From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Cc: platform-driver-x86@vger.kernel.org,
"Hans de Goede" <hdegoede@redhat.com>,
"Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>,
"Lukas Wunner" <lukas@wunner.de>,
linux-pci@vger.kernel.org, linux-i2c@vger.kernel.org
Subject: Re: [PATCH v4] platform/x86: p2sb: Allow p2sb_bar() calls during PCI device probe
Date: Wed, 27 Dec 2023 18:47:56 +0200 [thread overview]
Message-ID: <ZYxVPCA4mu3vVLqt@smile.fi.intel.com> (raw)
In-Reply-To: <20231227072049.2281764-1-shinichiro.kawasaki@wdc.com>
On Wed, Dec 27, 2023 at 04:20:49PM +0900, 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.
As per v3 discussion:
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2023-12-27 16:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-27 7:20 [PATCH v4] platform/x86: p2sb: Allow p2sb_bar() calls during PCI device probe Shin'ichiro Kawasaki
2023-12-27 16:47 ` Andy Shevchenko [this message]
2023-12-27 18:32 ` Ilpo Järvinen
2023-12-28 15:47 ` Ilpo Järvinen
2023-12-29 1:38 ` Shinichiro Kawasaki
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