Messages in this thread | | | From | Sebastian Andrzej Siewior <> | Subject | [PATCH v2 0/4] perf: Make SIGTRAP and __perf_pending_irq() work on RT. | Date | Tue, 12 Mar 2024 19:01:48 +0100 |
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Hi,
Arnaldo reported that "perf test sigtrap" fails on PREEMPT_RT. Sending the signal gets delayed until event_sched_out() which then uses task_work_add() for its delivery. This breaks on PREEMPT_RT because the signal is delivered with disabled preemption.
While looking at this, I also stumbled upon __perf_pending_irq() which requires disabled interrupts but this is not the case on PREEMPT_RT.
This series aim to address both issues while not introducing a new issue at the same time ;) Any testing is appreciated.
v1…v2: https://lore.kernel.org/all/20240308175810.2894694-1-bigeasy@linutronix.de/ - Marco pointed me to the testsuite that showed two problems: - Delayed task_work from NMI / missing events. Fixed by triggering dummy irq_work to enforce an interrupt for the exit-to-userland path which checks task_work - Increased ref-count on clean up/ during exec. Mostly addressed by the former change. There is still a window if the NMI occurs during execve(). This is addressed by removing the task_work before free_event(). The testsuite (remove_on_exec) fails sometimes if the event/ SIGTRAP is sent before the sighandler is installed.
Sebastian
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