lkml.org 
[lkml]   [2010]   [Feb]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH] sysfs: differentiate between locking links and non-links
From
On Wed, Feb 10, 2010 at 9:21 AM, David Rientjes <rientjes@google.com> wrote:
> On Wed, 10 Feb 2010, Neil Brown wrote:
>
>> commit 2e502cfe444b68f6ef6b8b2abe83b6112564095b
>> Author: NeilBrown <neilb@suse.de>
>> Date:   Wed Feb 10 09:43:45 2010 +1100
>>
>>     sysfs: differentiate  between locking links and non-links for sysfs
>>
>>     symlinks and non-symlink is sysfs are very different.
>>     A symlink can never be locked (active) while an attribute
>>     modification routine is running.  So removing symlink from an
>>     attribute 'store' routine should be permitted without any lockdep
>>     warnings.
>>
>>     So split the lockdep context for 's_active' in two, one for symlinks
>>     and other for everything else.
>>
>
> What happens for hard links such as writing to
> /sys/devices/block/xxx/queue/scheduler to change an I/O scheduler which
> requires sd->dep_map and sd->parent->dep_map in sysfs_get_active_two() to
> pin both?  The call to kobject_del() invokes the destruction that also
> requires sd->dep_map in sysfs_deactivate() because of the s_active lockdep
> annotation.
>

This is not related with Neil's case at all.

The I/O scheduler switch case should be a bogus, I am working on
it. We have more similar cases of cpu hotplug. Trust me, I am working
on a fix to all of them, this is not as easy as you may think about.

Thanks.
--
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: 2010-02-10 02:59    [W:0.120 / U:0.308 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site