lkml.org 
[lkml]   [2015]   [Sep]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH] driver core: Ensure proper suspend/resume ordering
    From
    Date
    On 09/16/2015 04:28 AM, Rafael J. Wysocki wrote:
    > On Tuesday, September 15, 2015 03:18:19 PM Alan Stern wrote:
    >> On Tue, 15 Sep 2015, Thierry Reding wrote:
    >>
    >>>> There are a few things to watch out for. Since the dpm_list gets
    >>>> modified during system sleep transitions, we would have to make sure
    >>>> that nothing gets probed during those times. In principle, that's what
    >>>> the "prepare" stage is meant for, but there's still a race. As long as
    >>>> no other kernel thread (such as the deferred probing mechanism) tries
    >>>> to probe a device once everything has been frozen, we should be okay.
    >>>> But if not, there will be trouble -- after the ->prepare callback runs,
    >>>> the device is no longer on the dpm_list and so we don't want this patch
    >>>> to put it back on that list.
    >>>
    >>> Perhaps moving to the end of the list needs to be a little smarter. That
    >>> is it could check whether the device has been prepared for suspension or
    >>> not and only move when it hasn't?
    >>
    >> Maybe. But doesn't that mean it won't solve your problem completely?
    >>
    >>> Then again, shouldn't the core even prohibit new probes once the suspend
    >>> has been triggered? Sounds like asking for a lot of trouble if it didn't
    >>> ...
    >>
    >> The core prohibits new devices from being registered. It does not
    >> prohibit probes of existing devices, because they currently do not
    >> affect the dpm_list.

    Seems I missed smth, but I can't find the place in Kernel that prohibits
    creation of new devices during suspend.

    Could someone point me on, please?




    --
    regards,
    -grygorii


    \
     
     \ /
      Last update: 2015-09-16 16:01    [W:4.598 / U:0.788 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site