On Mon, Nov 08, 2010 at 04:28:54PM +0200, Andriy Gapon wrote: > on 08/11/2010 16:22 Nathan Whitehorn said the following: > > > > The other issue is that this can be a legal thing to do. If you have taken > > care to > > wire the userland buffers ahead of time, there is no problem copying > > copyin()/copyout() with sleepable locks held. The sysctl code does this. As > > such, > > you can't check for problems by panicing if sleepable locks are held. > > Nathan, > > very good point, thank you. > BTW, perhaps drm should be doing the same? > It seems that there are quite a few copyin/copyout calls (disguised with > macros) > in e.g. sys/dev/drm/radeon_state.c and likely all of them are under dev_lock. > So it would be painful to add unlock+lock around each such call. This would be a DoS, due to the size of the buffers.
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