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由 Andrew Gallatin 提交于
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: NJeff Garzik <jeff@garzik.org>
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