Messages in this thread |  | | | Subject | Re: [PATCH 01/12] Use mutex instead of semaphore in driver core | | From | Peter Zijlstra <> | | Date | Sun, 30 Dec 2007 13:13:51 +0100 |
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On Sat, 2007-12-29 at 22:42 -0800, David Brownell wrote: > On Saturday 29 December 2007, Alan Stern wrote:
> > There's no way to remove these, which means there's > > no way to prevent lockdep from issuing a warning. > > There may be no *efficient* way to do that. If it tracked > every lock individually these false alarms could go away; > but that would increase the overhead to create and destroy > such locks too.
No, tracking locks individually defeats the power of lockdep, that is warning of lock inversion before it actually happens. That really requires classes.
Annotating a tree requires grouping per level, and that isn't particularly hard (although I haven't yet tried it for the device tree - doing this conversion is still on my todo list). The hardest part of the device->sem conversion is the suspend/resume part, where it locks the whole tree and lockdep is limited in tracking held locks.
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