nuttx/sched/semaphore/sem_post.c

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/****************************************************************************
* sched/semaphore/sem_post.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <limits.h>
#include <errno.h>
#include <sched.h>
#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include "sched/sched.h"
#include "semaphore/semaphore.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nxsem_post
*
* Description:
* When a kernel thread has finished with a semaphore, it will call
* nxsem_post(). This function unlocks the semaphore referenced by sem
* by performing the semaphore unlock operation on that semaphore.
*
* If the semaphore value resulting from this operation is positive, then
* no tasks were blocked waiting for the semaphore to become unlocked; the
* semaphore is simply incremented.
*
* If the value of the semaphore resulting from this operation is zero,
* then one of the tasks blocked waiting for the semaphore shall be
* allowed to return successfully from its call to nxsem_wait().
*
* Input Parameters:
* sem - Semaphore descriptor
*
* Returned Value:
* This is an internal OS interface and should not be used by applications.
* It follows the NuttX internal error return policy: Zero (OK) is
* returned on success. A negated errno value is returned on failure.
*
* Assumptions:
2014-11-07 22:54:24 +01:00
* This function may be called from an interrupt handler.
*
****************************************************************************/
int nxsem_post(FAR sem_t *sem)
{
FAR struct tcb_s *stcb = NULL;
irqstate_t flags;
int16_t sem_count;
DEBUGASSERT(sem != NULL);
/* The following operations must be performed with interrupts
* disabled because sem_post() may be called from an interrupt
* handler.
*/
flags = enter_critical_section();
sem_count = sem->semcount;
/* Check the maximum allowable value */
DEBUGASSERT(sem_count < SEM_VALUE_MAX);
/* Perform the semaphore unlock operation, releasing this task as a
* holder then also incrementing the count on the semaphore.
*
* NOTE: When semaphores are used for signaling purposes, the holder
* of the semaphore may not be this thread! In this case,
* nxsem_release_holder() will do nothing.
*
* In the case of a mutex this could be simply resolved since there is
* only one holder but for the case of counting semaphores, there may
* be many holders and if the holder is not this thread, then it is
* not possible to know which thread/holder should be released.
*
* For this reason, it is recommended that priority inheritance be
* disabled via nxsem_set_protocol(SEM_PRIO_NONE) when the semaphore is
* initialized if the semaphore is to used for signaling purposes.
*/
nxsem_release_holder(sem);
sem_count++;
sem->semcount = sem_count;
#ifdef CONFIG_PRIORITY_INHERITANCE
/* Don't let any unblocked tasks run until we complete any priority
* restoration steps. Interrupts are disabled, but we do not want
* the head of the ready-to-run list to be modified yet.
*
* NOTE: If this sched_lock is called from an interrupt handler, it
* will do nothing.
*/
sched_lock();
#endif
/* If the result of semaphore unlock is non-positive, then
* there must be some task waiting for the semaphore.
*/
if (sem_count <= 0)
{
/* Check if there are any tasks in the waiting for semaphore
* task list that are waiting for this semaphore. This is a
* prioritized list so the first one we encounter is the one
* that we want.
*/
stcb = (FAR struct tcb_s *)dq_remfirst(SEM_WAITLIST(sem));
if (stcb != NULL)
{
FAR struct tcb_s *rtcb = this_task();
/* The task will be the new holder of the semaphore when
* it is awakened.
*/
nxsem_add_holder_tcb(stcb, sem);
/* Stop the watchdog timer */
semaphore: fix corner case sem_waitirq assert crash [ 11.041077] [25] [ EMERG] [ap] up_assert: Assertion failed at file:semaphore/sem_waitirq.c line: 84 task: thermal service [ 11.041407] [25] [ EMERG] [ap] backtrace: [ 11.041517] [25] [ EMERG] [ap] [25] [<0x2c687c9e>] up_backtrace+0xa/0x164 [ 11.041627] [25] [ EMERG] [ap] [25] [<0x2c676e6c>] sched_dumpstack+0x1c/0x5c [ 11.041682] [25] [ EMERG] [ap] [25] [<0x2c68763a>] up_assert+0x42/0x24c [ 11.041792] [25] [ EMERG] [ap] [25] [<0x2c67355e>] _assert+0x2/0xc [ 11.041847] [25] [ EMERG] [ap] [25] [<0x2c65d536>] nxsem_wait_irq+0x3e/0x134 [ 11.042288] [25] [ EMERG] [ap] [25] [<0x2c65d378>] nxsem_timeout+0x24/0x34 [ 11.043169] [25] [ EMERG] [ap] [25] [<0x2c65f74c>] wd_timer+0xc0/0x104 [ 11.043995] [25] [ EMERG] [ap] [25] [<0x2c65c930>] nxsched_alarm_expiration+0x4c/0xdc [ 11.044986] [25] [ EMERG] [ap] [25] [<0x2c670872>] oneshot_callback+0x16/0x24 [ 11.045867] [25] [ EMERG] [ap] [25] [<0x2c6822b8>] bes_oneshot_irq_handler+0x18/0x28 [ 11.046858] [25] [ EMERG] [ap] [25] [<0x57e5c>] up_irq_handler+0x4/0xc [ 11.047684] [25] [ EMERG] [ap] [25] [<0x2c65a20e>] irq_dispatch+0x5a/0xb8 [ 11.048510] [25] [ EMERG] [ap] [25] [<0x2c6864d8>] arm_doirq+0x28/0x3c [ 11.049336] [25] [ EMERG] [ap] [25] [<0x2c681732>] exception_common+0x4a/0xac [ 11.050272] [25] [ EMERG] [ap] [25] [<0x2c65a324>] leave_critical_section+0x2c/0x54 [ 11.051208] [25] [ EMERG] [ap] [25] [<0x2c65f472>] timer_settime+0x9e/0x10c There are 2 ways can caused this: 1. sem_timedwait HW IRQ sem_post TIMER IRQ do wd_timer -> nxsem_timeout -> crash Note: The 2 IRQS happens amost at same time 2. sem_timedwait TIMER IRQ do wd_timer -> wd_func1 sem_post -> wd_func2 nxsem_timeout -> crash Resolve: Stop the watchdog when sem_post Signed-off-by: ligd <liguiding1@xiaomi.com>
2022-02-16 06:37:38 +01:00
if (WDOG_ISACTIVE(&stcb->waitdog))
{
wd_cancel(&stcb->waitdog);
}
semaphore: fix corner case sem_waitirq assert crash [ 11.041077] [25] [ EMERG] [ap] up_assert: Assertion failed at file:semaphore/sem_waitirq.c line: 84 task: thermal service [ 11.041407] [25] [ EMERG] [ap] backtrace: [ 11.041517] [25] [ EMERG] [ap] [25] [<0x2c687c9e>] up_backtrace+0xa/0x164 [ 11.041627] [25] [ EMERG] [ap] [25] [<0x2c676e6c>] sched_dumpstack+0x1c/0x5c [ 11.041682] [25] [ EMERG] [ap] [25] [<0x2c68763a>] up_assert+0x42/0x24c [ 11.041792] [25] [ EMERG] [ap] [25] [<0x2c67355e>] _assert+0x2/0xc [ 11.041847] [25] [ EMERG] [ap] [25] [<0x2c65d536>] nxsem_wait_irq+0x3e/0x134 [ 11.042288] [25] [ EMERG] [ap] [25] [<0x2c65d378>] nxsem_timeout+0x24/0x34 [ 11.043169] [25] [ EMERG] [ap] [25] [<0x2c65f74c>] wd_timer+0xc0/0x104 [ 11.043995] [25] [ EMERG] [ap] [25] [<0x2c65c930>] nxsched_alarm_expiration+0x4c/0xdc [ 11.044986] [25] [ EMERG] [ap] [25] [<0x2c670872>] oneshot_callback+0x16/0x24 [ 11.045867] [25] [ EMERG] [ap] [25] [<0x2c6822b8>] bes_oneshot_irq_handler+0x18/0x28 [ 11.046858] [25] [ EMERG] [ap] [25] [<0x57e5c>] up_irq_handler+0x4/0xc [ 11.047684] [25] [ EMERG] [ap] [25] [<0x2c65a20e>] irq_dispatch+0x5a/0xb8 [ 11.048510] [25] [ EMERG] [ap] [25] [<0x2c6864d8>] arm_doirq+0x28/0x3c [ 11.049336] [25] [ EMERG] [ap] [25] [<0x2c681732>] exception_common+0x4a/0xac [ 11.050272] [25] [ EMERG] [ap] [25] [<0x2c65a324>] leave_critical_section+0x2c/0x54 [ 11.051208] [25] [ EMERG] [ap] [25] [<0x2c65f472>] timer_settime+0x9e/0x10c There are 2 ways can caused this: 1. sem_timedwait HW IRQ sem_post TIMER IRQ do wd_timer -> nxsem_timeout -> crash Note: The 2 IRQS happens amost at same time 2. sem_timedwait TIMER IRQ do wd_timer -> wd_func1 sem_post -> wd_func2 nxsem_timeout -> crash Resolve: Stop the watchdog when sem_post Signed-off-by: ligd <liguiding1@xiaomi.com>
2022-02-16 06:37:38 +01:00
/* Indicate that the wait is over. */
stcb->waitobj = NULL;
/* Add the task to ready-to-run task list and
* perform the context switch if one is needed
*/
if (nxsched_add_readytorun(stcb))
{
up_switch_context(stcb, rtcb);
}
}
#if 0 /* REVISIT: This can fire on IOB throttle semaphore */
else
{
/* This should not happen. */
DEBUGPANIC();
}
#endif
}
/* Check if we need to drop the priority of any threads holding
* this semaphore. The priority could have been boosted while they
* held the semaphore.
*/
#ifdef CONFIG_PRIORITY_INHERITANCE
nxsem_restore_baseprio(stcb, sem);
sched_unlock();
#endif
/* Interrupts may now be enabled. */
leave_critical_section(flags);
return OK;
}
/****************************************************************************
* Name: sem_post
*
* Description:
* When a task has finished with a semaphore, it will call sem_post().
* This function unlocks the semaphore referenced by sem by performing the
* semaphore unlock operation on that semaphore.
*
* If the semaphore value resulting from this operation is positive, then
* no tasks were blocked waiting for the semaphore to become unlocked; the
* semaphore is simply incremented.
*
* If the value of the semaphore resulting from this operation is zero,
* then one of the tasks blocked waiting for the semaphore shall be
* allowed to return successfully from its call to nxsem_wait().
*
* Input Parameters:
* sem - Semaphore descriptor
*
* Returned Value:
* This function is a standard, POSIX application interface. It will
* return zero (OK) if successful. Otherwise, -1 (ERROR) is returned and
* the errno value is set appropriately.
*
* Assumptions:
* This function may be called from an interrupt handler.
*
****************************************************************************/
int sem_post(FAR sem_t *sem)
{
int ret;
/* Make sure we were supplied with a valid semaphore. */
if (sem == NULL)
{
set_errno(EINVAL);
return ERROR;
}
ret = nxsem_post(sem);
if (ret < 0)
{
set_errno(-ret);
ret = ERROR;
}
return ret;
}