From: "Michael S. Tsirkin" <mst@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: xuyandong <xuyandong2@huawei.com>,
stable@vger.kernel.org, Yinghai Lu <yinghai@kernel.org>,
Jesse Barnes <jbarnes@virtuousgeek.org>,
Bjorn Helgaas <bhelgaas@google.com>,
linux-pci@vger.kernel.org
Subject: [PATCH] pci: avoid bridge feature re-probing on hotplug
Date: Mon, 10 Dec 2018 21:18:40 -0500 [thread overview]
Message-ID: <20181211021617.24072-1-mst@redhat.com> (raw)
commit 1f82de10d6 ("PCI/x86: don't assume prefetchable ranges are
64bit") added probing of bridge support for 64 bit memory
each time bridge is re-enumerated.
Unfortunately this probing is destructive if any device behind
the bridge is in use at this time.
There's no real need to re-probe the bridge features as the
regiters in question never change - detect that using
the memory flag being set and skip the probing.
Avoiding repeated calls to pci_bridge_check_ranges might be even nicer
would be a bigger patch and probably not appropriate on stable.
Reported-by: xuyandong <xuyandong2@huawei.com>
Cc: stable@vger.kernel.org
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
This issue has been reported on upstream Linux and Centos.
drivers/pci/setup-bus.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index ed960436df5e..7ab42f76579e 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -741,6 +741,13 @@ static void pci_bridge_check_ranges(struct pci_bus *bus)
struct resource *b_res;
b_res = &bridge->resource[PCI_BRIDGE_RESOURCES];
+
+ /* Don't re-check after this was called once already:
+ * important since bridge might be in use.
+ */
+ if (b_res[1].flags & IORESOURCE_MEM)
+ return;
+
b_res[1].flags |= IORESOURCE_MEM;
pci_read_config_word(bridge, PCI_IO_BASE, &io);
--
MST
next reply other threads:[~2018-12-11 2:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-11 2:18 Michael S. Tsirkin [this message]
2018-12-11 2:45 ` [PATCH] pci: avoid bridge feature re-probing on hotplug xuyandong
2018-12-11 4:11 ` Michael S. Tsirkin
2018-12-11 14:18 ` Bjorn Helgaas
2018-12-11 19:01 ` Michael S. Tsirkin
2018-12-16 19:38 ` Michael S. Tsirkin
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=20181211021617.24072-1-mst@redhat.com \
--to=mst@redhat.com \
--cc=bhelgaas@google.com \
--cc=jbarnes@virtuousgeek.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=stable@vger.kernel.org \
--cc=xuyandong2@huawei.com \
--cc=yinghai@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).