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arch/intel64: fix self-deadlock in intel64_oneshot_start()

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intel64_oneshot_start() takes g_oneshot_spin and then, if the timer is
already running, calls intel64_oneshot_cancel(), which takes the same
spinlock again.  Spinlocks are not recursive, so the CPU spins forever
on its own lock while holding the critical section; the HPET timer ISR
on another CPU then blocks on g_cpu_irqlock and the system hangs.

This is hit as soon as the tickless scheduler re-arms a running HPET
oneshot timer under SMP (ostest task_restart, LTP aio tests).

Stop the running timer inline instead of calling cancel: disable the
interrupt, detach the ISR so up_enable_irq() does not assert on a busy
IRQ, and clear the running flag.  The ISR, comparator and interrupt
enable are reprogrammed by the rest of the function anyway.

Assisted-by: Claude Code
Signed-off-by: raiden00pl <raiden00@railab.me>
This commit is contained in:
raiden00pl 2026-09-02 15:24:45 +02:00 • committed by Xiang Xiao
parent 167dc72839
commit dfc8f82b0b
1 changed files with 13 additions and 2 deletions
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15
arch/x86_64/src/intel64/intel64_oneshot.c
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@ -301,10 +301,21 @@ int intel64_oneshot_start(struct intel64_oneshot_s *oneshot,
flags = spin_lock_irqsave(&g_oneshot_spin);
if (oneshot->running)
{
/* Yes.. then cancel it */
/* Yes.. then stop it. Do NOT call intel64_oneshot_cancel() here:
* it takes g_oneshot_spin, which we already hold, and spinlocks are
* not recursive, so that deadlocks the CPU. Everything else that
* cancel would do (ISR, comparator, interrupt enable) is
* reprogrammed below anyway.
*/
tmrinfo("Already running... cancelling\n");
intel64_oneshot_cancel(oneshot, NULL);
#ifndef CONFIG_INTEL64_HPET_FSB
INTEL64_TIM_DISABLEINT(oneshot->tch, oneshot->chan);
INTEL64_TIM_SETISR(oneshot->tch, oneshot->chan, NULL, NULL, false);
#endif
oneshot->running = false;
}
/* Save the new handler and its argument */