Gregory Nutt 3e13ed2400 Within the OS, when a thread obtains a semaphore count it must call sem_addholder() if CONFIG_PRIORITY_INHERITANCE is enabled. If a count is available, then sem_wait() calls sem_addholder(), otherwise it waited for the semaphore and called sem_addholder() when it eventually received the count. ...

This caused a problem when the thread calling sem_wait() was very low priority.  When it received the count, there may be higher priority threads "hogging" the CPU that prevent the lower priority task from running and, as a result, the sem_addholder() may be delayed indefinitely.

The fix was to have sem_post() call sem_addholder() just before restarting the thread waiting for the semaphore count.

This problem was noted by Benix Vincent who also suggested the solution.

2016-10-26 07:23:15 -06:00

..

Make.defs

sched/semaphore: Add an internal interface to reset a semaphore count.

2016-03-05 07:33:24 -06:00

sem_destroy.c

Remove some empty file section section header comments

2016-02-17 17:38:39 -06:00

sem_holder.c

Within the OS, when a thread obtains a semaphore count it must call sem_addholder() if CONFIG_PRIORITY_INHERITANCE is enabled. If a count is available, then sem_wait() calls sem_addholder(), otherwise it waited for the semaphore and called sem_addholder() when it eventually received the count.

2016-10-26 07:23:15 -06:00

sem_initialize.c

sem_tickwait(): Add a new, non-standard function to perform timed semaphore waits. It is functionally equialent to the standard sem_timedwait(), but more efficient for use in higher performance device drivers. Requested by Max Neklyudov

2015-08-01 07:31:09 -06:00

sem_post.c

Within the OS, when a thread obtains a semaphore count it must call sem_addholder() if CONFIG_PRIORITY_INHERITANCE is enabled. If a count is available, then sem_wait() calls sem_addholder(), otherwise it waited for the semaphore and called sem_addholder() when it eventually received the count.

2016-10-26 07:23:15 -06:00

sem_recover.c

nuttx/sched: Replace irqsave() with enter_critical_section(); replace irqrestore() with leave_critical_section()

2016-02-14 08:17:46 -06:00

sem_reset.c

Update some comments

2016-03-06 13:50:26 -06:00

sem_tickwait.c

nuttx/sched: Replace irqsave() with enter_critical_section(); replace irqrestore() with leave_critical_section()

2016-02-14 08:17:46 -06:00

sem_timedwait.c

Rename CONFIG_DEBUG to CONFIG_DEBUG_FEATURES

2016-06-11 14:14:08 -06:00

sem_timeout.c

nuttx/sched: Replace irqsave() with enter_critical_section(); replace irqrestore() with leave_critical_section()

2016-02-14 08:17:46 -06:00

sem_trywait.c

nuttx/sched: Replace irqsave() with enter_critical_section(); replace irqrestore() with leave_critical_section()

2016-02-14 08:17:46 -06:00

sem_wait.c

Within the OS, when a thread obtains a semaphore count it must call sem_addholder() if CONFIG_PRIORITY_INHERITANCE is enabled. If a count is available, then sem_wait() calls sem_addholder(), otherwise it waited for the semaphore and called sem_addholder() when it eventually received the count.

2016-10-26 07:23:15 -06:00

sem_waitirq.c

nuttx/sched: Replace irqsave() with enter_critical_section(); replace irqrestore() with leave_critical_section()

2016-02-14 08:17:46 -06:00

semaphore.h

Within the OS, when a thread obtains a semaphore count it must call sem_addholder() if CONFIG_PRIORITY_INHERITANCE is enabled. If a count is available, then sem_wait() calls sem_addholder(), otherwise it waited for the semaphore and called sem_addholder() when it eventually received the count.

2016-10-26 07:23:15 -06:00

spinlock.c

Rename cpuset_t to cpu_set_t which is the type used in some non-standard Linux/GNU interfaces. Move definitions of cpu_set_t to include/sys/types.h. Add prototypes for sched_setaffinity(), sched_getaffinity(), pthread_attr_setaffinity_np(), pthread_attr_getaffinity_np(), pthread_setaffinity_np(), and pthread_getaffinity_np(). No implementation is yet in place.

2016-02-19 15:57:07 -06:00