timerfd: remove timeout work and do notify in isr
1.Optimize notification speed 2.using enter/leave critical to replace spin_lock to avoid race condition Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>
This commit is contained in:
dongjiuzhu1
Xiang Xiao
parent
c7eca3d176
commit
d36b7fea45
1 changed files with 50 additions and 128 deletions
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@ -32,8 +32,6 @@
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#include <debug.h>
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#include <nuttx/wdog.h>
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#include <nuttx/wqueue.h>
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#include <nuttx/spinlock.h>
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#include <nuttx/mutex.h>
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#include <sys/ioctl.h>
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@ -46,8 +44,6 @@
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* Pre-processor Definitions
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****************************************************************************/
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#define TIMER_FD_WORK LPWORK
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/****************************************************************************
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* Private Types
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****************************************************************************/
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@ -68,9 +64,7 @@ struct timerfd_priv_s
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int delay; /* If non-zero, used to reset repetitive
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* timers */
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struct wdog_s wdog; /* The watchdog that provides the timing */
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struct work_s work; /* For deferred timeout operations */
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timerfd_t counter; /* timerfd counter */
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spinlock_t splock; /* timerfd counter specific lock */
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uint8_t crefs; /* References counts on timerfd (max: 255) */
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/* The following is a list if poll structures of threads waiting for
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@ -103,8 +97,7 @@ static int timerfd_blocking_io(FAR struct timerfd_priv_s *dev,
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static FAR struct timerfd_priv_s *timerfd_allocdev(void);
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static void timerfd_destroy(FAR struct timerfd_priv_s *dev);
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static void timerfd_timeout_work(FAR void *arg);
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static void timerfd_timeout(wdparm_t idev);
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static void timerfd_timeout(wdparm_t arg);
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/****************************************************************************
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* Private Data
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@ -164,24 +157,11 @@ static FAR struct timerfd_priv_s *timerfd_allocdev(void)
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static void timerfd_destroy(FAR struct timerfd_priv_s *dev)
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{
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wd_cancel(&dev->wdog);
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work_cancel(TIMER_FD_WORK, &dev->work);
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nxmutex_unlock(&dev->lock);
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nxmutex_destroy(&dev->lock);
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kmm_free(dev);
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}
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static timerfd_t timerfd_get_counter(FAR struct timerfd_priv_s *dev)
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{
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timerfd_t counter;
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irqstate_t intflags;
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intflags = spin_lock_irqsave(&dev->splock);
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counter = dev->counter;
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spin_unlock_irqrestore(&dev->splock, intflags);
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return counter;
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}
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static int timerfd_open(FAR struct file *filep)
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{
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FAR struct timerfd_priv_s *priv = filep->f_priv;
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@ -256,22 +236,13 @@ static int timerfd_blocking_io(FAR struct timerfd_priv_s *dev,
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sem->next = *slist;
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*slist = sem;
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nxmutex_unlock(&dev->lock);
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/* Wait for timerfd to notify */
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ret = nxsem_wait(&sem->sem);
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if (ret < 0)
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{
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FAR timerfd_waiter_sem_t *cur_sem;
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/* Interrupted wait, unregister semaphore
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* TODO ensure that lock wait does not fail (ECANCELED)
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*/
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nxmutex_lock(&dev->lock);
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cur_sem = *slist;
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if (cur_sem == sem)
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{
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@ -288,12 +259,9 @@ static int timerfd_blocking_io(FAR struct timerfd_priv_s *dev,
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}
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}
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}
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nxmutex_unlock(&dev->lock);
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return ret;
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}
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return nxmutex_lock(&dev->lock);
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return ret;
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}
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static ssize_t timerfd_read(FAR struct file *filep, FAR char *buffer,
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@ -308,21 +276,22 @@ static ssize_t timerfd_read(FAR struct file *filep, FAR char *buffer,
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return -EINVAL;
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}
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ret = nxmutex_lock(&dev->lock);
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if (ret < 0)
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{
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return ret;
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}
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/* Ensure that interrupts are disabled and we do not lose counts
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* if expiration occurs after read, but before setting counter
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* to zero
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*/
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intflags = enter_critical_section();
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/* Wait for an incoming event */
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if (timerfd_get_counter(dev) == 0)
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if (dev->counter == 0)
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{
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timerfd_waiter_sem_t sem;
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if (filep->f_oflags & O_NONBLOCK)
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{
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nxmutex_unlock(&dev->lock);
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leave_critical_section(intflags);
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return -EAGAIN;
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}
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@ -332,28 +301,21 @@ static ssize_t timerfd_read(FAR struct file *filep, FAR char *buffer,
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ret = timerfd_blocking_io(dev, &sem, &dev->rdsems);
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if (ret < 0)
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{
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leave_critical_section(intflags);
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nxsem_destroy(&sem.sem);
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return ret;
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}
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}
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while (timerfd_get_counter(dev) == 0);
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while (dev->counter == 0);
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nxsem_destroy(&sem.sem);
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}
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/* Device ready for read. Ensure that interrupts are disabled and we
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* do not lose counts if expiration occurs after read, but before setting
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* counter to zero
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*/
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intflags = spin_lock_irqsave(&dev->splock);
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*(FAR timerfd_t *)buffer = dev->counter;
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dev->counter = 0;
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spin_unlock_irqrestore(&dev->splock, intflags);
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leave_critical_section(intflags);
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nxmutex_unlock(&dev->lock);
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return sizeof(timerfd_t);
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}
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@ -362,17 +324,11 @@ static int timerfd_poll(FAR struct file *filep, FAR struct pollfd *fds,
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bool setup)
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{
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FAR struct timerfd_priv_s *dev = filep->f_priv;
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int ret;
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irqstate_t intflags;
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int ret = OK;
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int i;
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ret = nxmutex_lock(&dev->lock);
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if (ret < 0)
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{
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return ret;
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}
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ret = OK;
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intflags = enter_critical_section();
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if (!setup)
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{
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/* This is a request to tear down the poll. */
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@ -413,7 +369,7 @@ static int timerfd_poll(FAR struct file *filep, FAR struct pollfd *fds,
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/* Notify the POLLIN event if the counter is not zero */
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if (timerfd_get_counter(dev) > 0)
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if (dev->counter > 0)
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{
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#ifdef CONFIG_TIMER_FD_POLL
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poll_notify(dev->fds, CONFIG_TIMER_FD_NPOLLWAITERS, POLLIN);
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@ -421,22 +377,32 @@ static int timerfd_poll(FAR struct file *filep, FAR struct pollfd *fds,
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}
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out:
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nxmutex_unlock(&dev->lock);
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leave_critical_section(intflags);
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return ret;
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}
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#endif
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static void timerfd_timeout_work(FAR void *arg)
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static void timerfd_timeout(wdparm_t arg)
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{
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FAR struct timerfd_priv_s *dev = (FAR struct timerfd_priv_s *)arg;
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FAR timerfd_waiter_sem_t *cur_sem;
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int ret;
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irqstate_t intflags;
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ret = nxmutex_lock(&dev->lock);
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if (ret < 0)
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/* Disable interrupts to ensure that expiration counter is accessed
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* atomically
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*/
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intflags = enter_critical_section();
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/* Increment timer expiration counter */
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dev->counter++;
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/* If this is a repetitive timer, then restart the watchdog */
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if (dev->delay > 0)
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{
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wd_cancel(&dev->wdog);
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return;
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wd_start(&dev->wdog, dev->delay, timerfd_timeout, arg);
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}
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#ifdef CONFIG_TIMER_FD_POLL
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@ -455,34 +421,8 @@ static void timerfd_timeout_work(FAR void *arg)
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}
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dev->rdsems = NULL;
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nxmutex_unlock(&dev->lock);
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}
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static void timerfd_timeout(wdparm_t idev)
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{
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FAR struct timerfd_priv_s *dev = (FAR struct timerfd_priv_s *)idev;
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irqstate_t intflags;
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/* Disable interrupts to ensure that expiration counter is accessed
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* atomically
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*/
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intflags = spin_lock_irqsave(&dev->splock);
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/* Increment timer expiration counter */
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dev->counter++;
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work_queue(TIMER_FD_WORK, &dev->work, timerfd_timeout_work, dev, 0);
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/* If this is a repetitive timer, then restart the watchdog */
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if (dev->delay)
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{
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wd_start(&dev->wdog, dev->delay, timerfd_timeout, idev);
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}
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spin_unlock_irqrestore(&dev->splock, intflags);
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leave_critical_section(intflags);
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}
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/****************************************************************************
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@ -559,7 +499,7 @@ int timerfd_settime(int fd, int flags,
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goto errout;
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}
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if (flags && (flags & TFD_TIMER_ABSTIME) == 0)
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if ((flags & ~TFD_TIMER_ABSTIME) != 0)
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{
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ret = -EINVAL;
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goto errout;
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@ -583,6 +523,12 @@ int timerfd_settime(int fd, int flags,
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dev = (FAR struct timerfd_priv_s *)filep->f_priv;
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/* Disable interrupts here to ensure that expiration counter is accessed
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* atomicaly.
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*/
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intflags = enter_critical_section();
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if (old_value)
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{
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/* Get the number of ticks before the underlying watchdog expires */
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@ -595,22 +541,12 @@ int timerfd_settime(int fd, int flags,
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clock_ticks2time(dev->delay, &old_value->it_interval);
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}
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/* Disable interrupts here to ensure that expiration counter is accessed
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* atomicaly and timeout work is canceled with the same sequence
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*/
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intflags = spin_lock_irqsave(&dev->splock);
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/* Disarm the timer (in case the timer was already armed when
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* timerfd_settime() is called).
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*/
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wd_cancel(&dev->wdog);
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/* Cancel notification work */
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work_cancel(TIMER_FD_WORK, &dev->work);
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/* Clear expiration counter */
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dev->counter = 0;
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@ -621,25 +557,14 @@ int timerfd_settime(int fd, int flags,
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if (new_value->it_value.tv_sec <= 0 && new_value->it_value.tv_nsec <= 0)
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{
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spin_unlock_irqrestore(&dev->splock, intflags);
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leave_critical_section(intflags);
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return OK;
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}
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/* Setup up any repetitive timer */
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if (new_value->it_interval.tv_sec > 0 ||
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new_value->it_interval.tv_nsec > 0)
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{
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clock_time2ticks(&new_value->it_interval, &delay);
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/* REVISIT: Should delay be sclock_t? */
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dev->delay = (int)delay;
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}
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else
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{
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dev->delay = 0;
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}
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clock_time2ticks(&new_value->it_interval, &delay);
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dev->delay = delay;
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/* We need to disable timer interrupts through the following section so
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* that the system timer is stable.
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@ -674,17 +599,14 @@ int timerfd_settime(int fd, int flags,
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/* Then start the watchdog */
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if (delay > 0)
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ret = wd_start(&dev->wdog, delay, timerfd_timeout, (wdparm_t)dev);
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if (ret < 0)
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{
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ret = wd_start(&dev->wdog, delay, timerfd_timeout, (wdparm_t)dev);
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if (ret < 0)
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{
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spin_unlock_irqrestore(&dev->splock, intflags);
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goto errout;
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}
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leave_critical_section(intflags);
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goto errout;
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}
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spin_unlock_irqrestore(&dev->splock, intflags);
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leave_critical_section(intflags);
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return OK;
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errout:
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