linux/kernel/irq
Thomas Gleixner 81e2073c17 genirq: Disable interrupts for force threaded handlers
With interrupt force threading all device interrupt handlers are invoked
from kernel threads. Contrary to hard interrupt context the invocation only
disables bottom halfs, but not interrupts. This was an oversight back then
because any code like this will have an issue:

thread(irq_A)
  irq_handler(A)
    spin_lock(&foo->lock);

interrupt(irq_B)
  irq_handler(B)
    spin_lock(&foo->lock);

This has been triggered with networking (NAPI vs. hrtimers) and console
drivers where printk() happens from an interrupt which interrupted the
force threaded handler.

Now people noticed and started to change the spin_lock() in the handler to
spin_lock_irqsave() which affects performance or add IRQF_NOTHREAD to the
interrupt request which in turn breaks RT.

Fix the root cause and not the symptom and disable interrupts before
invoking the force threaded handler which preserves the regular semantics
and the usefulness of the interrupt force threading as a general debugging
tool.

For not RT this is not changing much, except that during the execution of
the threaded handler interrupts are delayed until the handler
returns. Vs. scheduling and softirq processing there is no difference.

For RT kernels there is no issue.

Fixes: 8d32a307e4 ("genirq: Provide forced interrupt threading")
Reported-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Johan Hovold <johan@kernel.org>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20210317143859.513307808@linutronix.de
2021-03-21 00:17:52 +01:00
..
affinity.c genirq/affinity: Remove const qualifier from node_to_cpumask argument 2019-08-28 12:20:43 +02:00
autoprobe.c genirq: Delay deactivation in free_irq() 2019-07-03 10:12:28 +02:00
chip.c irqchip updates for Linux 5.11 2020-12-15 10:48:07 +01:00
cpuhotplug.c genirq, sched/isolation: Isolate from handling managed interrupts 2020-01-22 16:29:49 +01:00
debug.h Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk 2018-02-01 13:36:15 -08:00
debugfs.c Merge branch 'irq/qcom-pdc-wakeup' into irq/irqchip-next 2020-10-06 11:28:03 +01:00
devres.c genirq/devres: Use struct_size() in devm_kzalloc() 2019-04-16 21:54:03 +02:00
dummychip.c genirq: Add missing SPDX identifiers 2018-03-20 14:23:28 +01:00
generic-chip.c genirq: Fix kernel-doc markups 2020-11-16 15:20:54 +01:00
handle.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
internals.h genirq/chip: Use the first chip in irq_chip_compose_msi_msg() 2020-09-16 16:52:28 +02:00
ipi.c genirq: Fix various typos in comments 2018-12-18 14:22:28 +01:00
irq_sim.c genirq/irq_sim: Fix typos in kernel doc (fnode -> fwnode) 2021-03-16 16:20:58 +01:00
irqdesc.c genirq: Fix export of irq_to_desc() for powerpc KVM 2020-12-25 11:02:39 -08:00
irqdomain.c irqdomain: Remove debugfs_file from struct irq_domain 2021-03-08 20:12:08 +00:00
Kconfig irqchip updates for Linux 5.11 2020-12-15 10:48:07 +01:00
Makefile genirq/timings: Add selftest for circular array 2019-06-12 10:47:04 +02:00
manage.c genirq: Disable interrupts for force threaded handlers 2021-03-21 00:17:52 +01:00
matrix.c genirq/matrix: Deal with the sillyness of for_each_cpu() on UP 2020-08-30 19:17:28 +02:00
migration.c genirq/migration: Avoid out of line call if pending is not set 2018-06-06 15:18:20 +02:00
msi.c genirq/msi: Activate Multi-MSI early when MSI_FLAG_ACTIVATE_EARLY is set 2021-01-30 01:22:31 +01:00
pm.c genirq/PM: Introduce IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND flag 2020-10-06 11:23:41 +01:00
proc.c genirq: Annotate irq stats data races 2020-12-15 16:19:30 +01:00
resend.c genirq: Use new tasklet API for resend_tasklet 2021-01-28 11:18:04 +01:00
settings.h genirq: Allow interrupts to be excluded from /proc/interrupts 2020-09-13 17:04:38 +01:00
spurious.c genirq: Add missing __must_hold() sparse annotation 2020-01-09 18:03:37 +01:00
timings.c kernel/: fix repeated words in comments 2020-10-16 11:11:19 -07:00