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91008cf1b1
clock_get_sched_ticks() stored the value of read_seqbegin(), a uint32_t, in an unsigned int and passed it back to read_seqretry(). Where int is 16 bits the copy is truncated, so once the 32-bit sequence number passes 65535 read_seqretry() always reports a change and the loop never ends. The sequence advances once per tick, so after 65536 ticks (11 minutes at 100 Hz) the next caller, the timer interrupt itself, spins forever with interrupts disabled and the system stops. Seen on the CDP1802 (16-bit int): NSH stopped answering after 55 minutes at 20 Hz. AVR has the same problem. hrtimer's readers of the same lock already use uint32_t. Don't assume int is 32-bit :-D Signed-off-by: Alan Carvalho de Assis <acassis@gmail.com> Assisted-by: Claude Opus 5.5 (claude-opus-5-5)
130 lines
4.1 KiB
C
130 lines
4.1 KiB
C
/****************************************************************************
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* sched/clock/clock_sched_ticks.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include <nuttx/clock.h>
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#include <nuttx/seqlock.h>
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#include "clock/clock.h"
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static volatile clock_t g_system_ticks = INITIAL_SYSTEM_TIMER_TICKS;
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static seqcount_t g_system_tick_lock = SEQLOCK_INITIALIZER;
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: clock_update_sched_ticks
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*
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* Description:
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* Update the scheduler tick counter to a specific value. This function
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* directly sets the system tick counter to the given value (rather than
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* incrementing it), typically used for synchronizing or resetting the
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* scheduler tick count to a known state.
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*
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* Input Parameters:
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* ticks - The new value to set for the scheduler tick counter
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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void clock_update_sched_ticks(clock_t ticks)
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{
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irqstate_t flags;
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/* Increment the per-tick scheduler counter */
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flags = write_seqlock_irqsave(&g_system_tick_lock);
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g_system_ticks = ticks;
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write_sequnlock_irqrestore(&g_system_tick_lock, flags);
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}
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/****************************************************************************
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* Name: clock_increase_sched_ticks
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*
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* Description:
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* Increment the scheduler tick counter. This function should be called
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* each time the real-time clock interrupt occurs, indicating the passage
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* of one or more scheduling ticks.
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*
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* Input Parameters:
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* ticks - The number of ticks to increment (typically 1)
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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void clock_increase_sched_ticks(clock_t ticks)
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{
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irqstate_t flags;
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/* Increment the per-tick scheduler counter */
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flags = write_seqlock_irqsave(&g_system_tick_lock);
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g_system_ticks += ticks;
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write_sequnlock_irqrestore(&g_system_tick_lock, flags);
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}
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/****************************************************************************
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* Name: clock_get_sched_ticks
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*
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* Description:
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* Return the current value of the scheduler tick counter. This counter
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* only increases while the scheduler is running, and is independent of
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* the real-time clock.
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*
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* Returned Value:
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* The current number of scheduler ticks.
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*
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****************************************************************************/
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clock_t clock_get_sched_ticks(void)
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{
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clock_t ret;
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uint32_t seq;
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do
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{
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seq = read_seqbegin(&g_system_tick_lock);
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ret = g_system_ticks;
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}
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while (read_seqretry(&g_system_tick_lock, seq));
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return ret;
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}
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