LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: longli@linuxonhyperv.com
To: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-hyperv@vger.kernel.org
Cc: "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: [PATCH] PCI: hv: Fix a bug on removing child devices on the bus
Date: Tue, 24 Aug 2021 00:20:20 -0700	[thread overview]
Message-ID: <1629789620-11049-1-git-send-email-longli@linuxonhyperv.com> (raw)

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;
 
 	/*
 	 * 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_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


             reply	other threads:[~2021-08-24  7:20 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-24  7:20 longli [this message]
2021-08-24 11:02 ` Wei Liu
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1629789620-11049-1-git-send-email-longli@linuxonhyperv.com \
    --to=longli@linuxonhyperv.com \
    --cc=bhelgaas@google.com \
    --cc=dan.carpenter@oracle.com \
    --cc=decui@microsoft.com \
    --cc=haiyangz@microsoft.com \
    --cc=kw@linux.com \
    --cc=kys@microsoft.com \
    --cc=linux-hyperv@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=longli@microsoft.com \
    --cc=lorenzo.pieralisi@arm.com \
    --cc=mikelley@microsoft.com \
    --cc=robh@kernel.org \
    --cc=sthemmin@microsoft.com \
    --cc=wei.liu@kernel.org \
    --subject='Re: [PATCH] PCI: hv: Fix a bug on removing child devices on the bus' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).