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

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Date:   Wed, 16 Aug 2017 03:39:17 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>
CC:     KY Srinivasan <kys@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "olaf@...fle.de" <olaf@...fle.de>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "apw@...onical.com" <apw@...onical.com>,
        Andy Lutomirski <luto@...nel.org>,
        "marcelo.cerri@...onical.com" <marcelo.cerri@...onical.com>,
        "leann.ogasawara@...onical.com" <leann.ogasawara@...onical.com>,
        "Rolf Neugebauer" <rolf.neugebauer@...ker.com>,
        'Marcelo Cerri' <marcelo.cerri@...onical.com>
Subject: [PATCH] vmbus: suppress uevents for hv_sock devices


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>
---
 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 ed84e96..a0cf592 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1171,6 +1171,8 @@ 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()
-- 
2.7.4