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nuttx/drivers/pipes/pipe_common.c
Xiang Xiao 6a3c2aded6 Fix wait loop and void cast (#24) 
* Simplify EINTR/ECANCEL error handling

1. Add semaphore uninterruptible wait function
2 .Replace semaphore wait loop with a single uninterruptible wait
3. Replace all sem_xxx to nxsem_xxx

* Unify the void cast usage

1. Remove void cast for function because many place ignore the returned value witout cast
2. Replace void cast for variable with UNUSED macro
2020-01-02 10:54:43 -06:00

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/****************************************************************************
* drivers/pipes/pipe_common.c
*
* Copyright (C) 2008-2009, 2011, 2015-2016, 2018 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 <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <sched.h>
#include <semaphore.h>
#include <fcntl.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>
#ifdef CONFIG_DEBUG_FEATURES
# include <nuttx/arch.h>
#endif
#include <nuttx/kmalloc.h>
#include <nuttx/semaphore.h>
#include <nuttx/fs/fs.h>
#include <nuttx/fs/ioctl.h>
#include "pipe_common.h"
#ifdef CONFIG_PIPES
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* CONFIG_DEV_PIPEDUMP will dump the contents of each transfer into and out
* of the pipe.
*/
#ifdef CONFIG_DEV_PIPEDUMP
# define pipe_dumpbuffer(m,a,n) lib_dumpbuffer(m,a,n)
#else
# define pipe_dumpbuffer(m,a,n)
#endif
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static void pipecommon_semtake(sem_t *sem);
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: pipecommon_semtake
****************************************************************************/
static void pipecommon_semtake(FAR sem_t *sem)
{
nxsem_wait_uninterruptible(sem);
}
/****************************************************************************
* Name: pipecommon_pollnotify
****************************************************************************/
static void pipecommon_pollnotify(FAR struct pipe_dev_s *dev,
pollevent_t eventset)
{
int i;
if (eventset & POLLERR)
{
eventset &= ~(POLLOUT | POLLIN);
}
for (i = 0; i < CONFIG_DEV_PIPE_NPOLLWAITERS; i++)
{
FAR struct pollfd *fds = dev->d_fds[i];
if (fds)
{
fds->revents |= eventset & (fds->events | POLLERR | POLLHUP);
if ((fds->revents & (POLLOUT | POLLHUP)) == (POLLOUT | POLLHUP))
{
/* POLLOUT and POLLHUP are mutually exclusive. */
fds->revents &= ~POLLOUT;
}
if (fds->revents != 0)
{
finfo("Report events: %02x\n", fds->revents);
nxsem_post(fds->sem);
}
}
}
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: pipecommon_allocdev
****************************************************************************/
FAR struct pipe_dev_s *pipecommon_allocdev(size_t bufsize)
{
FAR struct pipe_dev_s *dev;
DEBUGASSERT(bufsize <= CONFIG_DEV_PIPE_MAXSIZE);
/* Allocate a private structure to manage the pipe */
dev = (FAR struct pipe_dev_s *)kmm_malloc(sizeof(struct pipe_dev_s));
if (dev)
{
/* Initialize the private structure */
memset(dev, 0, sizeof(struct pipe_dev_s));
nxsem_init(&dev->d_bfsem, 0, 1);
nxsem_init(&dev->d_rdsem, 0, 0);
nxsem_init(&dev->d_wrsem, 0, 0);
/* The read/write wait semaphores are used for signaling and, hence,
* should not have priority inheritance enabled.
*/
nxsem_setprotocol(&dev->d_rdsem, SEM_PRIO_NONE);
nxsem_setprotocol(&dev->d_wrsem, SEM_PRIO_NONE);
dev->d_bufsize = bufsize;
}
return dev;
}
/****************************************************************************
* Name: pipecommon_freedev
****************************************************************************/
void pipecommon_freedev(FAR struct pipe_dev_s *dev)
{
nxsem_destroy(&dev->d_bfsem);
nxsem_destroy(&dev->d_rdsem);
nxsem_destroy(&dev->d_wrsem);
kmm_free(dev);
}
/****************************************************************************
* Name: pipecommon_open
****************************************************************************/
int pipecommon_open(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct pipe_dev_s *dev = inode->i_private;
int sval;
int ret;
DEBUGASSERT(dev != NULL);
/* Make sure that we have exclusive access to the device structure. The
* nxsem_wait() call should fail only if we are awakened by a signal.
*/
ret = nxsem_wait(&dev->d_bfsem);
if (ret < 0)
{
ferr("ERROR: nxsem_wait failed: %d\n", ret);
return ret;
}
/* If this the first reference on the device, then allocate the buffer.
* In the case of policy 1, the buffer already be present when the pipe
* is first opened.
*/
if (inode->i_crefs == 1 && dev->d_buffer == NULL)
{
dev->d_buffer = (FAR uint8_t *)kmm_malloc(dev->d_bufsize);
if (!dev->d_buffer)
{
nxsem_post(&dev->d_bfsem);
return -ENOMEM;
}
}
/* If opened for writing, increment the count of writers on the pipe instance */
if ((filep->f_oflags & O_WROK) != 0)
{
dev->d_nwriters++;
/* If this this is the first writer, then the read semaphore indicates the
* number of readers waiting for the first writer. Wake them all up.
*/
if (dev->d_nwriters == 1)
{
while (nxsem_getvalue(&dev->d_rdsem, &sval) == 0 && sval < 0)
{
nxsem_post(&dev->d_rdsem);
}
}
}
/* If opened for reading, increment the count of reader on on the pipe instance */
if ((filep->f_oflags & O_RDOK) != 0)
{
dev->d_nreaders++;
}
/* If opened for read-only, then wait for either (1) at least one writer
* on the pipe (policy == 0), or (2) until there is buffered data to be
* read (policy == 1).
*/
sched_lock();
nxsem_post(&dev->d_bfsem);
if ((filep->f_oflags & O_RDWR) == O_RDONLY && /* Read-only */
dev->d_nwriters < 1 && /* No writers on the pipe */
dev->d_wrndx == dev->d_rdndx) /* Buffer is empty */
{
/* NOTE: d_rdsem is normally used when the read logic waits for more
* data to be written. But until the first writer has opened the
* pipe, the meaning is different: it is used prevent O_RDONLY open
* calls from returning until there is at least one writer on the pipe.
* This is required both by spec and also because it prevents
* subsequent read() calls from returning end-of-file because there is
* no writer on the pipe.
*/
ret = nxsem_wait(&dev->d_rdsem);
if (ret < 0)
{
/* The nxsem_wait() call should fail only if we are awakened by
* a signal.
*/
ferr("ERROR: nxsem_wait failed: %d\n", ret);
/* Immediately close the pipe that we just opened */
pipecommon_close(filep);
}
}
sched_unlock();
return ret;
}
/****************************************************************************
* Name: pipecommon_close
****************************************************************************/
int pipecommon_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct pipe_dev_s *dev = inode->i_private;
int sval;
DEBUGASSERT(dev && filep->f_inode->i_crefs > 0);
/* Make sure that we have exclusive access to the device structure.
* NOTE: close() is supposed to return EINTR if interrupted, however
* I've never seen anyone check that.
*/
pipecommon_semtake(&dev->d_bfsem);
/* Decrement the number of references on the pipe. Check if there are
* still outstanding references to the pipe.
*/
/* Check if the decremented inode reference count would go to zero */
if (inode->i_crefs > 1)
{
/* More references.. If opened for writing, decrement the count of
* writers on the pipe instance.
*/
if ((filep->f_oflags & O_WROK) != 0)
{
/* If there are no longer any writers on the pipe, then notify all of the
* waiting readers that they must return end-of-file.
*/
if (--dev->d_nwriters <= 0)
{
while (nxsem_getvalue(&dev->d_rdsem, &sval) == 0 && sval < 0)
{
nxsem_post(&dev->d_rdsem);
}
/* Inform poll readers that other end closed. */
pipecommon_pollnotify(dev, POLLHUP);
}
}
/* If opened for reading, decrement the count of readers on the pipe
* instance.
*/
if ((filep->f_oflags & O_RDOK) != 0)
{
if (--dev->d_nreaders <= 0)
{
if (PIPE_IS_POLICY_0(dev->d_flags))
{
/* Inform poll writers that other end closed. */
pipecommon_pollnotify(dev, POLLERR);
}
}
}
}
/* What is the buffer management policy? Do we free the buffer when the
* last client closes the pipe policy 0, or when the buffer becomes empty.
* In the latter case, the buffer data will remain valid and can be
* obtained when the pipe is re-opened.
*/
else if (PIPE_IS_POLICY_0(dev->d_flags) || dev->d_wrndx == dev->d_rdndx)
{
/* Policy 0 or the buffer is empty ... deallocate the buffer now. */
kmm_free(dev->d_buffer);
dev->d_buffer = NULL;
/* And reset all counts and indices */
dev->d_wrndx = 0;
dev->d_rdndx = 0;
dev->d_nwriters = 0;
dev->d_nreaders = 0;
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
/* If, in addition, we have been unlinked, then also need to free the
* device structure as well to prevent a memory leak.
*/
if (PIPE_IS_UNLINKED(dev->d_flags))
{
pipecommon_freedev(dev);
return OK;
}
#endif
}
nxsem_post(&dev->d_bfsem);
return OK;
}
/****************************************************************************
* Name: pipecommon_read
****************************************************************************/
ssize_t pipecommon_read(FAR struct file *filep, FAR char *buffer, size_t len)
{
FAR struct inode *inode = filep->f_inode;
FAR struct pipe_dev_s *dev = inode->i_private;
#ifdef CONFIG_DEV_PIPEDUMP
FAR uint8_t *start = (FAR uint8_t *)buffer;
#endif
ssize_t nread = 0;
int sval;
int ret;
DEBUGASSERT(dev);
if (len == 0)
{
return 0;
}
/* Make sure that we have exclusive access to the device structure */
ret = nxsem_wait(&dev->d_bfsem);
if (ret < 0)
{
return ret;
}
/* If the pipe is empty, then wait for something to be written to it */
while (dev->d_wrndx == dev->d_rdndx)
{
/* If O_NONBLOCK was set, then return EGAIN */
if (filep->f_oflags & O_NONBLOCK)
{
nxsem_post(&dev->d_bfsem);
return -EAGAIN;
}
/* If there are no writers on the pipe, then return end of file */
if (dev->d_nwriters <= 0)
{
nxsem_post(&dev->d_bfsem);
return 0;
}
/* Otherwise, wait for something to be written to the pipe */
sched_lock();
nxsem_post(&dev->d_bfsem);
ret = nxsem_wait(&dev->d_rdsem);
sched_unlock();
if (ret < 0 || (ret = nxsem_wait(&dev->d_bfsem)) < 0)
{
return ret;
}
}
/* Then return whatever is available in the pipe (which is at least one byte) */
nread = 0;
while ((size_t)nread < len && dev->d_wrndx != dev->d_rdndx)
{
*buffer++ = dev->d_buffer[dev->d_rdndx];
if (++dev->d_rdndx >= dev->d_bufsize)
{
dev->d_rdndx = 0;
}
nread++;
}
/* Notify all waiting writers that bytes have been removed from the buffer */
while (nxsem_getvalue(&dev->d_wrsem, &sval) == 0 && sval < 0)
{
nxsem_post(&dev->d_wrsem);
}
/* Notify all poll/select waiters that they can write to the FIFO */
pipecommon_pollnotify(dev, POLLOUT);
nxsem_post(&dev->d_bfsem);
pipe_dumpbuffer("From PIPE:", start, nread);
return nread;
}
/****************************************************************************
* Name: pipecommon_write
****************************************************************************/
ssize_t pipecommon_write(FAR struct file *filep, FAR const char *buffer,
size_t len)
{
FAR struct inode *inode = filep->f_inode;
FAR struct pipe_dev_s *dev = inode->i_private;
ssize_t nwritten = 0;
ssize_t last;
int nxtwrndx;
int sval;
int ret;
DEBUGASSERT(dev);
pipe_dumpbuffer("To PIPE:", (FAR uint8_t *)buffer, len);
/* Handle zero-length writes */
if (len == 0)
{
return 0;
}
/* REVISIT: "If all file descriptors referring to the read end of a pipe
* have been closed, then a write will cause a SIGPIPE signal to be
* generated for the calling process. If the calling process is ignoring
* this signal, then write(2) fails with the error EPIPE."
*/
if (dev->d_nreaders <= 0)
{
return -EPIPE;
}
/* At present, this method cannot be called from interrupt handlers. That
* is because it calls nxsem_wait (via pipecommon_semtake below) and
* nxsem_wait cannot be called from interrupt level. This actually
* happens fairly commonly IF [a-z]err() is called from interrupt handlers
* and stdout is being redirected via a pipe. In that case, the debug
* output will try to go out the pipe (interrupt handlers should use the
* _err() APIs).
*
* On the other hand, it would be very valuable to be able to feed the pipe
* from an interrupt handler! TODO: Consider disabling interrupts instead
* of taking semaphores so that pipes can be written from interrupt handlers
*/
DEBUGASSERT(up_interrupt_context() == false);
/* Make sure that we have exclusive access to the device structure */
ret = nxsem_wait(&dev->d_bfsem);
if (ret < 0)
{
return ret;
}
/* Loop until all of the bytes have been written */
last = 0;
for (; ; )
{
/* Calculate the write index AFTER the next byte is written */
nxtwrndx = dev->d_wrndx + 1;
if (nxtwrndx >= dev->d_bufsize)
{
nxtwrndx = 0;
}
/* Would the next write overflow the circular buffer? */
if (nxtwrndx != dev->d_rdndx)
{
/* No... copy the byte */
dev->d_buffer[dev->d_wrndx] = *buffer++;
dev->d_wrndx = nxtwrndx;
/* Is the write complete? */
nwritten++;
if ((size_t)nwritten >= len)
{
/* Yes.. Notify all of the waiting readers that more data is available */
while (nxsem_getvalue(&dev->d_rdsem, &sval) == 0 && sval < 0)
{
nxsem_post(&dev->d_rdsem);
}
/* Notify all poll/select waiters that they can read from the FIFO */
pipecommon_pollnotify(dev, POLLIN);
/* Return the number of bytes written */
nxsem_post(&dev->d_bfsem);
return len;
}
}
else
{
/* There is not enough room for the next byte. Was anything written in this pass? */
if (last < nwritten)
{
/* Yes.. Notify all of the waiting readers that more data is available */
while (nxsem_getvalue(&dev->d_rdsem, &sval) == 0 && sval < 0)
{
nxsem_post(&dev->d_rdsem);
}
/* Notify all poll/select waiters that they can read from the FIFO */
pipecommon_pollnotify(dev, POLLIN);
}
last = nwritten;
/* If O_NONBLOCK was set, then return partial bytes written or EGAIN */
if (filep->f_oflags & O_NONBLOCK)
{
if (nwritten == 0)
{
nwritten = -EAGAIN;
}
nxsem_post(&dev->d_bfsem);
return nwritten;
}
/* There is more to be written.. wait for data to be removed from the pipe */
sched_lock();
nxsem_post(&dev->d_bfsem);
pipecommon_semtake(&dev->d_wrsem);
sched_unlock();
pipecommon_semtake(&dev->d_bfsem);
}
}
}
/****************************************************************************
* Name: pipecommon_poll
****************************************************************************/
int pipecommon_poll(FAR struct file *filep, FAR struct pollfd *fds,
bool setup)
{
FAR struct inode *inode = filep->f_inode;
FAR struct pipe_dev_s *dev = inode->i_private;
pollevent_t eventset;
pipe_ndx_t nbytes;
int ret = OK;
int i;
DEBUGASSERT(dev && fds);
/* Are we setting up the poll? Or tearing it down? */
pipecommon_semtake(&dev->d_bfsem);
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_DEV_PIPE_NPOLLWAITERS; i++)
{
/* Find an available slot */
if (!dev->d_fds[i])
{
/* Bind the poll structure and this slot */
dev->d_fds[i] = fds;
fds->priv = &dev->d_fds[i];
break;
}
}
if (i >= CONFIG_DEV_PIPE_NPOLLWAITERS)
{
fds->priv = NULL;
ret = -EBUSY;
goto errout;
}
/* Should immediately notify on any of the requested events?
* First, determine how many bytes are in the buffer
*/
if (dev->d_wrndx >= dev->d_rdndx)
{
nbytes = dev->d_wrndx - dev->d_rdndx;
}
else
{
nbytes = dev->d_bufsize + dev->d_wrndx - dev->d_rdndx;
}
/* Notify the POLLOUT event if the pipe is not full, but only if
* there is readers.
*/
eventset = 0;
if ((filep->f_oflags & O_WROK) && (nbytes < (dev->d_bufsize - 1)))
{
eventset |= POLLOUT;
}
/* Notify the POLLIN event if the pipe is not empty */
if ((filep->f_oflags & O_RDOK) && (nbytes > 0))
{
eventset |= POLLIN;
}
/* Notify the POLLHUP event if the pipe is empty and no writers */
if (nbytes == 0 && dev->d_nwriters <= 0)
{
eventset |= POLLHUP;
}
/* Change POLLOUT to POLLERR, if no readers and policy 0. */
if ((eventset | POLLOUT) &&
PIPE_IS_POLICY_0(dev->d_flags) &&
dev->d_nreaders <= 0)
{
eventset |= POLLERR;
}
if (eventset)
{
pipecommon_pollnotify(dev, eventset);
}
}
else
{
/* This is a request to tear down the poll. */
FAR struct pollfd **slot = (FAR struct pollfd **)fds->priv;
#ifdef CONFIG_DEBUG_FEATURES
if (!slot)
{
ret = -EIO;
goto errout;
}
#endif
/* Remove all memory of the poll setup */
*slot = NULL;
fds->priv = NULL;
}
errout:
nxsem_post(&dev->d_bfsem);
return ret;
}
/****************************************************************************
* Name: pipecommon_ioctl
****************************************************************************/
int pipecommon_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode = filep->f_inode;
FAR struct pipe_dev_s *dev = inode->i_private;
int ret = -EINVAL;
#ifdef CONFIG_DEBUG_FEATURES
/* Some sanity checking */
if (dev == NULL)
{
return -EBADF;
}
#endif
pipecommon_semtake(&dev->d_bfsem);
switch (cmd)
{
case PIPEIOC_POLICY:
{
if (arg != 0)
{
PIPE_POLICY_1(dev->d_flags);
}
else
{
PIPE_POLICY_0(dev->d_flags);
}
ret = OK;
}
break;
case FIONWRITE: /* Number of bytes waiting in send queue */
case FIONREAD: /* Number of bytes available for reading */
{
int count;
/* Determine the number of bytes written to the buffer. This is,
* of course, also the number of bytes that may be read from the
* buffer.
*
* d_rdndx - index to remove next byte from the buffer
* d_wrndx - Index to next location to add a byte to the buffer.
*/
if (dev->d_wrndx < dev->d_rdndx)
{
count = (dev->d_bufsize - dev->d_rdndx) + dev->d_wrndx;
}
else
{
count = dev->d_wrndx - dev->d_rdndx;
}
*(FAR int *)((uintptr_t)arg) = count;
ret = 0;
}
break;
/* Free space in buffer */
case FIONSPACE:
{
int count;
/* Determine the number of bytes free in the buffer.
*
* d_rdndx - index to remove next byte from the buffer
* d_wrndx - Index to next location to add a byte to the buffer.
*/
if (dev->d_wrndx < dev->d_rdndx)
{
count = (dev->d_rdndx - dev->d_wrndx) - 1;
}
else
{
count = ((dev->d_bufsize - dev->d_wrndx) + dev->d_rdndx) - 1;
}
*(FAR int *)((uintptr_t)arg) = count;
ret = 0;
}
break;
default:
break;
}
nxsem_post(&dev->d_bfsem);
return ret;
}
/****************************************************************************
* Name: pipecommon_unlink
****************************************************************************/
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
int pipecommon_unlink(FAR struct inode *inode)
{
FAR struct pipe_dev_s *dev;
DEBUGASSERT(inode && inode->i_private);
dev = (FAR struct pipe_dev_s *)inode->i_private;
/* Mark the pipe unlinked */
PIPE_UNLINK(dev->d_flags);
/* Are the any open references to the driver? */
if (inode->i_crefs == 1)
{
/* No.. free the buffer (if there is one) */
if (dev->d_buffer)
{
kmm_free(dev->d_buffer);
}
/* And free the device structure. */
pipecommon_freedev(dev);
}
return OK;
}
#endif
#endif /* CONFIG_PIPES */
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