linux-kernel - [PATCH RFC 2/4] pci: don't disable msi/msix at shutdown

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Message-ID: <1426526415-13299-3-git-send-email-mst@redhat.com>
Date:	Mon, 16 Mar 2015 18:20:32 +0100
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
	Fam Zheng <famz@...hat.com>,
	Yinghai Lu <yhlu.kernel.send@...il.com>,
	Ulrich Obergfell <uobergfe@...hat.com>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: [PATCH RFC 2/4] pci: don't disable msi/msix at shutdown

This partially reverts commit d52877c7b1afb8c37ebe17e2005040b79cb618b0:
	"pci/irq: let pci_device_shutdown to call pci_msi_shutdown v2"

It's un-necessary now that we disable msi at start, and it actually
turns out to cause problems: some device drivers don't register a level
interrupt handler when they detect msi/msix capability, switching off
msi while device is going causes device to assert a level interrupt
which is never de-asserted, causing a kernel hang.

In particular, this was observed with virtio.

Cc: Yinghai Lu <yhlu.kernel.send@...il.com>
Cc: Ulrich Obergfell <uobergfe@...hat.com>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Reported-by: Fam Zheng <famz@...hat.com>
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---
 drivers/pci/pci-driver.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index dac6d47..4746f93 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -456,8 +456,6 @@ static void pci_device_shutdown(struct device *dev)
 
 	if (drv && drv->shutdown)
 		drv->shutdown(pci_dev);
-	pci_msi_shutdown(pci_dev);
-	pci_msix_shutdown(pci_dev);
 
 #ifdef CONFIG_KEXEC
 	/*
-- 
MST

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