lkml.org 
[lkml]   [2011]   [Aug]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH] x86, efi: Don't recursively acquire rtc_lock
From
On Wed, Aug 3, 2011 at 2:04 PM, Matt Fleming <matt@console-pimps.org> 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.

Sorry if this should be obvious, but is there a reason your not using
your own internal lock for serializing the efi bits rather then using
the rtc_lock?

thanks
-john
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2011-08-04 12:25    [W:4.484 / U:0.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site