sched: irq: Fix enter_critical_section() in an irq handler for SMP #2204
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Summary: - I found a deadlock during Wi-Fi audio streaming test plus stress test - The testing environment was spresense:wifi_smp (NCPUS=4) - The deadlock happened because two CPUs called up_cpu_pause() almost simultaneously - This situation should not happen, because up_cpu_pause() is called in a critical section - Actually, the latter call was from nxsem_post() in an IRQ handler - And when enter_critical_section() was called, irq_waitlock() detected a deadlock - Then it called up_cpu_paused() to break the deadlock - However, this resulted in setting g_cpu_irqset on the CPU - Even though another CPU had held a g_cpu_irqlock - This situation violates the critical section and should be avoided - To avoid the situation, if a CPU sets g_cpu_irqset after calling up_cpu_paused() - The CPU must release g_cpu_irqlock first - Then retry irq_waitlock() to acquire g_cpu_irqlock Impact: - Affect SMP Testing: - Tested with spresense:wifi_smp (NCPUS=2 and 4) - Tested with spresense:smp - Tested with sim:smp - Tested with sabre-6quad:smp (QEMU) - Tested with maix-bit:smp (QEMU) - Tested with esp32-core:smp (QEMU) - Tested with lc823450-xgevk:rndis Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>
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LGTM |
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Author
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@btashton |
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Thanks for catching this. I added the label so I won't miss it this evening. |
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Summary
Impact
Testing