netdev - [PATCH V2] Netvsc: Call hv_unmap_memory() in the netvsc_device

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Date:   Tue,  8 Feb 2022 09:26:52 -0500
From:   Tianyu Lan <ltykernel@...il.com>
To:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        wei.liu@...nel.org, decui@...rosoft.com, davem@...emloft.net,
        kuba@...nel.org, michael.h.kelley@...rosoft.com
Cc:     Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org
Subject: [PATCH V2] Netvsc: Call hv_unmap_memory() in the netvsc_device_remove()

From: Tianyu Lan <Tianyu.Lan@...rosoft.com>

netvsc_device_remove() calls vunmap() inside which should not be
called in the interrupt context. Current code calls hv_unmap_memory()
in the free_netvsc_device() which is rcu callback and maybe called
in the interrupt context. This will trigger BUG_ON(in_interrupt())
in the vunmap(). Fix it via moving hv_unmap_memory() to netvsc_device_
remove().

Fixes: 846da38de0e8 ("net: netvsc: Add Isolation VM support for netvsc driver")
Signed-off-by: Tianyu Lan <Tianyu.Lan@...rosoft.com>
---
Change since v1:
	* Call hv_unmap_memory() before free_netvsc_device() in the
	  netvsc_device_remove().
---
 drivers/net/hyperv/netvsc.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index afa81a9480cc..e675d1016c3c 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -154,19 +154,15 @@ static void free_netvsc_device(struct rcu_head *head)
 
 	kfree(nvdev->extension);
 
-	if (nvdev->recv_original_buf) {
-		hv_unmap_memory(nvdev->recv_buf);
+	if (nvdev->recv_original_buf)
 		vfree(nvdev->recv_original_buf);
-	} else {
+	else
 		vfree(nvdev->recv_buf);
-	}
 
-	if (nvdev->send_original_buf) {
-		hv_unmap_memory(nvdev->send_buf);
+	if (nvdev->send_original_buf)
 		vfree(nvdev->send_original_buf);
-	} else {
+	else
 		vfree(nvdev->send_buf);
-	}
 
 	bitmap_free(nvdev->send_section_map);
 
@@ -765,6 +761,12 @@ void netvsc_device_remove(struct hv_device *device)
 		netvsc_teardown_send_gpadl(device, net_device, ndev);
 	}
 
+	if (net_device->recv_original_buf)
+		hv_unmap_memory(net_device->recv_buf);
+
+	if (net_device->send_original_buf)
+		hv_unmap_memory(net_device->send_buf);
+
 	/* Release all resources */
 	free_netvsc_device_rcu(net_device);
 }
@@ -1821,6 +1823,12 @@ struct netvsc_device *netvsc_device_add(struct hv_device *device,
 	netif_napi_del(&net_device->chan_table[0].napi);
 
 cleanup2:
+	if (net_device->recv_original_buf)
+		hv_unmap_memory(net_device->recv_buf);
+
+	if (net_device->send_original_buf)
+		hv_unmap_memory(net_device->send_buf);
+
 	free_netvsc_device(&net_device->rcu);
 
 	return ERR_PTR(ret);
-- 
2.25.1