Re: [PATCH v5 1/2] platform/x86: p2sb: Allow p2sb_bar() calls during PCI device probe

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

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@linux.intel.com>
> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>

Thanks for the update. I've replaced the commit in review-ilpo branch with 
this v5 patch 1/2.

-- 
 i.