From: longli@linuxonhyperv.com
To: "K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Wei Liu <wei.liu@kernel.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Rob Herring <robh@kernel.org>,
Bjorn Helgaas <bhelgaas@google.com>,
linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Long Li <longli@microsoft.com>
Subject: [PATCH] PCI: hv: Fix a race condition when removing the device
Date: Mon, 19 Apr 2021 12:20:54 -0700 [thread overview]
Message-ID: <1618860054-928-1-git-send-email-longli@linuxonhyperv.com> (raw)
From: Long Li <longli@microsoft.com>
On removing the device, any work item (hv_pci_devices_present() or
hv_pci_eject_device()) scheduled on workqueue hbus->wq may still be running
and race with hv_pci_remove().
This can happen because the host may send PCI_EJECT or PCI_BUS_RELATIONS(2)
and decide to rescind the channel immediately after that.
Fix this by flushing/stopping the workqueue of hbus before doing hbus remove.
Signed-off-by: Long Li <longli@microsoft.com>
---
drivers/pci/controller/pci-hyperv.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 27a17a1e4a7c..116815404313 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -3305,6 +3305,17 @@ static int hv_pci_remove(struct hv_device *hdev)
hbus = hv_get_drvdata(hdev);
if (hbus->state == hv_pcibus_installed) {
+ tasklet_disable(&hdev->channel->callback_event);
+ hbus->state = hv_pcibus_removing;
+ tasklet_enable(&hdev->channel->callback_event);
+
+ flush_workqueue(hbus->wq);
+ /*
+ * At this point, no work is running or can be scheduled
+ * on hbus-wq. We can't race with hv_pci_devices_present()
+ * or hv_pci_eject_device(), it's safe to proceed.
+ */
+
/* Remove the bus from PCI's point of view. */
pci_lock_rescan_remove();
pci_stop_root_bus(hbus->pci_bus);
--
2.27.0
next reply other threads:[~2021-04-19 19:26 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-19 19:20 longli [this message]
2021-04-21 17:33 ` [PATCH] PCI: hv: Fix a race condition when removing the device Michael Kelley
2021-04-21 19:56 ` Long Li
2021-04-21 21:05 ` Michael Kelley
2021-04-22 2:31 ` Dexuan Cui
2021-04-22 3:57 ` Long Li
2021-04-22 4:19 ` 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=1618860054-928-1-git-send-email-longli@linuxonhyperv.com \
--to=longli@linuxonhyperv.com \
--cc=bhelgaas@google.com \
--cc=haiyangz@microsoft.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=robh@kernel.org \
--cc=sthemmin@microsoft.com \
--cc=wei.liu@kernel.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).