lkml.org 
[lkml]   [2010]   [Feb]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] sysfs: differentiate between locking links and non-links
    On Wed, Feb 10, 2010 at 10:25:21AM -0800, Eric W. Biederman wrote:
    > Tejun Heo <tj@kernel.org> writes:
    >
    > > On 02/10/2010 05:03 PM, Eric W. Biederman wrote:
    > >> Tejun Heo <tj@kernel.org> writes:
    > >>
    > >>> Hello,
    > >>>
    > >>> On 02/10/2010 11:08 AM, Américo Wang wrote:
    > >>>> This bug report is new for me. Recently we received lots of sysfs lockdep
    > >>>> warnings, I am working on a patch to fix all the bogus ones.
    > >>>>
    > >>>> However, this one is _not_ similar to the other cases, as you decribed.
    > >>>> This patch could fix the problem, but not a good fix, IMO. We need more
    > >>>> work in sysfs layer to fix this kind of things. I will take care of this.
    > >>>
    > >>> Can't we just give each s_active lock a separate class? Would that be
    > >>> too costly?
    > >>
    > >> When I asked the question earlier I was told that that locking classes
    > >> require static storage. Where would that static storage come from?
    > >
    > > Maybe I'm glossly misunderstanding it but wouldn't embedding struct
    > > lockdep_map into sysfs_node as in work_struct do the trick?
    >
    > In lockdep_init_map there is the following check:
    >
    > /*
    > * Sanity check, the lock-class key must be persistent:
    > */
    > if (!static_obj(key)) {
    > printk("BUG: key %p not in .data!\n", key);
    > DEBUG_LOCKS_WARN_ON(1);
    > return;
    > }
    >
    > It needs playing with but I think we can embed something in struct
    > attribute, and simply disallow dynamically allocated instances of
    > struct attribute.

    I think some code dynamically creates attributes today, as this has
    never been a restriction.

    So I don't know if this is going to work :(

    thanks,

    greg k-h
    --
    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: 2010-02-11 01:57    [W:0.024 / U:32.524 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site