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f352ce9992
The qcom_pcie_enable_aspm() helper is called from pci_walk_bus() during
host init to enable ASPM.
Since pci_walk_bus() already holds a pci_bus_sem read lock, use
pci_enable_link_state_locked() to enable link states in order to avoid a
potential deadlock (e.g. in case someone takes a write lock before
reacquiring the read lock).
This issue was reported by lockdep:
============================================
WARNING: possible recursive locking detected
6.7.0-rc1 #4 Not tainted
--------------------------------------------
kworker/u16:6/147 is trying to acquire lock:
ffffbf3ff9d2cfa0 (pci_bus_sem){++++}-{3:3}, at: pci_enable_link_state+0x74/0x1e8
but task is already holding lock:
ffffbf3ff9d2cfa0 (pci_bus_sem){++++}-{3:3}, at: pci_walk_bus+0x34/0xbc
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(pci_bus_sem);
lock(pci_bus_sem);
*** DEADLOCK ***
Fixes: 9f4f3dfad8 ("PCI: qcom: Enable ASPM for platforms supporting 1.9.0 ops")
Link: https://lore.kernel.org/r/20231128081512.19387-4-johan+linaro@kernel.org
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
[bhelgaas: add "potential" in subject since the deadlock has only been
reported by lockdep, include helper name in commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Linux kernel
============
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In order to build the documentation, use ``make htmldocs`` or
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There are various text files in the Documentation/ subdirectory,
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Please read the Documentation/process/changes.rst file, as it contains the
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the problems which may result by upgrading your kernel.