* Patch "PCI: Avoid possible deadlock on pci_lock and p->pi_lock" has been added to the 4.9-stable tree
@ 2017-11-06 9:11 gregkh
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From: gregkh @ 2017-11-06 9:11 UTC (permalink / raw)
To: bhelgaas, alexander.levin, gregkh; +Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
PCI: Avoid possible deadlock on pci_lock and p->pi_lock
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pci-avoid-possible-deadlock-on-pci_lock-and-p-pi_lock.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From foo@baz Mon Nov 6 10:07:36 CET 2017
From: Bjorn Helgaas <bhelgaas@google.com>
Date: Sat, 7 Oct 2017 22:37:34 +0000
Subject: PCI: Avoid possible deadlock on pci_lock and p->pi_lock
From: Bjorn Helgaas <bhelgaas@google.com>
[ Upstream commit cdcb33f9824429a926b971bf041a6cec238f91ff ]
pci_lock is an IRQ-safe spinlock that protects all accesses to PCI
configuration space (see PCI_OP_READ() and PCI_OP_WRITE() in pci/access.c).
The pci_cfg_access_unlock() path acquires pci_lock, then p->pi_lock (inside
wake_up_all()). According to lockdep, there is a possible path involving
snbep_uncore_pci_read_counter() that could acquire them in the reverse
order: acquiring p->pi_lock, then pci_lock, which could result in a
deadlock. Lockdep details are in the bugzilla below.
Avoid the possible deadlock by dropping pci_lock before waking up any
config access waiters.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=192901
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/pci/access.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -672,8 +672,9 @@ void pci_cfg_access_unlock(struct pci_de
WARN_ON(!dev->block_cfg_access);
dev->block_cfg_access = 0;
- wake_up_all(&pci_cfg_wait);
raw_spin_unlock_irqrestore(&pci_lock, flags);
+
+ wake_up_all(&pci_cfg_wait);
}
EXPORT_SYMBOL_GPL(pci_cfg_access_unlock);
Patches currently in stable-queue which might be from bhelgaas@google.com are
queue-4.9/pci-msi-return-failure-when-msix_setup_entries-fails.patch
queue-4.9/pci-avoid-possible-deadlock-on-pci_lock-and-p-pi_lock.patch
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2017-11-06 9:11 Patch "PCI: Avoid possible deadlock on pci_lock and p->pi_lock" has been added to the 4.9-stable tree gregkh
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