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Johan Hovold 0f7908a016 PCI/ASPM: Fix deadlock when enabling ASPM 
commit 1e56086415 upstream.

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: f93e71aea6 ("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
[bhelgaas: backported to v6.1.y, which contains b9c370b61d ("Revert
 "PCI/ASPM: Remove pcie_aspm_pm_state_change()""), a backport of
 f93e71aea6.  This omits the drivers/pci/controller/dwc/pcie-qcom.c hunk
 that updates qcom_pcie_enable_aspm(), which was added by 9f4f3dfad8
 ("PCI: qcom: Enable ASPM for platforms supporting 1.9.0 ops"), which is not
 present in v6.1.87.]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2024-04-27 17:07:18 +02:00
..
acpi
…
asm-generic linux/init: remove __memexit* annotations 2024-02-23 09:12:38 +01:00
clocksource
…
crypto crypto: af_alg - Disallow multiple in-flight AIO requests 2024-01-25 15:27:21 -08:00
drm drm/probe-helper: warn about negative .get_modes() 2024-04-03 15:19:36 +02:00
dt-bindings clk: renesas: r8a779g0: Correct PFC/GPIO parent clocks 2024-03-26 18:20:48 -04:00
keys
…
kunit
…
kvm KVM: arm64: Fix host-programmed guest events in nVHE 2024-04-10 16:28:23 +02:00
linux PCI/ASPM: Fix deadlock when enabling ASPM 2024-04-27 17:07:18 +02:00
math-emu
…
media media: mc: Add num_links flag to media_pad 2024-04-03 15:19:25 +02:00
memory
…
misc
…
net net: dsa: introduce preferred_default_local_cpu_port and use on MT7530 2024-04-27 17:07:17 +02:00
pcmcia
…
ras
…
rdma
…
rv
…
scsi scsi: sd: usb_storage: uas: Access media prior to querying device properties 2024-04-13 13:05:24 +02:00
soc
…
sound
…
target
…
trace SUNRPC: Fix rpcgss_context trace event acceptor field 2024-04-27 17:07:04 +02:00
uapi PCI/DPC: Use FIELD_GET() 2024-04-27 17:07:11 +02:00
ufs
…
vdso
…
video
…
xen
…