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H A Dinternals.hdiff e2c12739ccf76aae12e9e949526a475b9d17adaa Thu Jul 06 09:22:25 CDT 2023 Vincent Whitchurch <vincent.whitchurch@axis.com> genirq: Prevent nested thread vs synchronize_hardirq() deadlock

There is a possibility of deadlock if synchronize_hardirq() is called
when the nested threaded interrupt is active. The following scenario
was observed on a uniprocessor PREEMPT_NONE system:

Thread 1 Thread 2

handle_nested_thread()
Set INPROGRESS
Call ->thread_fn()
thread_fn goes to sleep

free_irq()
__synchronize_hardirq()
Busy-loop forever waiting for INPROGRESS
to be cleared

The INPROGRESS flag is only supposed to be used for hard interrupt
handlers. Remove the incorrect usage in the nested threaded interrupt
case and instead re-use the threads_active / wait_for_threads mechanism
to wait for nested threaded interrupts to complete.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230613-genirq-nested-v3-1-ae58221143eb@axis.com
H A Dchip.cdiff e2c12739ccf76aae12e9e949526a475b9d17adaa Thu Jul 06 09:22:25 CDT 2023 Vincent Whitchurch <vincent.whitchurch@axis.com> genirq: Prevent nested thread vs synchronize_hardirq() deadlock

There is a possibility of deadlock if synchronize_hardirq() is called
when the nested threaded interrupt is active. The following scenario
was observed on a uniprocessor PREEMPT_NONE system:

Thread 1 Thread 2

handle_nested_thread()
Set INPROGRESS
Call ->thread_fn()
thread_fn goes to sleep

free_irq()
__synchronize_hardirq()
Busy-loop forever waiting for INPROGRESS
to be cleared

The INPROGRESS flag is only supposed to be used for hard interrupt
handlers. Remove the incorrect usage in the nested threaded interrupt
case and instead re-use the threads_active / wait_for_threads mechanism
to wait for nested threaded interrupts to complete.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230613-genirq-nested-v3-1-ae58221143eb@axis.com
H A Dmanage.cdiff e2c12739ccf76aae12e9e949526a475b9d17adaa Thu Jul 06 09:22:25 CDT 2023 Vincent Whitchurch <vincent.whitchurch@axis.com> genirq: Prevent nested thread vs synchronize_hardirq() deadlock

There is a possibility of deadlock if synchronize_hardirq() is called
when the nested threaded interrupt is active. The following scenario
was observed on a uniprocessor PREEMPT_NONE system:

Thread 1 Thread 2

handle_nested_thread()
Set INPROGRESS
Call ->thread_fn()
thread_fn goes to sleep

free_irq()
__synchronize_hardirq()
Busy-loop forever waiting for INPROGRESS
to be cleared

The INPROGRESS flag is only supposed to be used for hard interrupt
handlers. Remove the incorrect usage in the nested threaded interrupt
case and instead re-use the threads_active / wait_for_threads mechanism
to wait for nested threaded interrupts to complete.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230613-genirq-nested-v3-1-ae58221143eb@axis.com