On Mon, Jun 10 2024 at 02:30, Peng Liu wrote:
> handle_nested_irq() is supposed to be running inside the parent thread
> handler context. It per se has no dedicated kernel thread, thus shouldn't
> touch desc->threads_active. The parent kernel thread has already taken
> care of this.
No it has not. The parent thread has marked itself in the parent threads
interrupt descriptor.
How does that help synchronizing the nested interrupt, which has a
separate interrupt descriptor?
> Fixes: e2c12739ccf7 ("genirq: Prevent nested thread vs synchronize_hardirq() deadlock")
> Cc: stable@xxxxxxxxxxxxxxx
There is nothing to fix.
> Signed-off-by: Peng Liu <iwtbavbm@xxxxxxxxx>
> ---
>
> Despite of its correctness, I'm afraid the testing on my only PC can't
> cover the affected code path. So the patch may be totally -UNTESTED-.
Which correctness?
The change log of the commit you want to "fix" says:
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.
It's very clearly spelled out, no?
Thanks,
tglx
