common/src/tx_thread_priority_change.c (threadx)

/**************************************************************************/ /* */ /* Copyright (c) Microsoft Corporation. All rights reserved. */ /* */ /* This software is licensed under the Microsoft Software License */ /* Terms for Microsoft Azure RTOS. Full text of the license can be */ /* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */ /* and in the root directory of this software. */ /* */ /**************************************************************************/ /**************************************************************************/ /**************************************************************************/ /** */ /** ThreadX Component */ /** */ /** Thread */ /** */ /**************************************************************************/ /**************************************************************************/ #define TX_SOURCE_CODE /* Include necessary system files. */ #include "tx_api.h" #include "tx_trace.h" #include "tx_thread.h" /**************************************************************************/ /* */ /* FUNCTION RELEASE */ /* */ /* _tx_thread_priority_change PORTABLE C */ /* 6.1 */ /* AUTHOR */ /* */ /* William E. Lamie, Microsoft Corporation */ /* */ /* DESCRIPTION */ /* */ /* This function changes the priority of the specified thread. It */ /* also returns the old priority and handles preemption if the calling */ /* thread is currently executing and the priority change results in a */ /* higher priority thread ready for execution. */ /* */ /* Note: the preemption threshold is automatically changed to the new */ /* priority. */ /* */ /* INPUT */ /* */ /* thread_ptr Pointer to thread to suspend */ /* new_priority New thread priority */ /* old_priority Old thread priority */ /* */ /* OUTPUT */ /* */ /* status Completion status */ /* */ /* CALLS */ /* */ /* _tx_thread_system_resume Resume thread */ /* _tx_thread_system_ni_resume Non-interruptable resume thread */ /* _tx_thread_system_suspend Suspend thread */ /* _tx_thread_system_ni_suspend Non-interruptable suspend thread */ /* _tx_thread_system_preempt_check Check for preemption */ /* */ /* CALLED BY */ /* */ /* Application Code */ /* */ /* RELEASE HISTORY */ /* */ /* DATE NAME DESCRIPTION */ /* */ /* 05-19-2020 William E. Lamie Initial Version 6.0 */ /* 09-30-2020 William E. Lamie Modified comment(s), and */ /* change thread state from */ /* TX_SUSPENDED to */ /* TX_PRIORITY_CHANGE before */ /* calling */ /* _tx_thread_system_suspend, */ /* resulting in version 6.1 */ /* */ /**************************************************************************/ UINT _tx_thread_priority_change(TX_THREAD *thread_ptr, UINT new_priority, UINT *old_priority) { TX_INTERRUPT_SAVE_AREA TX_THREAD *execute_ptr; TX_THREAD *next_execute_ptr; UINT original_priority; /* Lockout interrupts while the thread is being suspended. */ TX_DISABLE /* Save the previous priority. */ *old_priority = thread_ptr -> tx_thread_user_priority; /* If trace is enabled, insert this event into the trace buffer. */ TX_TRACE_IN_LINE_INSERT(TX_TRACE_THREAD_PRIORITY_CHANGE, thread_ptr, new_priority, thread_ptr -> tx_thread_priority, thread_ptr -> tx_thread_state, TX_TRACE_THREAD_EVENTS) /* Log this kernel call. */ TX_EL_THREAD_PRIORITY_CHANGE_INSERT /* Determine if this thread is currently ready. */ if (thread_ptr -> tx_thread_state != TX_READY) { /* Setup the user priority and threshold in the thread's control block. */ thread_ptr -> tx_thread_user_priority = new_priority; thread_ptr -> tx_thread_user_preempt_threshold = new_priority; /* Determine if the actual thread priority should be setup, which is the case if the new priority is higher than the priority inheritance. */ if (new_priority < thread_ptr -> tx_thread_inherit_priority) { /* Change thread priority to the new user's priority. */ thread_ptr -> tx_thread_priority = new_priority; thread_ptr -> tx_thread_preempt_threshold = new_priority; } else { /* Change thread priority to the priority inheritance. */ thread_ptr -> tx_thread_priority = thread_ptr -> tx_thread_inherit_priority; thread_ptr -> tx_thread_preempt_threshold = thread_ptr -> tx_thread_inherit_priority; } /* Restore interrupts. */ TX_RESTORE } else { /* Set the state to priority change. */ thread_ptr -> tx_thread_state = TX_PRIORITY_CHANGE; /* Pickup the next thread to execute. */ execute_ptr = _tx_thread_execute_ptr; /* Save the original priority. */ original_priority = thread_ptr -> tx_thread_priority; #ifdef TX_NOT_INTERRUPTABLE /* Increment the preempt disable flag. */ _tx_thread_preempt_disable++; /* Call actual non-interruptable thread suspension routine. */ _tx_thread_system_ni_suspend(thread_ptr, ((ULONG) 0)); /* At this point, the preempt disable flag is still set, so we still have protection against all preemption. */ /* Setup the new priority for this thread. */ thread_ptr -> tx_thread_user_priority = new_priority; thread_ptr -> tx_thread_user_preempt_threshold = new_priority; /* Determine if the actual thread priority should be setup, which is the case if the new priority is higher than the priority inheritance. */ if (new_priority < thread_ptr -> tx_thread_inherit_priority) { /* Change thread priority to the new user's priority. */ thread_ptr -> tx_thread_priority = new_priority; thread_ptr -> tx_thread_preempt_threshold = new_priority; } else { /* Change thread priority to the priority inheritance. */ thread_ptr -> tx_thread_priority = thread_ptr -> tx_thread_inherit_priority; thread_ptr -> tx_thread_preempt_threshold = thread_ptr -> tx_thread_inherit_priority; } /* Resume the thread with the new priority. */ _tx_thread_system_ni_resume(thread_ptr); #else /* Increment the preempt disable flag by 2 to prevent system suspend from returning to the system. */ _tx_thread_preempt_disable = _tx_thread_preempt_disable + ((UINT) 3); /* Set the suspending flag. */ thread_ptr -> tx_thread_suspending = TX_TRUE; /* Setup the timeout period. */ thread_ptr -> tx_thread_timer.tx_timer_internal_remaining_ticks = ((ULONG) 0); /* Restore interrupts. */ TX_RESTORE /* The thread is ready and must first be removed from the list. Call the system suspend function to accomplish this. */ _tx_thread_system_suspend(thread_ptr); /* At this point, the preempt disable flag is still set, so we still have protection against all preemption. */ /* Setup the new priority for this thread. */ thread_ptr -> tx_thread_user_priority = new_priority; thread_ptr -> tx_thread_user_preempt_threshold = new_priority; /* Determine if the actual thread priority should be setup, which is the case if the new priority is higher than the priority inheritance. */ if (new_priority < thread_ptr -> tx_thread_inherit_priority) { /* Change thread priority to the new user's priority. */ thread_ptr -> tx_thread_priority = new_priority; thread_ptr -> tx_thread_preempt_threshold = new_priority; } else { /* Change thread priority to the priority inheritance. */ thread_ptr -> tx_thread_priority = thread_ptr -> tx_thread_inherit_priority; thread_ptr -> tx_thread_preempt_threshold = thread_ptr -> tx_thread_inherit_priority; } /* Resume the thread with the new priority. */ _tx_thread_system_resume(thread_ptr); /* Disable interrupts. */ TX_DISABLE #endif /* Decrement the preempt disable flag. */ _tx_thread_preempt_disable--; /* Pickup the next thread to execute. */ next_execute_ptr = _tx_thread_execute_ptr; /* Determine if this thread is not the next thread to execute. */ if (thread_ptr != next_execute_ptr) { /* Make sure the thread is still ready. */ if (thread_ptr -> tx_thread_state == TX_READY) { /* Now check and see if this thread has an equal or higher priority. */ if (thread_ptr -> tx_thread_priority <= next_execute_ptr -> tx_thread_priority) { /* Now determine if this thread was the previously executing thread. */ if (thread_ptr == execute_ptr) { /* Yes, this thread was previously executing before we temporarily suspended and resumed it in order to change the priority. A lower or same priority thread cannot be the next thread to execute in this case since this thread really didn't suspend. Simply reset the execute pointer to this thread. */ _tx_thread_execute_ptr = thread_ptr; /* Determine if we moved to a lower priority. If so, move the thread to the front of its priority list. */ if (original_priority < new_priority) { /* Ensure that this thread is placed at the front of the priority list. */ _tx_thread_priority_list[thread_ptr -> tx_thread_priority] = thread_ptr; } } } } } /* Restore interrupts. */ TX_RESTORE /* Check for preemption. */ _tx_thread_system_preempt_check(); } /* Return success if we get here! */ return(TX_SUCCESS); }

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