diff --git a/TODO b/TODO index 8998fb1a46..93db26ced4 100644 --- a/TODO +++ b/TODO @@ -1,4 +1,4 @@ -NuttX TODO List (Last updated April 10, 2017) +NuttX TODO List (Last updated April 12, 2017) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This file summarizes known NuttX bugs, limitations, inconsistencies with @@ -9,7 +9,7 @@ issues related to each board port. nuttx/: - (10) Task/Scheduler (sched/) + (11) Task/Scheduler (sched/) (1) SMP (1) Memory Management (mm/) (0) Power Management (drivers/pm) @@ -186,6 +186,47 @@ o Task/Scheduler (sched/) Priority: Low. Things are just the way that we want them for the way that NuttX is used today. + Title: INTERNAL VERSIONS OF USER FUNCTIONS + Description: The internal NuttX logic uses the same interfaces as does + the application. That sometime produces a problem because + there is "overloaded" functionality in those user interfaces + that are not desireable. + + For example, having cancellation points hidden inside of the + OS can cause non-cancellation point interfaces to behave + strangely. There was a change recently in pthread_cond_wait() + and pthread_cond_timedwait() recently to effectively disable + the cancellation point behavior of sem_init(). This was + accomplished with two functions: pthread_disable_cancel() + and pthread_enable_cancel() + + Here is another issue:  Internal OS functions should not set + errno and should never have to look at the errno value to + determine the cause of the failure.  The errno is provided + for compatibility with POSIX application interface + requirements and really doesn't need to be used within the + OS. + + Both of these could be fixed if there were special internal + versions these functions.  For example, there could be a an + nx_sem_wait() that does all of the same things as sem_wait() + was does not create a cancellation point and does not set + the errno value on failures. + + Everything inside the OS would use nx_sem_wait(). + Applications would call sem_wait() which would just be a + wrapper around nx_sem_wait() that adds the cancellation point + and that sets the errno value on failures. + + Changes like that could clean up some of this internal + craziness.  The condition variable change described above is + really a "bandaid" to handle the case that sem_wait() is a + cancellation point. + Status: Open + Priority: Low. Things are working OK the way they are. But the design + could be improved and made a little more efficient with this + change. + o SMP ^^^