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author | Andrew Gallatin <gallatin@myri.com> | 2007-10-31 17:40:06 -0400 |
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committer | Jeff Garzik <jeff@garzik.org> | 2007-11-01 16:04:45 -0400 |
commit | c956a24018819bd903fad0cd275a63c089cdba53 (patch) | |
tree | 4a7e534f589e600c11384ee3892c98f8af3d0b58 /drivers/net/myri10ge | |
parent | 48d58459fe991e48bf7e6638a0ded0f8cbd2fa3b (diff) | |
download | linux-stable-c956a24018819bd903fad0cd275a63c089cdba53.tar.gz linux-stable-c956a24018819bd903fad0cd275a63c089cdba53.tar.bz2 linux-stable-c956a24018819bd903fad0cd275a63c089cdba53.zip |
Fix myri10ge NAPI oops & warnings
When testing the myri10ge driver with 2.6.24-rc1, I found
that the machine crashed under heavy load:
Unable to handle kernel paging request at 0000000000100108 RIP:
[<ffffffff803cc8dd>] net_rx_action+0x11b/0x184
The address corresponds to the list_move_tail() in
netif_rx_complete():
if (unlikely(work == weight))
list_move_tail(&n->poll_list, list);
Eventually, I traced the crashes to calling netif_rx_complete() with
work_done == budget. From looking at other drivers, it appears that
one should only call netif_rx_complete() when work_done < budget.
To fix it, I changed the test in myri10ge_poll() so that it refers
to to work_done rather than looking at the rx ring status. If
work_done is < budget, then that implies we have no more packets to
process. Any races will be resolved by the NIC when the write to
irq_claim is made.
In myri10ge_clean_rx_done(), if we ever exceeded our budget, it would
report a work_done one larger than was acutally done. This is because
the increment was done in the conditional, so work_done would be
incremented regardless of whether or not the test passed or failed.
This would lead to the WARN_ON_ONCE(work > weight); warning in
net_rx_action triggering. I've moved the increment of work_done
inside the loop. Note that this would only be a problem when we had
exceeded our budget.
Signed off by: Andrew Gallatin <gallatin@myri.com>
Andrew Gallatin Myricom Inc
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Diffstat (limited to 'drivers/net/myri10ge')
-rw-r--r-- | drivers/net/myri10ge/myri10ge.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/net/myri10ge/myri10ge.c b/drivers/net/myri10ge/myri10ge.c index 366e62a2b1e5..0f306ddb5630 100644 --- a/drivers/net/myri10ge/myri10ge.c +++ b/drivers/net/myri10ge/myri10ge.c @@ -1151,7 +1151,7 @@ static inline int myri10ge_clean_rx_done(struct myri10ge_priv *mgp, int budget) u16 length; __wsum checksum; - while (rx_done->entry[idx].length != 0 && work_done++ < budget) { + while (rx_done->entry[idx].length != 0 && work_done < budget) { length = ntohs(rx_done->entry[idx].length); rx_done->entry[idx].length = 0; checksum = csum_unfold(rx_done->entry[idx].checksum); @@ -1167,6 +1167,7 @@ static inline int myri10ge_clean_rx_done(struct myri10ge_priv *mgp, int budget) rx_bytes += rx_ok * (unsigned long)length; cnt++; idx = cnt & (myri10ge_max_intr_slots - 1); + work_done++; } rx_done->idx = idx; rx_done->cnt = cnt; @@ -1233,13 +1234,12 @@ static int myri10ge_poll(struct napi_struct *napi, int budget) struct myri10ge_priv *mgp = container_of(napi, struct myri10ge_priv, napi); struct net_device *netdev = mgp->dev; - struct myri10ge_rx_done *rx_done = &mgp->rx_done; int work_done; /* process as many rx events as NAPI will allow */ work_done = myri10ge_clean_rx_done(mgp, budget); - if (rx_done->entry[rx_done->idx].length == 0 || !netif_running(netdev)) { + if (work_done < budget || !netif_running(netdev)) { netif_rx_complete(netdev, napi); put_be32(htonl(3), mgp->irq_claim); } |