On Wed, 2009-10-07 at 21:31 +0200, John Kacur wrote: > > On Wed, 7 Oct 2009, Sven-Thorsten Dietrich wrote: > > > On Wed, 2009-10-07 at 20:19 +0200, John Kacur wrote: > > > I've been staring at the BKL lock in cpuid_open, and I can't see what it > > > is protecting. However, I may have missed something - even something > > > obvious, so comments are welcome. > > > > I have been using this patch to first see if the BKL is being used > > simply as mutex, which would allow easier break-down. > > > > Sven > > > Cool! Seems like an excellent experiment. However this is a separate patch > from the one initially proposed in this thread. I'm willing to risk just > removing it in this case without any intermediary step. However, if anyone > points out to me why I'm a knuckle head and missed something obvious - I'll > listen. Otherwise, let's use your patch as a separate tactic to kill BKL. > Yes, I meant to send this out as RFC Monday, but got side-tracked with catch-up work, so you prompted me to just reply to your patch. I was also looking at the cycle_kernel_lock() call in arch/x86/kernel/microcode_core.c, which is not obvious to me. I converted that to cycle_kernel_mutex() using the patch I sent earlier, but have not had time to actually boot and test. In any case, I see bkl accesses all over various driver open() and ioctl() calls. I think that a number of these are safe to remove, as I still fail to understand why its necessary to take BKL during any driver open() routing. So if its fine for the cpuid_open() call, then I would assume its ok for others. Sven -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
