On Fri, 2 May 2014 15:09:14 -0700 John Stultz <john.stu...@linaro.org> wrote:
> Recently, Jiri pointed out a potential deadlock when calling printk > while holding the timekeeping seqlock. > > Annoyingly, the seqlock lockdep enablement doesn't catch this, as > printk disables lockdep. > > When looking for possible solutions, one idea was to use a local buffer > and defer the printk to later. Ends up there is already similar > functionality in printk_sched() to avoid similar style deadlocks w/ > the scheduler. > > Thus this patchset (based on next/akpm) renames printk_sched to > printk_deferred and then moves the affected timekeeping printks to make > use of it. > > There were some points in the discussion between Jan and Peter that > made it seem that there may still be problems lurking in the console > layer, and I'm not sure I fully understand their point, so this solution > may be incomplete. > > Additionally, the same issue likely affects any WARN_ONs as well, but > I wanted to get some thoughts on this approach before trying to remove > or convert affected WARN_ONS. > > Your thoughts and feedback are greatly appreciated! All look pretty simple and sane to me. printk is a crazy hotspot lately but this patchset looks like it won't get singed. Would "printk_deferred_once" be more logical than "printk_once_deferred"? Think so. It's (((printk(deferred(once))), not (((printk(once(deferred))). Why do I see a pr_emerg_once_deferred() in my future? -- 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/
