linux-kernel - [PATCH 2/5] vmbus: suppress uevents for hv

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Date:   Sat,  9 Sep 2017 23:08:46 -0700
From:   kys@...hange.microsoft.com
To:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        devel@...uxdriverproject.org, olaf@...fle.de, apw@...onical.com,
        vkuznets@...hat.com, jasowang@...hat.com,
        leann.ogasawara@...onical.com, marcelo.cerri@...onical.com,
        sthemmin@...rosoft.com
Cc:     Dexuan Cui <decui@...rosoft.com>,
        "K . Y . Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>
Subject: [PATCH 2/5] vmbus: suppress uevents for hv_sock devices

From: Dexuan Cui <decui@...rosoft.com>

hv_sock driver is automatically loaded when an application creates an
AF_VSOCK socket, so we don't really need to trigger uevents to the user
space udevd.

And hv_sock devices can appear and disappear frequency, e.g. 100 per
second, so triggering the udevents can cause a high cpu utilization of
udevd, e.g. 30% on a 2-cpu virtual machine. So let's suppress the
uevents to avoid this.

Signed-off-by: Dexuan Cui <decui@...rosoft.com>
Cc: K. Y. Srinivasan <kys@...rosoft.com>
Cc: Haiyang Zhang <haiyangz@...rosoft.com>
Cc: Stephen Hemminger <sthemmin@...rosoft.com>
Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
---
 drivers/hv/vmbus_drv.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 43160a2eafe0..2c147702ce08 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1174,6 +1174,8 @@ int vmbus_device_register(struct hv_device *child_device_obj)
 	child_device_obj->device.parent = &hv_acpi_dev->dev;
 	child_device_obj->device.release = vmbus_device_release;
 
+	if (is_hvsock_channel(child_device_obj->channel))
+		dev_set_uevent_suppress(&child_device_obj->device, 1);
 	/*
 	 * Register with the LDM. This will kick off the driver/device
 	 * binding...which will eventually call vmbus_match() and vmbus_probe()
-- 
2.14.1