From: Wei Liu <wei.liu@kernel.org>
To: longli@linuxonhyperv.com
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-hyperv@vger.kernel.org, "Long Li" <longli@microsoft.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
"Haiyang Zhang" <haiyangz@microsoft.com>,
"Stephen Hemminger" <sthemmin@microsoft.com>,
"Wei Liu" <wei.liu@kernel.org>,
"Dexuan Cui" <decui@microsoft.com>,
"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
"Rob Herring" <robh@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Michael Kelley" <mikelley@microsoft.com>,
"Dan Carpenter" <dan.carpenter@oracle.com>
Subject: Re: [PATCH] PCI: hv: Fix a bug on removing child devices on the bus
Date: Tue, 24 Aug 2021 11:02:08 +0000 [thread overview]
Message-ID: <20210824110208.xd57oqm5rii4rr4n@liuwe-devbox-debian-v2> (raw)
In-Reply-To: <1629789620-11049-1-git-send-email-longli@linuxonhyperv.com>
On Tue, Aug 24, 2021 at 12:20:20AM -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>
> Cc: Dan Carpenter <dan.carpenter@oracle.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Long Li <longli@microsoft.com>
> ---
> drivers/pci/controller/pci-hyperv.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index a53bd8728d0d..d4f3cce18957 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -3220,6 +3220,7 @@ static int hv_pci_bus_exit(struct hv_device *hdev, bool keep_devs)
> struct hv_pci_dev *hpdev, *tmp;
> unsigned long flags;
> int ret;
> + struct list_head removed;
This can be moved to where it is needed -- the if(!keep_dev) branch --
to limit its scope.
>
> /*
> * After the host sends the RESCIND_CHANNEL message, it doesn't
> @@ -3229,9 +3230,18 @@ 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. */
> + INIT_LIST_HEAD(&removed);
> +
> + /* Move all present children to the list on stack */
> 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 */
> + while (!list_empty(&removed)) {
> + hpdev = list_first_entry(&removed, struct hv_pci_dev,
> + list_entry);
list_for_each_entry_safe can also be used here, right?
Wei.
> list_del(&hpdev->list_entry);
> if (hpdev->pci_slot)
> pci_destroy_slot(hpdev->pci_slot);
> @@ -3239,7 +3249,6 @@ 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
>
next prev parent reply other threads:[~2021-08-24 11:02 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-24 7:20 [PATCH] PCI: hv: Fix a bug on removing child devices on the bus longli
2021-08-24 11:02 ` Wei Liu [this message]
2021-08-24 17:28 ` Long Li
2021-08-25 19:11 ` Michael Kelley
2021-08-25 20:25 ` Long Li
2021-08-26 16:50 ` Michael Kelley
2021-08-26 19:41 ` Wei Liu
2021-08-26 20:09 ` Long Li
2021-08-26 20:15 ` Wei Liu
2021-08-26 20:20 ` Long Li
2021-08-25 20:32 ` Rob Herring
2021-08-24 12:25 ` Bjorn Helgaas
2021-08-24 17:30 ` Long Li
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