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task: Add new cancellation point interface, check_cancellation_point().

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This commit is contained in:
Gregory Nutt 2017-10-09 09:43:04 -06:00
parent e7c52bac60
commit 9b61cc6b25
2 changed files with 80 additions and 2 deletions
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27
include/nuttx/cancelpt.h
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@ -2,7 +2,7 @@
* include/nuttx/cancelpt.h
* Definitions related to cancellation points
*
* Copyright (C) 2016 Gregory Nutt. All rights reserved.
* Copyright (C) 2016-2017 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
@ -144,6 +144,31 @@ void leave_cancellation_point(void);
# define leave_cancellation_point()
#endif
/****************************************************************************
* Name: check_cancellation_point
*
* Description:
* Returns true if:
*
* 1. Deferred cancellation does applies to this thread,
* 2. We are within a cancellation point (i.e., the nesting level in the
* TCB is greater than zero).
*
* Input Parameters:
* None
*
* Returned Value
* true is returned if a cancellation is pending but cannot be performed
* now due to the nesting level.
*
****************************************************************************/
#ifdef CONFIG_CANCELLATION_POINTS
bool check_cancellation_point(void);
#else
# define check_cancellation_point() false
#endif
#undef EXTERN
#ifdef __cplusplus
}

55
sched/task/task_cancelpt.c
View File

@ -1,7 +1,7 @@
/****************************************************************************
* sched/task/task_cancelpt.c
*
* Copyright (C) 2016 Gregory Nutt. All rights reserved.
* Copyright (C) 2016-2017 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
@ -260,6 +260,59 @@ void leave_cancellation_point(void)
sched_unlock();
}
/****************************************************************************
* Name: check_cancellation_point
*
* Description:
* Returns true if:
*
* 1. Deferred cancellation does applies to this thread,
* 2. We are within a cancellation point (i.e., the nesting level in the
* TCB is greater than zero).
*
* Input Parameters:
* None
*
* Returned Value
* true is returned if a cancellation is pending but cannot be performed
* now due to the nesting level.
*
****************************************************************************/
bool check_cancellation_point(void)
{
FAR struct tcb_s *tcb = this_task();
bool ret = false;
/* Disabling pre-emption should provide sufficient protection. We only
* need the TCB to be stationary (no interrupt level modification is
* anticipated).
*
* REVISIT: is locking the scheduler sufficent in SMP mode?
*/
sched_lock();
/* If cancellation is disabled on this thread or if this thread is using
* asynchronous cancellation, then return false.
*
* If the cpcount count is greater than zero, then we within a
* cancellation and will true if there is a pending cancellation.
*/
if (((tcb->flags & TCB_FLAG_NONCANCELABLE) == 0 &&
(tcb->flags & TCB_FLAG_CANCEL_DEFERRED) != 0) ||
tcb->cpcount > 0)
{
/* Check if there is a pending cancellation. If so, return true. */
ret = ((tcb->flags & TCB_FLAG_CANCEL_PENDING) != 0);
}
sched_unlock();
return ret;
}
/****************************************************************************
* Name: notify_cancellation
*