linux-kernel - [PATCH] Drivers: hv: vmbus: do not mark HV_PCIE as perf

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Date:   Sat, 3 Mar 2018 00:22:19 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        KY Srinivasan <kys@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "driverdev-devel@...uxdriverproject.org" 
        <driverdev-devel@...uxdriverproject.org>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "apw@...onical.com" <apw@...onical.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "marcelo.cerri@...onical.com" <marcelo.cerri@...onical.com>,
        Dexuan Cui <decui@...rosoft.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: [PATCH] Drivers: hv: vmbus: do not mark HV_PCIE as perf_device

The pci-hyperv driver's channel callback hv_pci_onchannelcallback() is not
really a hot path, so we don't need to mark it as a perf_device, meaning
with this patch all HV_PCIE channels' target_cpu will be CPU0.

This patch can help to avoid a potential ABBA deadlock in the busy loop
of Hyper-V PCI driver's hv_compose_msi_msg().

Signed-off-by: Dexuan Cui <decui@...rosoft.com>
Cc: stable@...r.kernel.org
Cc: Stephen Hemminger <sthemmin@...rosoft.com>
Cc: K. Y. Srinivasan <kys@...rosoft.com>
---
 drivers/hv/channel_mgmt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index c21020b69114..55ee5e87073a 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -71,7 +71,7 @@ static const struct vmbus_device vmbus_devs[] = {
 	/* PCIE */
 	{ .dev_type = HV_PCIE,
 	  HV_PCIE_GUID,
-	  .perf_device = true,
+	  .perf_device = false,
 	},
 
 	/* Synthetic Frame Buffer */
-- 
2.7.4