On Tue, 2 Jul 2013, James Hogan wrote: > kick_handler() doesn't have an irq_enter/exit pair, but it's used for > handling SMP IPIs which require work to be done in softirqs, which are > invoked from irq_exit() when the hard irq nest count reaches 0. > > The scheduler_ipi() callback in the IPI handler calls irq_enter/exit > itself, but this is inside kick_handler()'s spin lock critical section, > so if an invoked softirq issues an IPI the kick_handler() will be > re-entered on the same CPU and will deadlock. > > This is easily fixed by adding the missing irq_enter/exit to > kick_handler() so that the hard irq nest count doesn't reach 0 until > after the spin lock has been released. > > Ideally the spin lock protected handler list will also be replaced by a > lockless RCU protected list since it is certainly mostly read. That can > be done in a later change though. > > Signed-off-by: James Hogan <james.ho...@imgtec.com>
Acked-by: Thomas Gleixner <t...@linutronix.de> -- 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/
