sched: Fix nx_waitid(), nx_waitpid(), nxtask_exithook() for SMP #2298
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Summary: - I noticed waitpid_test stops with lc823450-xgevk:rndis - The condition was CONFIG_DEBUG_ASSERTION=y - Actually, the child task sent SIGCHILD but the parent couldn't catch the signal - Then, I found that nx_waitid(), nx_waitpid() use sched_lock() - However, a parent task and a child task are running on different CPUs - So, sched_lock() is not enough and need to use a critical section - Also, signal handling in nxtask_exithook() must be done in a critical section Impact: - SMP only Testing: - Tested with ostest with the following configurations - lc823450-xgevk:rndis (CONFIG_DEBUG_ASSERTION=y and n) - spresense:smp - spresense:wifi_smp (NCPUS=2 and 4) - sabre-6quad:smp (QEMU) - esp32-core:smp (QEMU) - maix-bit:smp (QEMU) - sim:smp Signed-off-by: Masayuki Ishikawa <[email protected]>
Ouss4
reviewed
Nov 14, 2020
| */ | ||
|
|
||
| #ifdef CONFIG_SMP | ||
| irqstate_t flags = enter_critical_section(); |
There was a problem hiding this comment.
Isn't the call to sched_(un)lock in line 156 not needed then?
There was a problem hiding this comment.
@Ouss4
Thanks for your comment. I will modify the code and do the regression test again.
There was a problem hiding this comment.
@Ouss4
I tried the following change in sched_waitid.c and sched_waitpid.c
The ostest passed for the all SMP configurations.
However, Wi-Fi streaming plus stress testing with spresense:wifi_smp (NCPUS=4, DEBUG_ASSERTIONS=y)
failed with DEBUGASSERTION after 3.5 hours. (FYI, without the following changes, the test continued over 9 hours)
I think replacing sched_lock() and sched_unlock() with a critical section should be a future task.
What do you think?
#ifdef CONFIG_SMP
/* NOTE: sched_lock() is not enough for SMP
* because the child task is running on another CPU
*/
irqstate_t flags = enter_critical_section();
#else
/* Disable pre-emption so that nothing changes while the loop executes */
sched_lock();
#endif
...
#ifdef CONFIG_SMP
leave_critical_section(flags);
#else
sched_unlock();
#endif
|
See issue #1137 |
xiaoxiang781216
approved these changes
Nov 15, 2020
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Summary
Impact
Testing