On Sat, Jul 21, 2012 at 01:08:55PM -0300, Henrique de Moraes Holschuh wrote: > On Sat, 21 Jul 2012, Colin Cross wrote: > > The delay_on and delay_off files could easily override the values from > > the trigger. > > > > Sending a KOBJ_CHANGE uevent is not a great solution, it's still > > horribly racy in userspace. This script would never work reliably: > > echo timer > trigger > > echo 1000 > delay_on > > echo 1000 > delay_off > > echo 255 > brightness > > Yes, and the proper fix is to instead use a fully async userspace based on > uevent callbacks. Nasty as all hell. Or the quick fix, which is to wait > for the system to settle after every sysfs operation that could create new > sysfs nodes. > > You could make sure that (1) no sysfs operation will return control to > userspace until it is complete, so you'd have all new sysfs nodes available > at the time the first echo returns [I believe it already works like that],
Yes it does, what's the problem here? > and (2) either enhance sysfs to create nodes with the desired ownership and > permissions >From the kernel, you can also do this today, if you know it's "safe" for users to read/write them. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
