xiaoxiang781216 commented on a change in pull request #4020:
URL: https://github.com/apache/incubator-nuttx/pull/4020#discussion_r662700570
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File path: sched/Kconfig
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@@ -268,13 +268,25 @@ config SMP
default n
depends on ARCH_HAVE_MULTICPU
depends on ARCH_HAVE_TESTSET
+ depends on ARCH_INTERRUPTSTACK != 0
select SPINLOCK
select SCHED_RESUMESCHEDULER
select IRQCOUNT
---help---
Enables support for Symmetric Multi-Processing (SMP) on a
multi-CPU
platform.
+ SMP mode must work with ARCH_INTERRUPTSTACK, here is the fail
case:
+
+ CPU0 thread0 -> IRQ enter -> add thread0 to block_list -> IRQ
leave(crash)
+ ||
+ /\
+ / \
+ CPU1 thread1 -> block_task -> take thread0 from block_list ->
run thread0
+
+ CPU0 IRQ handler use thread0's stack, but thread0 may switch to
CPU1, that
+ will caused IRQ handler stack curroption.
Review comment:
It's important to document this fact, but it's more important to express
the fact by contract and then avoid the wrong config in the future. It's a good
to add a select/depend ARCH_INTERRUPTSTACK here.
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