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Posted to commits@nuttx.apache.org by GitBox <gi...@apache.org> on 2020/11/03 14:13:03 UTC

[GitHub] [incubator-nuttx] masayuki2009 opened a new pull request #2204: sched: irq: Fix enter_critical_section() in an irq handler for SMP

masayuki2009 opened a new pull request #2204:
URL: https://github.com/apache/incubator-nuttx/pull/2204


   ## 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
   


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[GitHub] [incubator-nuttx] jerpelea merged pull request #2204: sched: irq: Fix enter_critical_section() in an irq handler for SMP

Posted by GitBox <gi...@apache.org>.
jerpelea merged pull request #2204:
URL: https://github.com/apache/incubator-nuttx/pull/2204


   


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[GitHub] [incubator-nuttx] masayuki2009 commented on pull request #2204: sched: irq: Fix enter_critical_section() in an irq handler for SMP

Posted by GitBox <gi...@apache.org>.
masayuki2009 commented on pull request #2204:
URL: https://github.com/apache/incubator-nuttx/pull/2204#issuecomment-727957061


   @btashton 
   I noticed that the PR also needs to be backported to 10.0
   


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[GitHub] [incubator-nuttx] jerpelea commented on pull request #2204: sched: irq: Fix enter_critical_section() in an irq handler for SMP

Posted by GitBox <gi...@apache.org>.
jerpelea commented on pull request #2204:
URL: https://github.com/apache/incubator-nuttx/pull/2204#issuecomment-720944257


   LGTM


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[GitHub] [incubator-nuttx] btashton commented on pull request #2204: sched: irq: Fix enter_critical_section() in an irq handler for SMP

Posted by GitBox <gi...@apache.org>.
btashton commented on pull request #2204:
URL: https://github.com/apache/incubator-nuttx/pull/2204#issuecomment-728190331


   
   > I noticed that the PR also needs to be backported to 10.0
   > 
   
   Thanks for catching this. I added the label so I won't miss it this evening.


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