On Fri, 29 Dec 2023, Shin'ichiro Kawasaki wrote: > 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. > > Link: https://lore.kernel.org/linux-pci/6xb24fjmptxxn5js2fjrrddjae6twex5bjaftwqsuawuqqqydx@7cl3uik5ef6j/ > Fixes: 9745fb07474f ("platform/x86/intel: Add Primary to Sideband (P2SB) bridge support") > Suggested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@xxxxxxx> Thanks for the update. I've replaced the commit in review-ilpo branch with this v5 patch 1/2. -- i.
