On Jan 03, 2024 / 17:55, Greg Kroah-Hartman wrote:
6.1-stable review patch. If anyone has any objections, please let me know.
From: Shin'ichiro Kawasaki shinichiro.kawasaki@wdc.com
commit b28ff7a7c3245d7f62acc20f15b4361292fe4117 upstream.
p2sb_bar() unhides P2SB device to get resources from the device. It guards the operation by locking pci_rescan_remove_lock so that parallel rescans do not find the P2SB device. However, this lock causes deadlock when PCI bus rescan is triggered by /sys/bus/pci/rescan. The rescan locks pci_rescan_remove_lock and probes PCI devices. When PCI devices call p2sb_bar() during probe, it locks pci_rescan_remove_lock again. Hence the deadlock.
To avoid the deadlock, do not lock pci_rescan_remove_lock in p2sb_bar(). Instead, do the lock at fs_initcall. Introduce p2sb_cache_resources() for fs_initcall which gets and caches the P2SB resources. At p2sb_bar(), refer the cache and return to the caller.
Suggested-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Fixes: 9745fb07474f ("platform/x86/intel: Add Primary to Sideband (P2SB) bridge support") Cc: stable@vger.kernel.org Signed-off-by: Shin'ichiro Kawasaki shinichiro.kawasaki@wdc.com Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Link: https://lore.kernel.org/linux-pci/6xb24fjmptxxn5js2fjrrddjae6twex5bjaftwqsua... Link: https://lore.kernel.org/r/20231229063912.2517922-2-shinichiro.kawasaki@wdc.c... Signed-off-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
Greg, please drop this patch from 6.1-stable for now. Unfortunately, one issue has got reported [*].
[*] https://lore.kernel.org/platform-driver-x86/CABq1_vjfyp_B-f4LAL6pg394bP6nDFy...