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Posted to commits@nuttx.apache.org by GitBox <gi...@apache.org> on 2021/10/17 00:38:20 UTC
[GitHub] [incubator-nuttx] Ouss4 opened a new pull request #4669: arch/xtensa/xtensa_cpupause.c: Allow a spin before taking the g_cpu_wait spinlock.
Ouss4 opened a new pull request #4669:
URL: https://github.com/apache/incubator-nuttx/pull/4669
## Summary
If we repeatedly call `up_cpu_pause` and `up_cpu_resume`, there would be
cases where the next call to `up_cpu_pause` happens while the other CPU is
still responding to the previous resume request. In this case the
`DEBUGASSERT` will trigger. We should allow the first CPU to wait until the
other CPU has finished responding to the resume request.
## Impact
Xtensa multicore chips.
## Testing
`esp32-devkitc:wapi_smp` with other patches to come that makes it work again.
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[GitHub] [incubator-nuttx] xiaoxiang781216 merged pull request #4669: arch/xtensa/xtensa_cpupause.c: Allow a spin before taking the g_cpu_wait spinlock.
Posted by GitBox <gi...@apache.org>.
xiaoxiang781216 merged pull request #4669:
URL: https://github.com/apache/incubator-nuttx/pull/4669
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[GitHub] [incubator-nuttx] xiaoxiang781216 commented on a change in pull request #4669: arch/xtensa/xtensa_cpupause.c: Allow a spin before taking the g_cpu_wait spinlock.
Posted by GitBox <gi...@apache.org>.
xiaoxiang781216 commented on a change in pull request #4669:
URL: https://github.com/apache/incubator-nuttx/pull/4669#discussion_r730222823
##########
File path: arch/xtensa/src/common/xtensa_cpupause.c
##########
@@ -231,10 +231,12 @@ int up_cpu_pause(int cpu)
* handler from returning until up_cpu_resume() is called; g_cpu_paused
* is a handshake that will prevent this function from returning until
* the CPU is actually paused.
+ * Note that we might spin before getting g_cpu_wait, this just means that
+ * the other CPU still hasn't finished responding to the previous resume
+ * request.
*/
- DEBUGASSERT(!spin_islocked(&g_cpu_wait[cpu]) &&
Review comment:
The similar assert happen in other arch, should we relax other arch too?
##########
File path: arch/xtensa/src/common/xtensa_cpupause.c
##########
@@ -231,10 +231,12 @@ int up_cpu_pause(int cpu)
* handler from returning until up_cpu_resume() is called; g_cpu_paused
* is a handshake that will prevent this function from returning until
* the CPU is actually paused.
+ * Note that we might spin before getting g_cpu_wait, this just means that
+ * the other CPU still hasn't finished responding to the previous resume
+ * request.
*/
- DEBUGASSERT(!spin_islocked(&g_cpu_wait[cpu]) &&
Review comment:
Ok, let's merge this PR first. Please consider provide the patch to fix other arch too, thanks.
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[GitHub] [incubator-nuttx] Ouss4 commented on a change in pull request #4669: arch/xtensa/xtensa_cpupause.c: Allow a spin before taking the g_cpu_wait spinlock.
Posted by GitBox <gi...@apache.org>.
Ouss4 commented on a change in pull request #4669:
URL: https://github.com/apache/incubator-nuttx/pull/4669#discussion_r730242544
##########
File path: arch/xtensa/src/common/xtensa_cpupause.c
##########
@@ -231,10 +231,12 @@ int up_cpu_pause(int cpu)
* handler from returning until up_cpu_resume() is called; g_cpu_paused
* is a handshake that will prevent this function from returning until
* the CPU is actually paused.
+ * Note that we might spin before getting g_cpu_wait, this just means that
+ * the other CPU still hasn't finished responding to the previous resume
+ * request.
*/
- DEBUGASSERT(!spin_islocked(&g_cpu_wait[cpu]) &&
Review comment:
I think other archs will also hit the same issue if `up_cpu_pause` and `up_cpu_resume` are called repeatedly.
##########
File path: arch/xtensa/src/common/xtensa_cpupause.c
##########
@@ -231,10 +231,12 @@ int up_cpu_pause(int cpu)
* handler from returning until up_cpu_resume() is called; g_cpu_paused
* is a handshake that will prevent this function from returning until
* the CPU is actually paused.
+ * Note that we might spin before getting g_cpu_wait, this just means that
+ * the other CPU still hasn't finished responding to the previous resume
+ * request.
*/
- DEBUGASSERT(!spin_islocked(&g_cpu_wait[cpu]) &&
Review comment:
I think other archs will also hit the same issue if `up_cpu_pause` and `up_cpu_resume` are called repeatedly. So I also think we should relax that assertion in the other archs as well.
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