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| author |  Johan Hovold <johan+linaro@kernel.org>
| 2024-01-30 11:02:43 +0100 |
|---|---|---|
| committer |  Bjorn Helgaas <bhelgaas@google.com>
| 2024-01-31 09:03:51 -0600 |
| commit | 1e560864159d002b453da42bd2c13a1805515a20 (patch) | |
| tree | 3a6f7ecc33a0197caf4c4f4f3ff3bb8461636619 /drivers/pci/controller/dwc | |
| parent | Linux 6.8-rc1 (diff) | |
| download | linux-1e560864159d002b453da42bd2c13a1805515a20.tar.gz linux-1e560864159d002b453da42bd2c13a1805515a20.tar.bz2 linux-1e560864159d002b453da42bd2c13a1805515a20.zip | |
PCI/ASPM: Fix deadlock when enabling ASPM
A last minute revert in 6.7-final introduced a potential deadlock when
enabling ASPM during probe of Qualcomm PCIe controllers as reported by
lockdep:
============================================
WARNING: possible recursive locking detected
6.7.0 #40 Not tainted
--------------------------------------------
kworker/u16:5/90 is trying to acquire lock:
ffffacfa78ced000 (pci_bus_sem){++++}-{3:3}, at: pcie_aspm_pm_state_change+0x58/0xdc
but task is already holding lock:
ffffacfa78ced000 (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 ***
Call trace:
print_deadlock_bug+0x25c/0x348
__lock_acquire+0x10a4/0x2064
lock_acquire+0x1e8/0x318
down_read+0x60/0x184
pcie_aspm_pm_state_change+0x58/0xdc
pci_set_full_power_state+0xa8/0x114
pci_set_power_state+0xc4/0x120
qcom_pcie_enable_aspm+0x1c/0x3c [pcie_qcom]
pci_walk_bus+0x64/0xbc
qcom_pcie_host_post_init_2_7_0+0x28/0x34 [pcie_qcom]
The deadlock can easily be reproduced on machines like the Lenovo ThinkPad
X13s by adding a delay to increase the race window during asynchronous
probe where another thread can take a write lock.
Add a new pci_set_power_state_locked() and associated helper functions that
can be called with the PCI bus semaphore held to avoid taking the read lock
twice.
Link: https://lore.kernel.org/r/ZZu0qx2cmn7IwTyQ@hovoldconsulting.com
Link: https://lore.kernel.org/r/20240130100243.11011-1-johan+linaro@kernel.org
Fixes: f93e71aea6c6 ("Revert "PCI/ASPM: Remove pcie_aspm_pm_state_change()"")
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: <stable@vger.kernel.org> # 6.7
Diffstat (limited to 'drivers/pci/controller/dwc')
| -rw-r--r-- | drivers/pci/controller/dwc/pcie-qcom.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c index 10f2d0bb86be..2ce2a3bd932b 100644 --- a/drivers/pci/controller/dwc/pcie-qcom.c +++ b/drivers/pci/controller/dwc/pcie-qcom.c @@ -972,7 +972,7 @@ static int qcom_pcie_enable_aspm(struct pci_dev *pdev, void *userdata) * Downstream devices need to be in D0 state before enabling PCI PM * substates. */ - pci_set_power_state(pdev, PCI_D0); + pci_set_power_state_locked(pdev, PCI_D0); pci_enable_link_state_locked(pdev, PCIE_LINK_STATE_ALL); return 0; |