@@ -144,6 +144,11 @@ static bool e1000_clean_rx_irq(struct e1000_adapter *adapter,
static bool e1000_clean_jumbo_rx_irq(struct e1000_adapter *adapter,
struct e1000_rx_ring *rx_ring,
int *work_done, int work_to_do);
+static void e1000_alloc_dummy_rx_buffers(struct e1000_adapter *adapter,
+ struct e1000_rx_ring *rx_ring,
+ int cleaned_count)
+{
+}
static void e1000_alloc_rx_buffers(struct e1000_adapter *adapter,
struct e1000_rx_ring *rx_ring,
int cleaned_count);
@@ -3525,8 +3530,11 @@ static int e1000_change_mtu(struct net_device *netdev, int new_mtu)
msleep(1);
/* e1000_down has a dependency on max_frame_size */
hw->max_frame_size = max_frame;
- if (netif_running(netdev))
+ if (netif_running(netdev)) {
+ /* prevent buffers from being reallocated */
+ adapter->alloc_rx_buf = e1000_alloc_dummy_rx_buffers;
e1000_down(adapter);
+ }
/* NOTE: netdev_alloc_skb reserves 16 bytes, and typically NET_IP_ALIGN
* means we reserve 2 more, this pushes us to allocate from the next
This is a note to let you know that I have just added a patch titled e1000: add dummy allocator to fix race condition between mtu change and netpoll to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt11. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 33f8b8ded73465e5162f87005f1a181572392c5e Mon Sep 17 00:00:00 2001 From: Sabrina Dubroca <sd@queasysnail.net> Date: Thu, 26 Feb 2015 05:35:41 +0000 Subject: e1000: add dummy allocator to fix race condition between mtu change and netpoll commit 08e8331654d1d7b2c58045e549005bc356aa7810 upstream. There is a race condition between e1000_change_mtu's cleanups and netpoll, when we change the MTU across jumbo size: Changing MTU frees all the rx buffers: e1000_change_mtu -> e1000_down -> e1000_clean_all_rx_rings -> e1000_clean_rx_ring Then, close to the end of e1000_change_mtu: pr_info -> ... -> netpoll_poll_dev -> e1000_clean -> e1000_clean_rx_irq -> e1000_alloc_rx_buffers -> e1000_alloc_frag And when we come back to do the rest of the MTU change: e1000_up -> e1000_configure -> e1000_configure_rx -> e1000_alloc_jumbo_rx_buffers alloc_jumbo finds the buffers already != NULL, since data (shared with page in e1000_rx_buffer->rxbuf) has been re-alloc'd, but it's garbage, or at least not what is expected when in jumbo state. This results in an unusable adapter (packets don't get through), and a NULL pointer dereference on the next call to e1000_clean_rx_ring (other mtu change, link down, shutdown): BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff81194d6e>] put_compound_page+0x7e/0x330 [...] Call Trace: [<ffffffff81195445>] put_page+0x55/0x60 [<ffffffff815d9f44>] e1000_clean_rx_ring+0x134/0x200 [<ffffffff815da055>] e1000_clean_all_rx_rings+0x45/0x60 [<ffffffff815df5e0>] e1000_down+0x1c0/0x1d0 [<ffffffff811e2260>] ? deactivate_slab+0x7f0/0x840 [<ffffffff815e21bc>] e1000_change_mtu+0xdc/0x170 [<ffffffff81647050>] dev_set_mtu+0xa0/0x140 [<ffffffff81664218>] do_setlink+0x218/0xac0 [<ffffffff814459e9>] ? nla_parse+0xb9/0x120 [<ffffffff816652d0>] rtnl_newlink+0x6d0/0x890 [<ffffffff8104f000>] ? kvm_clock_read+0x20/0x40 [<ffffffff810a2068>] ? sched_clock_cpu+0xa8/0x100 [<ffffffff81663802>] rtnetlink_rcv_msg+0x92/0x260 By setting the allocator to a dummy version, netpoll can't mess up our rx buffers. The allocator is set back to a sane value in e1000_configure_rx. Fixes: edbbb3ca1077 ("e1000: implement jumbo receive with partial descriptors") Signed-off-by: Sabrina Dubroca <sd@queasysnail.net> Tested-by: Aaron Brown <aaron.f.brown@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/net/ethernet/intel/e1000/e1000_main.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)