genirq: Move irq resource handling out of spinlocked region (46e48e25) · Commits · 戴 / test

Aside of being conceptually wrong, there is also an actual (hard to trigger and mostly theoretical) problem. CPU0 CPU1 free_irq(X) interrupt X spin_lock(desc->lock) wake irq thread() spin_unlock(desc->lock) spin_lock(desc->lock) remove action() shutdown_irq() release_resources() thread_handler() spin_unlock(desc->lock) access released resources. synchronize_irq() Move the release resources invocation after synchronize_irq() so it's guaranteed that the threaded handler has finished. Move the resource request call out of the desc->lock held region as well, so the invocation context is the same for both request and release. This solves the problems with those functions on RT as well. Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Reviewed-by:

Marc Zyngier <marc.zyngier@arm.com> Cc: Heiko Stuebner <heiko@sntech.de> Cc: Julia Cartwright <julia@ni.com> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Brian Norris <briannorris@chromium.org> Cc: Doug Anderson <dianders@chromium.org> Cc: linux-rockchip@lists.infradead.org Cc: John Keeping <john@metanate.com> Cc: linux-gpio@vger.kernel.org Link: http://lkml.kernel.org/r/20170629214344.117028181@linutronix.de

kernel/irq/manage.c

+15 −8

Original line number	Diff line number	Diff line
		@@ -1168,6 +1168,14 @@ __setup_irq(unsigned int irq, struct irq_desc desc, struct irqaction new)
		new->flags &= ~IRQF_ONESHOT;

		mutex_lock(&desc->request_mutex);
		if (!desc->action) {
		ret = irq_request_resources(desc);
		if (ret) {
		pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n",
		new->name, irq, desc->irq_data.chip->name);
		goto out_mutex;
		}
		}

		chip_bus_lock(desc);

		@@ -1271,13 +1279,6 @@ __setup_irq(unsigned int irq, struct irq_desc desc, struct irqaction new)
		}

		if (!shared) {
		ret = irq_request_resources(desc);
		if (ret) {
		pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n",
		new->name, irq, desc->irq_data.chip->name);
		goto out_unlock;
		}

		init_waitqueue_head(&desc->wait_for_threads);

		/* Setup the type (level, edge polarity) if configured: */
		@@ -1386,6 +1387,10 @@ out_unlock:

		chip_bus_sync_unlock(desc);

		if (!desc->action)
		irq_release_resources(desc);

		out_mutex:
		mutex_unlock(&desc->request_mutex);

		out_thread:
		@@ -1484,7 +1489,6 @@ static struct irqaction __free_irq(unsigned int irq, void dev_id)
		if (!desc->action) {
		irq_settings_clr_disable_unlazy(desc);
		irq_shutdown(desc);
		irq_release_resources(desc);
		irq_remove_timings(desc);
		}

		@@ -1527,6 +1531,9 @@ static struct irqaction __free_irq(unsigned int irq, void dev_id)
		}
		}

		if (!desc->action)
		irq_release_resources(desc);

		mutex_unlock(&desc->request_mutex);

		irq_chip_pm_put(&desc->irq_data);

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