In commit ac5047671758 ("hv_netvsc: Disable NAPI before closing the
VMBus channel"), napi_disable was getting called for all channels,
including all subchannels without confirming if they are enabled or not.
Which caused hv_netvsc getting hung at napi_disable, when netvsc_probe()
and netvsc_remove() are happening simultaneously and netvsc_remove()
calls cancel_work_sync(&nvdev->subchan_work) before netvsc_sc_open()
calls napi_enable for the sub channels. Which causes NAPIF_STATE_SCHED
bit not getting cleared for the subchannels.
Now during netvsc_device_remove(), when napi_disable is called for those
subchannels, napi_disable gets stuck on infinite msleep.
Call trace:
[ 654.559417] task:modprobe state:D stack: 0 pid: 2321 ppid: 1091 flags:0x00004002
[ 654.568030] Call Trace:
[ 654.571221] <TASK>
[ 654.573790] __schedule+0x2d6/0x960
[ 654.577733] schedule+0x69/0xf0
[ 654.581214] schedule_timeout+0x87/0x140
[ 654.585463] ? __bpf_trace_tick_stop+0x20/0x20
[ 654.590291] msleep+0x2d/0x40
[ 654.593625] napi_disable+0x2b/0x80
[ 654.597437] netvsc_device_remove+0x8a/0x1f0 [hv_netvsc]
[ 654.603935] rndis_filter_device_remove+0x194/0x1c0 [hv_netvsc]
[ 654.611101] ? do_wait_intr+0xb0/0xb0
[ 654.615753] netvsc_remove+0x7c/0x120 [hv_netvsc]
[ 654.621675] vmbus_remove+0x27/0x40 [hv_vmbus]
Fixes: ac5047671758 ("hv_netvsc: Disable NAPI before closing the VMBus channel")
Signed-off-by: Souradeep Chakrabarti <schakrabarti@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/hyperv/netvsc.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 1dafa44155d0..a6fcbda64ecc 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -708,7 +708,10 @@ void netvsc_device_remove(struct hv_device *device)
/* Disable NAPI and disassociate its context from the device. */
for (i = 0; i < net_device->num_chn; i++) {
/* See also vmbus_reset_channel_cb(). */
- napi_disable(&net_device->chan_table[i].napi);
+ /* only disable enabled NAPI channel */
+ if (i < ndev->real_num_rx_queues)
+ napi_disable(&net_device->chan_table[i].napi);
+
netif_napi_del(&net_device->chan_table[i].napi);
}
--
2.34.1
