb is shared. FCoE is holding an extra reference around the call to dev_queue_xmit, so that when it returns an error code indicating the frame has been dropped it can maintain it's own backlog and retransmit. Switch to using fast skb cloning for this instead. 2) don't append compound pages as > PAGE_SIZE skb fragments fc_fcp_send_data will append pages from a scatterlist to the nr_frags[] if the netdev supports it. But, it's using > PAGE_SIZE compound pages as a single skb_frag. In the highmem linearize case that page will be passed to kmap_atomic to get a mapping to copy out of, but kmap_atomic will only allow access to the first PAGE_SIZE part. The memcpy will keep going and cause a page fault once is crosses the first boundary. If fc_fcp_send_data uses linear buffers from the start, it calls kmap_atomic one PAGE_SIZE at a time. That same logic needs to be applied when setting up skb_frags. Signed-off-by: Chris Leech <christopher.leech@intel.com> Signed-off-by: Robert Love <robert.w.love@intel.com> Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Diffstat (limited to 'drivers/scsi/fcoe')
-rw-r--r--drivers/scsi/fcoe/fcoe.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index 28029a342892..b570f39faa3a 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -1267,10 +1267,11 @@ err2:
*/
static inline int fcoe_start_io(struct sk_buff *skb)
{
+ struct sk_buff *nskb;
int rc;
- skb_get(skb);
- rc = dev_queue_xmit(skb);
+ nskb = skb_clone(skb, GFP_ATOMIC);
+ rc = dev_queue_xmit(nskb);
if (rc != 0)
return rc;
kfree_skb(skb);