From ac5047671758ad4be9f93898247b3a8b6dfde4c7 Mon Sep 17 00:00:00 2001 From: "Andrea Parri (Microsoft)" Date: Mon, 6 Apr 2020 02:15:07 +0200 Subject: [PATCH] hv_netvsc: Disable NAPI before closing the VMBus channel vmbus_chan_sched() might call the netvsc driver callback function that ends up scheduling NAPI work. This "work" can access the channel ring buffer, so we must ensure that any such work is completed and that the ring buffer is no longer being accessed before freeing the ring buffer data structure in the channel closure path. To this end, disable NAPI before calling vmbus_close() in netvsc_device_remove(). Suggested-by: Michael Kelley Signed-off-by: Andrea Parri (Microsoft) Acked-by: Stephen Hemminger Cc: "David S. Miller" Cc: Link: https://lore.kernel.org/r/20200406001514.19876-5-parri.andrea@gmail.com Reviewed-by: Michael Kelley Signed-off-by: Wei Liu --- drivers/hv/channel.c | 6 ++++++ drivers/net/hyperv/netvsc.c | 7 +++++-- 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c index 23f358cb7f49..256ee90c7446 100644 --- a/drivers/hv/channel.c +++ b/drivers/hv/channel.c @@ -609,6 +609,12 @@ void vmbus_reset_channel_cb(struct vmbus_channel *channel) * the former is accessing channel->inbound.ring_buffer, the latter * could be freeing the ring_buffer pages, so here we must stop it * first. + * + * vmbus_chan_sched() might call the netvsc driver callback function + * that ends up scheduling NAPI work that accesses the ring buffer. + * At this point, we have to ensure that any such work is completed + * and that the channel ring buffer is no longer being accessed, cf. + * the calls to napi_disable() in netvsc_device_remove(). */ tasklet_disable(&channel->callback_event); diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c index ca68aa1df801..41f5cf0bb997 100644 --- a/drivers/net/hyperv/netvsc.c +++ b/drivers/net/hyperv/netvsc.c @@ -636,9 +636,12 @@ void netvsc_device_remove(struct hv_device *device) RCU_INIT_POINTER(net_device_ctx->nvdev, NULL); - /* And disassociate NAPI context from device */ - for (i = 0; i < net_device->num_chn; i++) + /* 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); netif_napi_del(&net_device->chan_table[i].napi); + } /* * At this point, no one should be accessing net_device