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* [Patch v2] PCI: hv: Fix sleep while in non-sleep context when removing child devices from the bus
@ 2021-08-30 23:13 longli
  2021-08-31 13:16 ` Wei Liu
  0 siblings, 1 reply; 3+ messages in thread
From: longli @ 2021-08-30 23:13 UTC (permalink / raw)
  To: linux-pci, linux-kernel, linux-hyperv
  Cc: Long Li, K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger,
	Wei Liu, Dexuan Cui, Lorenzo Pieralisi, Rob Herring,
	Krzysztof Wilczyński, Bjorn Helgaas, Michael Kelley

From: Long Li <longli@microsoft.com>

In hv_pci_bus_exit, the code is holding a spinlock while calling
pci_destroy_slot(), which takes a mutex.

This is not safe for spinlock. Fix this by moving the children to be
deleted to a list on the stack, and removing them after spinlock is
released.

Fixes: 94d22763207a ("PCI: hv: Fix a race condition when removing the device")

Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Rob Herring <robh@kernel.org>
Cc: "Krzysztof Wilczyński" <kw@linux.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Michael Kelley <mikelley@microsoft.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/linux-hyperv/20210823152130.GA21501@kili/
Signed-off-by: Long Li <longli@microsoft.com>
---
Changes in v2:
Made patch title more specific on what the patch does.
Added link to the original bug report.
Changed to list_for_each_entry_safe for iterating the removed list.

 drivers/pci/controller/pci-hyperv.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index a53bd8728d0d..fc1a29acadbb 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -3229,9 +3229,17 @@ static int hv_pci_bus_exit(struct hv_device *hdev, bool keep_devs)
 		return 0;
 
 	if (!keep_devs) {
-		/* Delete any children which might still exist. */
+		struct list_head removed;
+
+		/* Move all present children to the list on stack */
+		INIT_LIST_HEAD(&removed);
 		spin_lock_irqsave(&hbus->device_list_lock, flags);
-		list_for_each_entry_safe(hpdev, tmp, &hbus->children, list_entry) {
+		list_for_each_entry_safe(hpdev, tmp, &hbus->children, list_entry)
+			list_move_tail(&hpdev->list_entry, &removed);
+		spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+
+		/* Remove all children in the list */
+		list_for_each_entry_safe(hpdev, tmp, &removed, list_entry) {
 			list_del(&hpdev->list_entry);
 			if (hpdev->pci_slot)
 				pci_destroy_slot(hpdev->pci_slot);
@@ -3239,7 +3247,6 @@ static int hv_pci_bus_exit(struct hv_device *hdev, bool keep_devs)
 			put_pcichild(hpdev);
 			put_pcichild(hpdev);
 		}
-		spin_unlock_irqrestore(&hbus->device_list_lock, flags);
 	}
 
 	ret = hv_send_resources_released(hdev);
-- 
2.25.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [Patch v2] PCI: hv: Fix sleep while in non-sleep context when removing child devices from the bus
  2021-08-30 23:13 [Patch v2] PCI: hv: Fix sleep while in non-sleep context when removing child devices from the bus longli
@ 2021-08-31 13:16 ` Wei Liu
  2021-09-24  9:35   ` Wei Liu
  0 siblings, 1 reply; 3+ messages in thread
From: Wei Liu @ 2021-08-31 13:16 UTC (permalink / raw)
  To: longli
  Cc: linux-pci, linux-kernel, linux-hyperv, Long Li, K. Y. Srinivasan,
	Haiyang Zhang, Stephen Hemminger, Wei Liu, Dexuan Cui,
	Lorenzo Pieralisi, Rob Herring, Krzysztof Wilczyński,
	Bjorn Helgaas, Michael Kelley

On Mon, Aug 30, 2021 at 04:13:27PM -0700, longli@linuxonhyperv.com wrote:
> From: Long Li <longli@microsoft.com>
> 
> In hv_pci_bus_exit, the code is holding a spinlock while calling
> pci_destroy_slot(), which takes a mutex.
> 
> This is not safe for spinlock. Fix this by moving the children to be
> deleted to a list on the stack, and removing them after spinlock is
> released.
> 
> Fixes: 94d22763207a ("PCI: hv: Fix a race condition when removing the device")
> 
> Cc: "K. Y. Srinivasan" <kys@microsoft.com>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>
> Cc: Stephen Hemminger <sthemmin@microsoft.com>
> Cc: Wei Liu <wei.liu@kernel.org>
> Cc: Dexuan Cui <decui@microsoft.com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Rob Herring <robh@kernel.org>
> Cc: "Krzysztof Wilczyński" <kw@linux.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Michael Kelley <mikelley@microsoft.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Link: https://lore.kernel.org/linux-hyperv/20210823152130.GA21501@kili/
> Signed-off-by: Long Li <longli@microsoft.com>

Reviewed-by: Wei Liu <wei.liu@kernel.org>

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [Patch v2] PCI: hv: Fix sleep while in non-sleep context when removing child devices from the bus
  2021-08-31 13:16 ` Wei Liu
@ 2021-09-24  9:35   ` Wei Liu
  0 siblings, 0 replies; 3+ messages in thread
From: Wei Liu @ 2021-09-24  9:35 UTC (permalink / raw)
  To: longli
  Cc: linux-pci, linux-kernel, linux-hyperv, Long Li, K. Y. Srinivasan,
	Haiyang Zhang, Stephen Hemminger, Wei Liu, Dexuan Cui,
	Lorenzo Pieralisi, Rob Herring, Krzysztof Wilczyński,
	Bjorn Helgaas, Michael Kelley

On Tue, Aug 31, 2021 at 01:16:07PM +0000, Wei Liu wrote:
> On Mon, Aug 30, 2021 at 04:13:27PM -0700, longli@linuxonhyperv.com wrote:
> > From: Long Li <longli@microsoft.com>
> > 
> > In hv_pci_bus_exit, the code is holding a spinlock while calling
> > pci_destroy_slot(), which takes a mutex.
> > 
> > This is not safe for spinlock. Fix this by moving the children to be
> > deleted to a list on the stack, and removing them after spinlock is
> > released.
> > 
> > Fixes: 94d22763207a ("PCI: hv: Fix a race condition when removing the device")
> > 
> > Cc: "K. Y. Srinivasan" <kys@microsoft.com>
> > Cc: Haiyang Zhang <haiyangz@microsoft.com>
> > Cc: Stephen Hemminger <sthemmin@microsoft.com>
> > Cc: Wei Liu <wei.liu@kernel.org>
> > Cc: Dexuan Cui <decui@microsoft.com>
> > Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > Cc: Rob Herring <robh@kernel.org>
> > Cc: "Krzysztof Wilczyński" <kw@linux.com>
> > Cc: Bjorn Helgaas <bhelgaas@google.com>
> > Cc: Michael Kelley <mikelley@microsoft.com>
> > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > Link: https://lore.kernel.org/linux-hyperv/20210823152130.GA21501@kili/
> > Signed-off-by: Long Li <longli@microsoft.com>
> 
> Reviewed-by: Wei Liu <wei.liu@kernel.org>

Applied to hyperv-fixes.

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2021-09-24  9:35 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2021-08-30 23:13 [Patch v2] PCI: hv: Fix sleep while in non-sleep context when removing child devices from the bus longli
2021-08-31 13:16 ` Wei Liu
2021-09-24  9:35   ` Wei Liu

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