On Mon, Aug 17, 2015 at 3:03 PM, Mika Westerberg <[email protected]> wrote:
> The Intel Baytrail pinctrl driver implements irqchip callbacks which are > called with desc->lock raw_spinlock held. In mainline this is fine because > spinlock resolves to raw_spinlock. However, running the same code in -rt we > get: > > BUG: sleeping function called from invalid context at > kernel/locking/rtmutex.c:917 > in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/0 > Preemption disabled at:[<ffffffff81092e9f>] cpu_startup_entry+0x17f/0x480 > > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.1.5-rt5 #13 > ... > Call Trace: > <IRQ> [<ffffffff816283c6>] dump_stack+0x4a/0x61 > [<ffffffff81077e17>] ___might_sleep+0xe7/0x170 > [<ffffffff8162d6cf>] rt_spin_lock+0x1f/0x50 > [<ffffffff812e3b88>] byt_gpio_clear_triggering+0x38/0x60 > [<ffffffff812e3bc1>] byt_irq_mask+0x11/0x20 > [<ffffffff810a7013>] handle_level_irq+0x83/0x150 > [<ffffffff810a3457>] generic_handle_irq+0x27/0x40 > [<ffffffff812e3a5f>] byt_gpio_irq_handler+0x7f/0xc0 > [<ffffffff810050aa>] handle_irq+0xaa/0x190 > ... > > This is because in -rt spinlocks are preemptible so taking the driver > private spinlock in irqchip callbacks causes might_sleep() to trigger. > > In order to keep -rt happy but at the same time make sure that register > accesses get serialized, convert the driver to use raw_spinlock instead. > > Also shorten the critical section a bit in few places. > > Suggested-by: Linus Walleij <[email protected]> > Signed-off-by: Mika Westerberg <[email protected]> Awesome job Mika, patch applied. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
