forked from nuttx/nuttx-update
input/buttons: Always protect the resource by critical section
it's wrong to protect the resource by bu_exclsem in some case and critical section in others Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
This commit is contained in:
Xiang Xiao
Petro Karashchenko
parent
f884e647ec
commit
b690262aac
1 changed files with 36 additions and 127 deletions
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@ -60,7 +60,6 @@ struct btn_upperhalf_s
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FAR const struct btn_lowerhalf_s *bu_lower;
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btn_buttonset_t bu_sample; /* Last sampled button states */
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sem_t bu_exclsem; /* Supports exclusive access to the device */
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/* The following is a singly linked list of open references to the
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* button device.
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@ -77,10 +76,6 @@ struct btn_open_s
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FAR struct btn_open_s *bo_flink;
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/* The following will be true if we are closing */
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volatile bool bo_closing;
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/* Button event notification information */
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pid_t bo_pid;
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@ -103,11 +98,6 @@ struct btn_open_s
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* Private Function Prototypes
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****************************************************************************/
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/* Semaphore helpers */
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static inline int btn_takesem(sem_t *sem);
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#define btn_givesem(s) nxsem_post(s);
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/* Sampling and Interrupt handling */
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static void btn_enable(FAR struct btn_upperhalf_s *priv);
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@ -153,15 +143,6 @@ static const struct file_operations btn_fops =
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: btn_takesem
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****************************************************************************/
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static inline int btn_takesem(sem_t *sem)
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{
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return nxsem_wait(sem);
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}
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/****************************************************************************
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* Name: btn_enable
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****************************************************************************/
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@ -249,18 +230,11 @@ static void btn_sample(FAR struct btn_upperhalf_s *priv)
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btn_buttonset_t change;
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btn_buttonset_t press;
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btn_buttonset_t release;
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irqstate_t flags;
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int i;
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DEBUGASSERT(priv && priv->bu_lower);
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lower = priv->bu_lower;
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/* This routine is called both task level and interrupt level, so
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* interrupts must be disabled.
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*/
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flags = enter_critical_section();
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/* Sample the new button state */
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DEBUGASSERT(lower->bl_buttons);
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@ -322,7 +296,6 @@ static void btn_sample(FAR struct btn_upperhalf_s *priv)
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}
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priv->bu_sample = sample;
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leave_critical_section(flags);
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}
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/****************************************************************************
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@ -336,38 +309,30 @@ static int btn_open(FAR struct file *filep)
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FAR struct btn_open_s *opriv;
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FAR const struct btn_lowerhalf_s *lower;
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btn_buttonset_t supported;
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int ret;
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irqstate_t flags;
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DEBUGASSERT(filep && filep->f_inode);
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inode = filep->f_inode;
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DEBUGASSERT(inode->i_private);
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priv = (FAR struct btn_upperhalf_s *)inode->i_private;
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/* Get exclusive access to the driver structure */
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ret = btn_takesem(&priv->bu_exclsem);
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if (ret < 0)
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{
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ierr("ERROR: btn_takesem failed: %d\n", ret);
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return ret;
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}
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/* Allocate a new open structure */
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opriv = (FAR struct btn_open_s *)kmm_zalloc(sizeof(struct btn_open_s));
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if (!opriv)
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{
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ierr("ERROR: Failed to allocate open structure\n");
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ret = -ENOMEM;
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goto errout_with_sem;
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return -ENOMEM;
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}
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/* Initialize the open structure */
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lower = priv->bu_lower;
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DEBUGASSERT(lower && lower->bl_supported);
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supported = lower->bl_supported(lower);
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flags = enter_critical_section();
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supported = lower->bl_supported(lower);
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opriv->bo_pollevents.bp_press = supported;
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opriv->bo_pollevents.bp_release = supported;
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@ -379,15 +344,13 @@ static int btn_open(FAR struct file *filep)
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/* Attach the open structure to the file structure */
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filep->f_priv = (FAR void *)opriv;
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ret = OK;
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/* Enable/disable interrupt handling */
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btn_enable(priv);
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errout_with_sem:
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btn_givesem(&priv->bu_exclsem);
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return ret;
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leave_critical_section(flags);
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return OK;
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}
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/****************************************************************************
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@ -402,8 +365,6 @@ static int btn_close(FAR struct file *filep)
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FAR struct btn_open_s *curr;
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FAR struct btn_open_s *prev;
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irqstate_t flags;
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bool closing;
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int ret;
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DEBUGASSERT(filep && filep->f_priv && filep->f_inode);
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opriv = filep->f_priv;
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@ -411,36 +372,9 @@ static int btn_close(FAR struct file *filep)
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DEBUGASSERT(inode->i_private);
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priv = (FAR struct btn_upperhalf_s *)inode->i_private;
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/* Handle an improbable race conditions with the following atomic test
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* and set.
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*
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* This is actually a pretty feeble attempt to handle this. The
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* improbable race condition occurs if two different threads try to
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* close the button driver at the same time. The rule: don't do
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* that! It is feeble because we do not really enforce stale pointer
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* detection anyway.
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*/
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flags = enter_critical_section();
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closing = opriv->bo_closing;
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opriv->bo_closing = true;
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leave_critical_section(flags);
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if (closing)
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{
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/* Another thread is doing the close */
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return OK;
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}
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/* Get exclusive access to the driver structure */
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ret = btn_takesem(&priv->bu_exclsem);
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if (ret < 0)
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{
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ierr("ERROR: btn_takesem failed: %d\n", ret);
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return ret;
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}
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flags = enter_critical_section();
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/* Find the open structure in the list of open structures for the device */
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@ -452,8 +386,8 @@ static int btn_close(FAR struct file *filep)
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if (!curr)
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{
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ierr("ERROR: Failed to find open entry\n");
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ret = -ENOENT;
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goto errout_with_exclsem;
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leave_critical_section(flags);
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return -ENOENT;
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}
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/* Remove the structure from the device */
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@ -467,6 +401,12 @@ static int btn_close(FAR struct file *filep)
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priv->bu_open = opriv->bo_flink;
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}
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/* Enable/disable interrupt handling */
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btn_enable(priv);
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leave_critical_section(flags);
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/* Cancel any pending notification */
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nxsig_cancel_notification(&opriv->bo_work);
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@ -474,15 +414,7 @@ static int btn_close(FAR struct file *filep)
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/* And free the open structure */
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kmm_free(opriv);
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/* Enable/disable interrupt handling */
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btn_enable(priv);
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ret = OK;
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errout_with_exclsem:
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btn_givesem(&priv->bu_exclsem);
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return ret;
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return OK;
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}
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/****************************************************************************
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@ -496,7 +428,7 @@ static ssize_t btn_read(FAR struct file *filep, FAR char *buffer,
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FAR struct btn_open_s *opriv;
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FAR struct btn_upperhalf_s *priv;
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FAR const struct btn_lowerhalf_s *lower;
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int ret;
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irqstate_t flags;
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DEBUGASSERT(filep && filep->f_inode);
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opriv = filep->f_priv;
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@ -518,12 +450,7 @@ static ssize_t btn_read(FAR struct file *filep, FAR char *buffer,
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/* Get exclusive access to the driver structure */
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ret = btn_takesem(&priv->bu_exclsem);
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if (ret < 0)
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{
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ierr("ERROR: btn_takesem failed: %d\n", ret);
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return ret;
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}
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flags = enter_critical_section();
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/* Read and return the current state of the buttons */
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@ -532,7 +459,7 @@ static ssize_t btn_read(FAR struct file *filep, FAR char *buffer,
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*(FAR btn_buttonset_t *)buffer = lower->bl_buttons(lower);
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opriv->bo_pending = false;
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btn_givesem(&priv->bu_exclsem);
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leave_critical_section(flags);
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return (ssize_t)sizeof(btn_buttonset_t);
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}
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@ -546,6 +473,7 @@ static ssize_t btn_write(FAR struct file *filep, FAR const char *buffer,
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FAR struct inode *inode;
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FAR struct btn_upperhalf_s *priv;
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FAR const struct btn_lowerhalf_s *lower;
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irqstate_t flags;
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int ret;
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DEBUGASSERT(filep && filep->f_inode);
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@ -567,12 +495,7 @@ static ssize_t btn_write(FAR struct file *filep, FAR const char *buffer,
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/* Get exclusive access to the driver structure */
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ret = btn_takesem(&priv->bu_exclsem);
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if (ret < 0)
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{
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ierr("ERROR: btn_takesem failed: %d\n", ret);
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return ret;
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}
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flags = enter_critical_section();
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/* Write the current state of the buttons */
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@ -587,7 +510,7 @@ static ssize_t btn_write(FAR struct file *filep, FAR const char *buffer,
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ret = -ENOSYS;
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}
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btn_givesem(&priv->bu_exclsem);
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leave_critical_section(flags);
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return (ssize_t)ret;
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}
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@ -601,7 +524,8 @@ static int btn_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
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FAR struct btn_upperhalf_s *priv;
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FAR struct btn_open_s *opriv;
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FAR const struct btn_lowerhalf_s *lower;
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int ret;
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irqstate_t flags;
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int ret = OK;
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DEBUGASSERT(filep && filep->f_priv && filep->f_inode);
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opriv = filep->f_priv;
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@ -611,12 +535,7 @@ static int btn_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
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/* Get exclusive access to the driver structure */
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ret = btn_takesem(&priv->bu_exclsem);
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if (ret < 0)
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{
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ierr("ERROR: btn_takesem failed: %d\n", ret);
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return ret;
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}
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flags = enter_critical_section();
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/* Handle the ioctl command */
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@ -717,7 +636,7 @@ static int btn_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
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break;
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}
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btn_givesem(&priv->bu_exclsem);
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leave_critical_section(flags);
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return ret;
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}
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@ -731,7 +650,8 @@ static int btn_poll(FAR struct file *filep, FAR struct pollfd *fds,
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FAR struct inode *inode;
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FAR struct btn_upperhalf_s *priv;
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FAR struct btn_open_s *opriv;
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int ret;
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irqstate_t flags;
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int ret = OK;
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int i;
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DEBUGASSERT(filep && filep->f_priv && filep->f_inode);
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@ -742,12 +662,7 @@ static int btn_poll(FAR struct file *filep, FAR struct pollfd *fds,
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/* Get exclusive access to the driver structure */
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ret = btn_takesem(&priv->bu_exclsem);
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if (ret < 0)
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{
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ierr("ERROR: btn_takesem failed: %d\n", ret);
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return ret;
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}
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flags = enter_critical_section();
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/* Are we setting up the poll? Or tearing it down? */
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@ -789,7 +704,7 @@ static int btn_poll(FAR struct file *filep, FAR struct pollfd *fds,
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ierr("ERROR: Too many poll waiters\n");
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fds->priv = NULL;
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ret = -EBUSY;
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goto errout_with_dusem;
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goto errout;
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}
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}
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else if (fds->priv)
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@ -803,7 +718,7 @@ static int btn_poll(FAR struct file *filep, FAR struct pollfd *fds,
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{
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ierr("ERROR: Poll slot not found\n");
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ret = -EIO;
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goto errout_with_dusem;
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goto errout;
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}
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#endif
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@ -813,9 +728,10 @@ static int btn_poll(FAR struct file *filep, FAR struct pollfd *fds,
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fds->priv = NULL;
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}
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errout_with_dusem:
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btn_enable(priv);
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btn_givesem(&priv->bu_exclsem);
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errout:
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leave_critical_section(flags);
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return ret;
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}
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@ -855,7 +771,6 @@ int btn_register(FAR const char *devname,
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priv = (FAR struct btn_upperhalf_s *)
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kmm_zalloc(sizeof(struct btn_upperhalf_s));
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if (!priv)
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{
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ierr("ERROR: Failed to allocate device structure\n");
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@ -870,7 +785,6 @@ int btn_register(FAR const char *devname,
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/* Initialize the new button driver instance */
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priv->bu_lower = lower;
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nxsem_init(&priv->bu_exclsem, 0, 1);
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DEBUGASSERT(lower->bl_buttons);
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priv->bu_sample = lower->bl_buttons(lower);
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@ -881,13 +795,8 @@ int btn_register(FAR const char *devname,
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if (ret < 0)
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{
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ierr("ERROR: register_driver failed: %d\n", ret);
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goto errout_with_priv;
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kmm_free(priv);
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}
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return OK;
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errout_with_priv:
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nxsem_destroy(&priv->bu_exclsem);
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kmm_free(priv);
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return ret;
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}
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