From cdd16365b0bd7c0cd19e2cc768b6bdc8021f32c3 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 20 Jun 2017 01:37:19 +0200 Subject: [PATCH] genirq: Provide irq_fixup_move_pending() If an CPU goes offline, the interrupts are migrated away, but a eventually pending interrupt move, which has not yet been made effective is kept pending even if the outgoing CPU is the sole target of the pending affinity mask. What's worse is, that the pending affinity mask is discarded even if it would contain a valid subset of the online CPUs. Implement a helper function which allows to avoid these issues. Signed-off-by: Thomas Gleixner Cc: Jens Axboe Cc: Marc Zyngier Cc: Michael Ellerman Cc: Keith Busch Cc: Peter Zijlstra Cc: Christoph Hellwig Link: http://lkml.kernel.org/r/20170619235444.691345468@linutronix.de --- include/linux/irq.h | 5 +++++ kernel/irq/migration.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 35 insertions(+) diff --git a/include/linux/irq.h b/include/linux/irq.h index 7e62e10e5856..d008065e2f4d 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -491,9 +491,14 @@ extern void irq_migrate_all_off_this_cpu(void); #if defined(CONFIG_SMP) && defined(CONFIG_GENERIC_PENDING_IRQ) void irq_move_irq(struct irq_data *data); void irq_move_masked_irq(struct irq_data *data); +bool irq_fixup_move_pending(struct irq_desc *desc, bool force_clear); #else static inline void irq_move_irq(struct irq_data *data) { } static inline void irq_move_masked_irq(struct irq_data *data) { } +static inline bool irq_fixup_move_pending(struct irq_desc *desc, bool fclear) +{ + return false; +} #endif extern int no_irq_affinity; diff --git a/kernel/irq/migration.c b/kernel/irq/migration.c index 37ddb7bda651..6ca054a3f91d 100644 --- a/kernel/irq/migration.c +++ b/kernel/irq/migration.c @@ -4,6 +4,36 @@ #include "internals.h" +/** + * irq_fixup_move_pending - Cleanup irq move pending from a dying CPU + * @desc: Interrupt descpriptor to clean up + * @force_clear: If set clear the move pending bit unconditionally. + * If not set, clear it only when the dying CPU is the + * last one in the pending mask. + * + * Returns true if the pending bit was set and the pending mask contains an + * online CPU other than the dying CPU. + */ +bool irq_fixup_move_pending(struct irq_desc *desc, bool force_clear) +{ + struct irq_data *data = irq_desc_get_irq_data(desc); + + if (!irqd_is_setaffinity_pending(data)) + return false; + + /* + * The outgoing CPU might be the last online target in a pending + * interrupt move. If that's the case clear the pending move bit. + */ + if (cpumask_any_and(desc->pending_mask, cpu_online_mask) >= nr_cpu_ids) { + irqd_clr_move_pending(data); + return false; + } + if (force_clear) + irqd_clr_move_pending(data); + return true; +} + void irq_move_masked_irq(struct irq_data *idata) { struct irq_desc *desc = irq_data_to_desc(idata); -- 2.30.2