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kernel/swap: Move arch_cohere_stacks() back under the lock

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Commit 6b84ab3830 ("kernel/sched: Adjust locking in z_swap()") moved
the call to arch_cohere_stacks() out of the scheduler lock while doing
some reorgnizing.  On further reflection, this is incorrect.  When
done outside the lock, the two arch_cohere_stacks() calls will race
against each other.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This commit is contained in:
Andy Ross 2021-02-24 14:47:35 -08:00 • committed by Anas Nashif
commit deca2301f6
1 changed files with 2 additions and 1 deletions
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3
kernel/include/kswap.h
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@ -106,6 +106,8 @@ static ALWAYS_INLINE unsigned int do_swap(unsigned int key,
z_spin_lock_set_owner(&sched_spinlock);
#endif
arch_cohere_stacks(old_thread, NULL, new_thread);
#ifdef CONFIG_SMP
/* Add _current back to the run queue HERE. After
* wait_for_switch() we are guaranteed to reach the
@ -121,7 +123,6 @@ static ALWAYS_INLINE unsigned int do_swap(unsigned int key,
new_thread->switch_handle = NULL;
}
k_spin_release(&sched_spinlock);
arch_cohere_stacks(old_thread, NULL, new_thread);
arch_switch(newsh, &old_thread->switch_handle);
} else {
k_spin_release(&sched_spinlock);