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nuttx/graphics/nxterm/nxterm_kbdin.c
dongjiuzhu d452a05910 pollnotify: we should send poll events before semaphore incrementes. 
There is a good case on sim platform:
When we input some cmd and click enter key to start application in terminal,
this context will change to application from IDLE loop. Althrough entey key '\r'
has been received to recv buffer and complete post semaphore of reader, but
pollnotify may not be called because context change. So when application run
poll function, because no events happend and poll enter wait, context will
again change to IDLE loop, this pollnotify of IDLE loop will run to send poll
events, poll function of applicaton will wake up. It's wrong!

Change-Id: I812a889f2e90781a9c3cb4b0251cccc4d32bebd1
Signed-off-by: dongjiuzhu <dongjiuzhu1@xiaomi.com>
2020-10-26 08:27:09 -03:00

476 lines
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/****************************************************************************
* nuttx/graphics/nxterm/nxterm_kbdin.c
*
* Copyright (C) 2012, 2016 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <fcntl.h>
#include <sched.h>
#include <assert.h>
#include <poll.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/irq.h>
#include "nxterm.h"
#ifdef CONFIG_NXTERM_NXKBDIN
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: nxterm_pollnotify
****************************************************************************/
static void nxterm_pollnotify(FAR struct nxterm_state_s *priv,
pollevent_t eventset)
{
FAR struct pollfd *fds;
irqstate_t flags;
int i;
/* This function may be called from an interrupt handler */
for (i = 0; i < CONFIG_NXTERM_NPOLLWAITERS; i++)
{
flags = enter_critical_section();
fds = priv->fds[i];
if (fds)
{
fds->revents |= (fds->events & eventset);
if (fds->revents != 0)
{
nxsem_post(fds->sem);
}
}
leave_critical_section(flags);
}
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nxterm_read
*
* Description:
* The optional NxTerm read method
*
****************************************************************************/
ssize_t nxterm_read(FAR struct file *filep, FAR char *buffer, size_t len)
{
FAR struct nxterm_state_s *priv;
ssize_t nread;
char ch;
int ret;
/* Recover our private state structure */
DEBUGASSERT(filep && filep->f_priv);
priv = (FAR struct nxterm_state_s *)filep->f_priv;
/* Get exclusive access to the driver structure */
ret = nxterm_semwait(priv);
if (ret < 0)
{
gerr("ERROR: nxterm_semwait failed\n");
return ret;
}
/* Loop until something is read */
for (nread = 0; nread < len; )
{
/* Get the next byte from the buffer */
if (priv->head == priv->tail)
{
/* The circular buffer is empty. Did we read anything? */
if (nread > 0)
{
/* Yes.. break out to return what we have. */
break;
}
/* If the driver was opened with O_NONBLOCK option, then
* don't wait. Just return EGAIN.
*/
if (filep->f_oflags & O_NONBLOCK)
{
nread = -EAGAIN;
break;
}
/* Otherwise, wait for something to be written to the circular
* buffer. Increment the number of waiters so that the
* nxterm_write() will not that it needs to post the semaphore
* to wake us up.
*/
sched_lock();
priv->nwaiters++;
nxterm_sempost(priv);
/* We may now be pre-empted! But that should be okay because we
* have already incremented nwaiters. Pre-emption is disabled
* but will be re-enabled while we are waiting.
*/
ret = nxsem_wait(&priv->waitsem);
/* Pre-emption will be disabled when we return. So the
* decrementing nwaiters here is safe.
*/
priv->nwaiters--;
sched_unlock();
/* Did we successfully get the waitsem? */
if (ret >= 0)
{
/* Yes... then retake the mutual exclusion semaphore */
ret = nxterm_semwait(priv);
}
/* Was the semaphore wait successful? Did we successful re-take the
* mutual exclusion semaphore?
*/
if (ret < 0)
{
/* No.. One of the two nxterm_semwait's failed. */
gerr("ERROR: nxterm_semwait failed\n");
/* Were we awakened by a signal? Did we read anything before
* we received the signal?
*/
if (ret != -EINTR || nread >= 0)
{
/* Yes.. return the error. */
nread = ret;
}
/* Break out to return what we have. Note, we can't exactly
* "break" out because whichever error occurred, we do not hold
* the exclusion semaphore.
*/
goto errout_without_sem;
}
}
else
{
/* The circular buffer is not empty, get the next byte from the
* tail index.
*/
ch = priv->rxbuffer[priv->tail];
/* Increment the tail index and re-enable interrupts */
if (++priv->tail >= CONFIG_NXTERM_KBDBUFSIZE)
{
priv->tail = 0;
}
/* Add the character to the user buffer */
buffer[nread] = ch;
nread++;
}
}
/* Relinquish the mutual exclusion semaphore */
nxterm_sempost(priv);
/* Notify all poll/select waiters that they can write to the FIFO */
errout_without_sem:
if (nread > 0)
{
nxterm_pollnotify(priv, POLLOUT);
}
/* Return the number of characters actually read */
return nread;
}
/****************************************************************************
* Name: nxterm_poll
****************************************************************************/
int nxterm_poll(FAR struct file *filep, FAR struct pollfd *fds, bool setup)
{
FAR struct inode *inode = filep->f_inode;
FAR struct nxterm_state_s *priv;
pollevent_t eventset;
int ret;
int i;
/* Some sanity checking */
DEBUGASSERT(inode && inode->i_private);
priv = inode->i_private;
/* Get exclusive access to the driver structure */
ret = nxterm_semwait(priv);
if (ret < 0)
{
gerr("ERROR: nxterm_semwait failed\n");
return ret;
}
/* Are we setting up the poll? Or tearing it down? */
if (setup)
{
/* This is a request to set up the poll. Find an available
* slot for the poll structure reference
*/
for (i = 0; i < CONFIG_NXTERM_NPOLLWAITERS; i++)
{
/* Find an available slot */
if (!priv->fds[i])
{
/* Bind the poll structure and this slot */
priv->fds[i] = fds;
fds->priv = &priv->fds[i];
break;
}
}
if (i >= CONFIG_NXTERM_NPOLLWAITERS)
{
gerr("ERROR: Too many poll waiters\n");
fds->priv = NULL;
ret = -EBUSY;
goto errout;
}
/* Should immediately notify on any of the requested events?
* This driver is always available for transmission.
*/
eventset = POLLOUT;
/* Check if the receive buffer is empty */
if (priv->head != priv->tail)
{
eventset |= POLLIN;
}
if (eventset)
{
nxterm_pollnotify(priv, eventset);
}
}
else if (fds->priv)
{
/* This is a request to tear down the poll. */
struct pollfd **slot = (struct pollfd **)fds->priv;
#ifdef CONFIG_DEBUG_GRAPHICS
if (!slot)
{
gerr("ERROR: No slot\n");
ret = -EIO;
goto errout;
}
#endif
/* Remove all memory of the poll setup */
*slot = NULL;
fds->priv = NULL;
}
errout:
nxterm_sempost(priv);
return ret;
}
/****************************************************************************
* Name: nxterm_kbdin
*
* Description:
* This function should be driven by the window kbdin callback function
* (see nx.h). When the NxTerm is the top window and keyboard input is
* received on the top window, that window callback should be directed to
* this function. This function will buffer the keyboard data and makE
* it available to the NxTerm as stdin.
*
* If CONFIG_NXTERM_NXKBDIN is not selected, then the NxTerm will
* receive its input from stdin (/dev/console). This works great but
* cannot be shared between different windows. Chaos will ensue if you
* try to support multiple NxTerm windows without CONFIG_NXTERM_NXKBDIN
*
* Input Parameters:
* handle - A handle previously returned by nx_register, nxtk_register, or
* nxtool_register.
* buffer - The array of characters
* buflen - The number of characters that are available in buffer[]
*
* Returned Value:
* None
*
****************************************************************************/
void nxterm_kbdin(NXTERM handle, FAR const uint8_t *buffer, uint8_t buflen)
{
FAR struct nxterm_state_s *priv;
ssize_t nwritten;
int nexthead;
char ch;
int ret;
ginfo("buflen=%d\n");
DEBUGASSERT(handle);
/* Get the reference to the driver structure from the handle */
priv = (FAR struct nxterm_state_s *)handle;
/* Get exclusive access to the driver structure */
ret = nxterm_semwait(priv);
if (ret < 0)
{
gerr("ERROR: nxterm_semwait failed\n");
return;
}
/* Loop until all of the bytes have been written. This function may be
* called from an interrupt handler! Semaphores cannot be used!
*
* The write logic only needs to modify the head index. Therefore,
* there is a difference in the way that head and tail are protected:
* tail is protected with a semaphore; tail is protected by disabling
* interrupts.
*/
for (nwritten = 0; nwritten < buflen; nwritten++)
{
/* Add the next character */
ch = buffer[nwritten];
/* Calculate the write index AFTER the next byte is add to the ring
* buffer
*/
nexthead = priv->head + 1;
if (nexthead >= CONFIG_NXTERM_KBDBUFSIZE)
{
nexthead = 0;
}
/* Would the next write overflow the circular buffer? */
if (nexthead == priv->tail)
{
/* Yes... Return an indication that nothing was saved in
* the buffer.
*/
gerr("ERROR: Keyboard data overrun\n");
break;
}
/* No... copy the byte */
priv->rxbuffer[priv->head] = ch;
priv->head = nexthead;
}
/* Was anything written? */
if (nwritten > 0)
{
int i;
/* Are there threads waiting for read data? */
sched_lock();
/* Notify all poll/select waiters that they can read from the FIFO */
nxterm_pollnotify(priv, POLLIN);
for (i = 0; i < priv->nwaiters; i++)
{
/* Yes.. Notify all of the waiting readers that more data is
* available
*/
nxsem_post(&priv->waitsem);
}
sched_unlock();
}
nxterm_sempost(priv);
}
#endif /* CONFIG_NXTERM_NXKBDIN */
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