Re: [PATCH] nvme: pci: Fix NULL dereference when resetting NVMe SSD

From	Christoph Hellwig <hch@lst.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] nvme: pci: Fix NULL dereference when resetting NVMe SSD
Date	2017-05-22 18:10 +0200
Message-ID	<tJY4a-7To-11@gated-at.bofh.it> (permalink)
References	<tJgZb-4S9-9@gated-at.bofh.it> <tJsnD-47k-1@gated-at.bofh.it> <tJXKO-7v6-17@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Mon, May 22, 2017 at 06:38:29PM +0300, Rakesh Pandit wrote:
> Just got to use the using the test box again and you are right that
> nvme_remove_dead_ctrl_work is getting called just before the NULL
> pointer dereference.
> 
> Here call trace to nvme_timeout which results in eventually call to
> nvme_reset when it wants to reset the controller (which races with
> ->reset_notify from PCI layer):

Does the patch below fix the issue for you?

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b01bd5bba8e6..f8c15e2719c4 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4275,11 +4275,13 @@ int pci_reset_function(struct pci_dev *dev)
 	if (rc)
 		return rc;
 
+	device_lock(&dev->dev);
 	pci_dev_save_and_disable(dev);
 
-	rc = pci_dev_reset(dev, 0);
+	rc = __pci_dev_reset(dev, 0);
 
 	pci_dev_restore(dev);
+	device_unlock(&dev->dev);
 
 	return rc;
 }

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[PATCH] nvme: pci: Fix NULL dereference when resetting NVMe SSD Rakesh Pandit <rakesh@tuxera.com> - 2017-05-20 20:10 +0200
  Re: [PATCH] nvme: pci: Fix NULL dereference when resetting NVMe SSD Christoph Hellwig <hch@lst.de> - 2017-05-21 08:20 +0200
    Re: [PATCH] nvme: pci: Fix NULL dereference when resetting NVMe SSD Rakesh Pandit <rakesh@tuxera.com> - 2017-05-22 17:50 +0200
      Re: [PATCH] nvme: pci: Fix NULL dereference when resetting NVMe SSD Christoph Hellwig <hch@lst.de> - 2017-05-22 18:10 +0200
        Re: [PATCH] nvme: pci: Fix NULL dereference when resetting NVMe SSD Rakesh Pandit <rakesh@tuxera.com> - 2017-05-22 22:20 +0200
      Re: [PATCH] nvme: pci: Fix NULL dereference when resetting NVMe SSD Christoph Hellwig <hch@lst.de> - 2017-05-22 18:10 +0200

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