From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Alex Williamson <alex.williamson@redhat.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Sinan Kaya <okaya@kernel.org>, Sasha Levin <sashal@kernel.org>,
linux-pci@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 236/671] PCI: Fix "try" semantics of bus and slot reset
Date: Thu, 16 Jan 2020 11:52:25 -0500 [thread overview]
Message-ID: <20200116165940.10720-119-sashal@kernel.org> (raw)
In-Reply-To: <20200116165940.10720-1-sashal@kernel.org>
From: Alex Williamson <alex.williamson@redhat.com>
[ Upstream commit ddefc033eecf23f1e8b81d0663c5db965adf5516 ]
The commit referenced below introduced device locking around save and
restore of state for each device during a PCI bus "try" reset, making it
decidely non-"try" and prone to deadlock in the event that a device is
already locked. Restore __pci_reset_bus() and __pci_reset_slot() to their
advertised locking semantics by pushing the save and restore functions into
the branch where the entire tree is already locked. Extend the helper
function names with "_locked" and update the comment to reflect this
calling requirement.
Fixes: b014e96d1abb ("PCI: Protect pci_error_handlers->reset_notify() usage with device_lock()")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Sinan Kaya <okaya@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pci/pci.c | 54 +++++++++++++++++++++++------------------------
1 file changed, 26 insertions(+), 28 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index c9f51fc24563..57a87a001b4f 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5039,39 +5039,42 @@ static int pci_slot_trylock(struct pci_slot *slot)
return 0;
}
-/* Save and disable devices from the top of the tree down */
-static void pci_bus_save_and_disable(struct pci_bus *bus)
+/*
+ * Save and disable devices from the top of the tree down while holding
+ * the @dev mutex lock for the entire tree.
+ */
+static void pci_bus_save_and_disable_locked(struct pci_bus *bus)
{
struct pci_dev *dev;
list_for_each_entry(dev, &bus->devices, bus_list) {
- pci_dev_lock(dev);
pci_dev_save_and_disable(dev);
- pci_dev_unlock(dev);
if (dev->subordinate)
- pci_bus_save_and_disable(dev->subordinate);
+ pci_bus_save_and_disable_locked(dev->subordinate);
}
}
/*
- * Restore devices from top of the tree down - parent bridges need to be
- * restored before we can get to subordinate devices.
+ * Restore devices from top of the tree down while holding @dev mutex lock
+ * for the entire tree. Parent bridges need to be restored before we can
+ * get to subordinate devices.
*/
-static void pci_bus_restore(struct pci_bus *bus)
+static void pci_bus_restore_locked(struct pci_bus *bus)
{
struct pci_dev *dev;
list_for_each_entry(dev, &bus->devices, bus_list) {
- pci_dev_lock(dev);
pci_dev_restore(dev);
- pci_dev_unlock(dev);
if (dev->subordinate)
- pci_bus_restore(dev->subordinate);
+ pci_bus_restore_locked(dev->subordinate);
}
}
-/* Save and disable devices from the top of the tree down */
-static void pci_slot_save_and_disable(struct pci_slot *slot)
+/*
+ * Save and disable devices from the top of the tree down while holding
+ * the @dev mutex lock for the entire tree.
+ */
+static void pci_slot_save_and_disable_locked(struct pci_slot *slot)
{
struct pci_dev *dev;
@@ -5080,26 +5083,25 @@ static void pci_slot_save_and_disable(struct pci_slot *slot)
continue;
pci_dev_save_and_disable(dev);
if (dev->subordinate)
- pci_bus_save_and_disable(dev->subordinate);
+ pci_bus_save_and_disable_locked(dev->subordinate);
}
}
/*
- * Restore devices from top of the tree down - parent bridges need to be
- * restored before we can get to subordinate devices.
+ * Restore devices from top of the tree down while holding @dev mutex lock
+ * for the entire tree. Parent bridges need to be restored before we can
+ * get to subordinate devices.
*/
-static void pci_slot_restore(struct pci_slot *slot)
+static void pci_slot_restore_locked(struct pci_slot *slot)
{
struct pci_dev *dev;
list_for_each_entry(dev, &slot->bus->devices, bus_list) {
if (!dev->slot || dev->slot != slot)
continue;
- pci_dev_lock(dev);
pci_dev_restore(dev);
- pci_dev_unlock(dev);
if (dev->subordinate)
- pci_bus_restore(dev->subordinate);
+ pci_bus_restore_locked(dev->subordinate);
}
}
@@ -5158,17 +5160,15 @@ static int __pci_reset_slot(struct pci_slot *slot)
if (rc)
return rc;
- pci_slot_save_and_disable(slot);
-
if (pci_slot_trylock(slot)) {
+ pci_slot_save_and_disable_locked(slot);
might_sleep();
rc = pci_reset_hotplug_slot(slot->hotplug, 0);
+ pci_slot_restore_locked(slot);
pci_slot_unlock(slot);
} else
rc = -EAGAIN;
- pci_slot_restore(slot);
-
return rc;
}
@@ -5254,17 +5254,15 @@ static int __pci_reset_bus(struct pci_bus *bus)
if (rc)
return rc;
- pci_bus_save_and_disable(bus);
-
if (pci_bus_trylock(bus)) {
+ pci_bus_save_and_disable_locked(bus);
might_sleep();
rc = pci_bridge_secondary_bus_reset(bus->self);
+ pci_bus_restore_locked(bus);
pci_bus_unlock(bus);
} else
rc = -EAGAIN;
- pci_bus_restore(bus);
-
return rc;
}
--
2.20.1
prev parent reply other threads:[~2020-01-16 17:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200116165940.10720-1-sashal@kernel.org>
2020-01-16 16:51 ` [PATCH AUTOSEL 4.19 172/671] ntb_hw_switchtec: debug print 64bit aligned crosslink BAR Numbers Sasha Levin
2020-01-16 16:51 ` [PATCH AUTOSEL 4.19 173/671] ntb_hw_switchtec: NT req id mapping table register entry number should be 512 Sasha Levin
2020-01-16 16:51 ` [PATCH AUTOSEL 4.19 180/671] PCI: endpoint: functions: Use memcpy_fromio()/memcpy_toio() Sasha Levin
2020-01-16 16:52 ` Sasha Levin [this message]
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=20200116165940.10720-119-sashal@kernel.org \
--to=sashal@kernel.org \
--cc=alex.williamson@redhat.com \
--cc=bhelgaas@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=okaya@kernel.org \
--cc=stable@vger.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).