From: "H. Peter Anvin" <hpa@linux.intel.com>
To: Matt Fleming <matt@console-pimps.org>
Cc: linux-kernel@vger.kernel.org,
Matt Fleming <matt.fleming@linux.intel.com>,
Jan Beulich <JBeulich@novell.com>,
Matthew Garrett <mjg@redhat.com>, Tony Luck <tony.luck@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Alessandro Zummo <a.zummo@towertech.it>
Subject: Re: [PATCH] x86, efi: Don't recursively acquire rtc_lock
Date: Wed, 03 Aug 2011 16:12:31 -0700 [thread overview]
Message-ID: <4E39D5DF.6010104@linux.intel.com> (raw)
In-Reply-To: <1312405454-29386-1-git-send-email-matt@console-pimps.org>
On 08/03/2011 02:04 PM, Matt Fleming wrote:
> From: Matt Fleming <matt.fleming@linux.intel.com>
>
> A deadlock was introduced on x86 in commit ef68c8f87ed1 ("x86:
> Serialize EFI time accesses on rtc_lock") because efi_get_time() and
> friends can be called with rtc_lock already held by
> read_persistent_time(), e.g.
>
> timekeeping_init()
> read_persistent_clock() <-- acquire rtc_lock
> efi_get_time()
> phys_efi_get_time() <-- acquire rtc_lock <DEADLOCK>
>
> Move the locking up into the caller of efi.get_time() and provide some
> wrappers for use in other parts of the kernel instead of calling
> efi.get_time(), etc directly. This way we can hide the rtc_lock dance
> inside of arch/x86.
>
> Cc: Jan Beulich <JBeulich@novell.com>
> Cc: Matthew Garrett <mjg@redhat.com>
> Cc: "H. Peter Anvin" <hpa@linux.intel.com>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Fenghua Yu <fenghua.yu@intel.com>
> Cc: Alessandro Zummo <a.zummo@towertech.it>
> Signed-off-by: Matt Fleming <matt.fleming@linux.intel.com>
For the x86 footprint:
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
next prev parent reply other threads:[~2011-08-03 23:12 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-03 21:04 [PATCH] x86, efi: Don't recursively acquire rtc_lock Matt Fleming
2011-08-03 23:10 ` Tony Luck
2011-08-03 23:12 ` H. Peter Anvin [this message]
2011-08-04 10:22 ` john stultz
2011-08-04 10:36 ` Matt Fleming
2011-08-04 11:36 ` Matthew Garrett
-- strict thread matches above, loose matches on Subject: below --
2011-08-04 2:53 Jan Beulich
2011-08-04 3:04 ` Matthew Garrett
2011-08-04 9:33 ` Matt Fleming
2011-08-05 17:02 Jan Beulich
2011-08-05 17:04 Jan Beulich
2011-08-08 13:40 ` Matt Fleming
2011-08-08 14:07 ` Jan Beulich
2011-08-10 9:03 ` Ingo Molnar
2011-08-10 9:36 ` Jan Beulich
2011-08-10 9:51 ` Ingo Molnar
2011-08-10 13:12 ` Jan Beulich
2011-08-15 18:18 ` Matt Fleming
2011-08-16 6:22 ` Jan Beulich
2011-08-16 9:14 ` Matt Fleming
2011-08-30 15:45 ` Matthew Garrett
2011-08-30 16:07 ` Matt Fleming
2011-08-30 18:27 ` H. Peter Anvin
2011-08-10 14:55 ` Jan Beulich
2011-08-08 14:18 ` Avi Kivity
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