From b96ed2c97c791954abc881ef384e773010945aec Mon Sep 17 00:00:00 2001 From: Jiri Pirko Date: Wed, 14 Aug 2024 14:25:00 +0200 Subject: [PATCH] virtio_net: move netdev_tx_reset_queue() call before RX napi enable MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit During suspend/resume the following BUG was hit: ------------[ cut here ]------------ kernel BUG at lib/dynamic_queue_limits.c:99! Internal error: Oops - BUG: 0 [#1] SMP ARM Modules linked in: bluetooth ecdh_generic ecc libaes CPU: 1 PID: 1282 Comm: rtcwake Not tainted 6.10.0-rc3-00732-gc8bd1f7f3e61 #15240 Hardware name: Generic DT based system PC is at dql_completed+0x270/0x2cc LR is at __free_old_xmit+0x120/0x198 pc : []    lr : []    psr: 80000013 ... Flags: Nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none Control: 10c5387d  Table: 43a4406a  DAC: 00000051 ... Process rtcwake (pid: 1282, stack limit = 0xfbc21278) Stack: (0xe0805e80 to 0xe0806000) ... Call trace:  dql_completed from __free_old_xmit+0x120/0x198  __free_old_xmit from free_old_xmit+0x44/0xe4  free_old_xmit from virtnet_poll_tx+0x88/0x1b4  virtnet_poll_tx from __napi_poll+0x2c/0x1d4  __napi_poll from net_rx_action+0x140/0x2b4  net_rx_action from handle_softirqs+0x11c/0x350  handle_softirqs from call_with_stack+0x18/0x20  call_with_stack from do_softirq+0x48/0x50  do_softirq from __local_bh_enable_ip+0xa0/0xa4  __local_bh_enable_ip from virtnet_open+0xd4/0x21c  virtnet_open from virtnet_restore+0x94/0x120  virtnet_restore from virtio_device_restore+0x110/0x1f4  virtio_device_restore from dpm_run_callback+0x3c/0x100  dpm_run_callback from device_resume+0x12c/0x2a8  device_resume from dpm_resume+0x12c/0x1e0  dpm_resume from dpm_resume_end+0xc/0x18  dpm_resume_end from suspend_devices_and_enter+0x1f0/0x72c  suspend_devices_and_enter from pm_suspend+0x270/0x2a0  pm_suspend from state_store+0x68/0xc8  state_store from kernfs_fop_write_iter+0x10c/0x1cc  kernfs_fop_write_iter from vfs_write+0x2b0/0x3dc  vfs_write from ksys_write+0x5c/0xd4  ksys_write from ret_fast_syscall+0x0/0x54 Exception stack(0xe8bf1fa8 to 0xe8bf1ff0) ... ---[ end trace 0000000000000000 ]--- After virtnet_napi_enable() is called, the following path is hit: __napi_poll() -> virtnet_poll() -> virtnet_poll_cleantx() -> netif_tx_wake_queue() That wakes the TX queue and allows skbs to be submitted and accounted by BQL counters. Then netdev_tx_reset_queue() is called that resets BQL counters and eventually leads to the BUG in dql_completed(). Move virtnet_napi_tx_enable() what does BQL counters reset before RX napi enable to avoid the issue. Reported-by: Marek Szyprowski Closes: https://lore.kernel.org/netdev/e632e378-d019-4de7-8f13-07c572ab37a9@samsung.com/ Fixes: c8bd1f7f3e61 ("virtio_net: add support for Byte Queue Limits") Tested-by: Marek Szyprowski Signed-off-by: Jiri Pirko Acked-by: Michael S. Tsirkin Acked-by: Jason Wang Link: https://patch.msgid.link/20240814122500.1710279-1-jiri@resnulli.us Signed-off-by: Jakub Kicinski --- drivers/net/virtio_net.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 3f10c72743e94d..c6af189480929a 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -2867,8 +2867,8 @@ static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index) if (err < 0) goto err_xdp_reg_mem_model; - virtnet_napi_enable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi); netdev_tx_reset_queue(netdev_get_tx_queue(vi->dev, qp_index)); + virtnet_napi_enable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi); virtnet_napi_tx_enable(vi, vi->sq[qp_index].vq, &vi->sq[qp_index].napi); return 0;