Hi Grygorii, On Thu, Dec 08, 2016 at 05:33:10PM -0600, Grygorii Strashko wrote: > From: "Strashko, Grygorii" <grygorii.strashko@xxxxxx> > > The below call chain generates "scheduling while atomic" backtrace and > causes system crash when Keystone 2 IRQ chip driver is used with RT-kernel: > > gic_handle_irq() > |-__handle_domain_irq() > |-generic_handle_irq() > |-keystone_irq_handler() > |-regmap_read() > |-regmap_lock_spinlock() > |-rt_spin_lock() > > The reason is that Keystone driver dispatches IRQ using chained IRQ handler > and accesses I/O memory through syscon->regmap(mmio) which is implemented > as fast_io regmap and uses regular spinlocks for synchronization, but > spinlocks transformed to rt_mutexes on RT. > > Hence, convert Keystone 2 IRQ driver to use generic irq handler instead of > chained IRQ handler. This way it will be compatible with RT kernel where it > will be forced thread IRQ handler while in non-RT kernel it still will be > executed in HW IRQ context. > > Cc: Suman Anna <s-anna@xxxxxx> > Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx> > --- > Hi, > > In general, there is an option to convert this driver to use nested threaded > irq handlers (this should not affect our current user of these irqs from > performance point of view), but that will affect on our current remoteproc and > UIO based drivers (including uio core) which do not expect to use threaded > irq and use request_irq(). These drivers and UIO core might require to be > updated to use threaded irqs and (or) request_any_context_irq(). > > Suman, what do you think? > > drivers/irqchip/irq-keystone.c | 28 +++++++++++++++++++--------- > 1 file changed, 19 insertions(+), 9 deletions(-) Applied to irqchip/urgent with Suman's Tested-by. thx, Jason. -- 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
