sched/sem_waitirq: Move kmm_map() call to sem_wait() #366
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pussuw
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Mar 12, 2025
| @@ -100,6 +100,10 @@ void nxsem_recover(FAR struct tcb_s *tcb) | |||
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| sem->semcount++; | |||
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The kernel mapping should be performed in sem_wait (thread level) as virtual memory mappings cannot be added from interrupt, at least for now. The reason? kmm_map() depends on mm_map_add(), which in turn uses a mutex for mutual exclusion. Using mutexes from interrupt level is not permitted. Mapping tcb->waitobj into kernel virtual memory directly in sem_wait() makes sense, since accessing tcb->waitobj via a user virtual address can lead to unexpected results (the wrong mappings can be in place).
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pussuw
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Mar 13, 2025
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The kernel mapping should be performed in sem_wait (thread level) as virtual memory mappings cannot be added from interrupt, at least for now.
The reason?
kmm_map() depends on mm_map_add(), which in turn uses a mutex for mutual exclusion. Using mutexes from interrupt level is not permitted.
Mapping tcb->waitobj into kernel virtual memory directly in sem_wait() makes sense, since accessing tcb->waitobj via a user virtual address can lead to unexpected results (the wrong mappings can be in place).