Messages in this thread | | | Date | Wed, 12 May 2010 23:39:12 +0400 | From | Anton Vorontsov <> | Subject | Re: [PATCH] Introduce {sysfs,device}_create_file_mode |
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On Wed, May 12, 2010 at 12:19:55PM -0700, Greg KH wrote: > On Wed, May 12, 2010 at 09:12:46PM +0200, Kay Sievers wrote: > > On Wed, May 12, 2010 at 21:08, Anton Vorontsov <cbouatmailru@gmail.com> wrote: > > > On Wed, May 12, 2010 at 11:38:06AM -0700, Greg KH wrote: > > >> On Wed, May 12, 2010 at 10:15:46PM +0400, Anton Vorontsov wrote: > > >> > We need to create attributes with different modes across devices. > > >> > We can do this by modifying attr.mode between device_create_file > > >> > invocations, but that is racy in case of globally defined attrs. > > >> > > > >> > Luckily, there's sysfs_add_file_mode() function that seems to do > > >> > exactly what we want, and if we use it, we don't need any locks > > >> > to avoid races. Though, it isn't exposed via device-drivers core > > >> > API. > > >> > > >> But you race the creation of the device notifying userspace, and then > > >> the file being created, right? > > > > > > Yep, you've raised that question once, like 3 years ago. :-) > > > > > > http://lkml.org/lkml/2007/4/11/452 > > > http://lkml.org/lkml/2007/4/12/144 > > > > > > In short: we can't use attr groups since the attributes creation > > > is conditional. And we especially don't want to use the attr groups > > > for attrs with different modes. But it's not a problem, because... > > > > Groups have a filter callback for every member, to decide if the > > attribute should be created or not. > > Yeah, that's how we solved that issue a long time ago :)
But not loud enough for us to notice. ;-)
> Can you please switch to using attribute groups now, so that userspace > doesn't have to handle 'change' events?
Yep.
Thanks,
-- Anton Vorontsov email: cbouatmailru@gmail.com irc://irc.freenode.net/bd2
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