On Wed, Jul 02, 2014 at 12:59:04PM +0200, Tomasz Figa wrote: > Hi All, > > While testing linux-next (next-20140625) on Exynos4412-based TRATS2 > board, from time to time I hit a deadlock between clk_disable_unused() > of Common Clock Framework and parallel clk_prepare() from s3c24xx-i2c > driver. This is pretty sad. The Linux kernel has quite a range of truely excellent debugging tools which can be built in, but it seems many developers don't enable them. The important one here is lockdep (which I notice isn't on in your kernel.) Lockdep is a static lock checker - it tracks the dependencies and contexts between various locks and can report whether deadlock is possible without having to run into the deadlock. It is /highly/ recommended that all developers should run their changes through a kernel with this feature on before submitting them upstream - see Documentation/SubmitChecklist point 15. It can really catch these things before the patch is even submitted... The recommendation is that if you're doing kernel development, always have lockdep enabled. If you want to do performance checking, then obviously it has an impact on that, so turn it off to do that, but remember to turn it back on before you do further development. -- FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly improving, and getting towards what was expected from it. -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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