forked from nuttx/nuttx-update
Pipes/FIFOs: Implement the unlink method. If the pipe/FIFO is unlinked, it will marked the pipe/FIFO as unliked. If/when all open references to the driver are closed, all of the driver resources will be freed.
This commit is contained in:
Gregory Nutt
parent
05e82a88a7
commit
39a5238c43
4 changed files with 116 additions and 43 deletions
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@ -1,7 +1,7 @@
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/****************************************************************************
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* drivers/pipes/fifo.c
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*
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* Copyright (C) 2008-2009, 2014 Gregory Nutt. All rights reserved.
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* Copyright (C) 2008-2009, 2014-2015 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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@ -73,10 +73,11 @@ static const struct file_operations fifo_fops =
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pipecommon_read, /* read */
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pipecommon_write, /* write */
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0, /* seek */
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pipecommon_ioctl /* ioctl */
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pipecommon_ioctl, /* ioctl */
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#ifndef CONFIG_DISABLE_POLL
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, pipecommon_poll /* poll */
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pipecommon_poll, /* poll */
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#endif
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pipecommon_unlink /* unlink */
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};
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/****************************************************************************
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@ -92,15 +93,15 @@ static const struct file_operations fifo_fops =
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*
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* Description:
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* mkfifo() makes a FIFO device driver file with name 'pathname.' Unlike
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* Linux, a NuttX FIFO is not a special file type but simply a device driver
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* instance. 'mode' specifies the FIFO's permissions.
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* Linux, a NuttX FIFO is not a special file type but simply a device
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* driver instance. 'mode' specifies the FIFO's permissions.
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*
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* Once the FIFO has been created by mkfifo(), any thread can open it for
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* reading or writing, in the same way as an ordinary file. However, it must
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* have been opened from both reading and writing before input or output
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* can be performed. This FIFO implementation will block all attempts to
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* open a FIFO read-only until at least one thread has opened the FIFO for
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* writing.
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* reading or writing, in the same way as an ordinary file. However, it
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* must have been opened from both reading and writing before input or
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* output can be performed. This FIFO implementation will block all
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* attempts to open a FIFO read-only until at least one thread has opened
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* the FIFO for writing.
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*
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* If all threads that write to the FIFO have closed, subsequent calls to
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* read() on the FIFO will return 0 (end-of-file).
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@ -1,7 +1,7 @@
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/****************************************************************************
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* drivers/pipes/pipe.c
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*
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* Copyright (C) 2008-2009 Gregory Nutt. All rights reserved.
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* Copyright (C) 2008-2009, 2015 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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@ -82,10 +82,11 @@ static const struct file_operations pipe_fops =
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pipecommon_read, /* read */
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pipecommon_write, /* write */
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0, /* seek */
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pipecommon_ioctl /* ioctl */
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pipecommon_ioctl, /* ioctl */
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#ifndef CONFIG_DISABLE_POLL
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, pipecommon_poll /* poll */
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pipecommon_poll, /* poll */
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#endif
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pipecommon_unlink /* unlink */
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};
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static sem_t g_pipesem = SEM_INITIALIZER(1);
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@ -124,7 +125,9 @@ static inline int pipe_allocate(void)
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static inline void pipe_free(int pipeno)
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{
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int ret = sem_wait(&g_pipesem);
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int ret;
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ret = sem_wait(&g_pipesem);
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if (ret == 0)
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{
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g_pipeset &= ~(1 << pipeno);
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@ -138,17 +141,11 @@ static inline void pipe_free(int pipeno)
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static int pipe_close(FAR struct file *filep)
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{
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struct inode *inode = filep->f_inode;
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struct pipe_dev_s *dev = inode->i_private;
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int ret;
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FAR struct inode *inode = filep->f_inode;
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FAR struct pipe_dev_s *dev = inode->i_private;
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int ret;
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/* Some sanity checking */
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#if CONFIG_DEBUG
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if (!dev)
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{
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return -EBADF;
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}
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#endif
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DEBUGASSERT(dev);
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/* Perform common close operations */
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@ -171,8 +168,8 @@ static int pipe_close(FAR struct file *filep)
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* Name: pipe
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*
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* Description:
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* pipe() creates a pair of file descriptors, pointing to a pipe inode, and
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* places them in the array pointed to by 'fd'. fd[0] is for reading,
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* pipe() creates a pair of file descriptors, pointing to a pipe inode,
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* and places them in the array pointed to by 'fd'. fd[0] is for reading,
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* fd[1] is for writing.
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*
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* Inputs:
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@ -187,7 +184,7 @@ static int pipe_close(FAR struct file *filep)
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int pipe(int fd[2])
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{
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struct pipe_dev_s *dev = NULL;
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FAR struct pipe_dev_s *dev = NULL;
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char devname[16];
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int pipeno;
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int err;
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@ -272,15 +269,19 @@ int pipe(int fd[2])
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errout_with_wrfd:
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close(fd[1]);
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errout_with_driver:
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unregister_driver(devname);
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errout_with_dev:
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if (dev)
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{
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pipecommon_freedev(dev);
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}
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errout_with_pipe:
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pipe_free(pipeno);
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errout:
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set_errno(err);
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return ERROR;
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@ -172,10 +172,10 @@ FAR struct pipe_dev_s *pipecommon_allocdev(void)
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void pipecommon_freedev(FAR struct pipe_dev_s *dev)
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{
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sem_destroy(&dev->d_bfsem);
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sem_destroy(&dev->d_rdsem);
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sem_destroy(&dev->d_wrsem);
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kmm_free(dev);
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sem_destroy(&dev->d_bfsem);
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sem_destroy(&dev->d_rdsem);
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sem_destroy(&dev->d_wrsem);
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kmm_free(dev);
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}
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/****************************************************************************
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@ -203,9 +203,9 @@ int pipecommon_open(FAR struct file *filep)
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return -get_errno();
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}
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/* If this the first reference on the device, then allocate the buffer. In the
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* case of d_policy == 1, the buffer already be present when the pipe is
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* first opened.
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/* If this the first reference on the device, then allocate the buffer.
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* In the case of policy 1, the buffer already be present when the pipe
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* is first opened.
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*/
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if (dev->d_refs == 0 && dev->d_buffer == NULL)
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@ -303,7 +303,7 @@ int pipecommon_close(FAR struct file *filep)
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pipecommon_semtake(&dev->d_bfsem);
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/* Decrement the number of references on the pipe. Check if there are
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* still oustanding references to the pipe.
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* still outstanding references to the pipe.
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*/
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/* Check if the decremented reference count would go to zero */
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@ -331,12 +331,12 @@ int pipecommon_close(FAR struct file *filep)
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}
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/* What is the buffer management policy? Do we free the buffe when the
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* last client closes the pipe (d_policy == 0), or when the buffer becomes
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* empty (d_policy). In the latter case, the buffer data will remain
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* valid and can be obtained when the pipe is re-opened.
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* last client closes the pipe policy 0, or when the buffer becomes empty.
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* In the latter case, the buffer data will remain valid and can be
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* obtained when the pipe is re-opened.
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*/
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else if (dev->d_policy == 0 || dev->d_wrndx == dev->d_rdndx)
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else if (PIPE_IS_POLICY_0(dev->d_flags) || dev->d_wrndx == dev->d_rdndx)
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{
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/* Policy 0 or the buffer is empty ... deallocate the buffer now. */
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@ -349,6 +349,16 @@ int pipecommon_close(FAR struct file *filep)
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dev->d_rdndx = 0;
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dev->d_refs = 0;
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dev->d_nwriters = 0;
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/* If, in addition, we have been unlinked, then also need to free the
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* device structure as well to prevent a memory leak.
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*/
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if (PIPE_IS_UNLINKED(dev->d_flags))
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{
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pipecommon_freedev(dev);
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return OK;
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}
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}
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sem_post(&dev->d_bfsem);
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@ -678,10 +688,57 @@ int pipecommon_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
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if (cmd == PIPEIOC_POLICY)
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{
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dev->d_policy = (arg != 0);
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if (arg != 0)
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{
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PIPE_POLICY_1(dev->d_flags);
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}
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else
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{
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PIPE_POLICY_0(dev->d_flags);
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}
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return OK;
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}
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return -ENOTTY;
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}
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/****************************************************************************
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* Name: pipecommon_unlink
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****************************************************************************/
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int pipecommon_unlink(FAR void *priv)
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{
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/* The value passed to pipcommon_unlink is the private data pointer from
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* the inode that is being unlinked. If there are no open references to
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* the driver, then we must free up all resources used by the driver now.
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*/
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FAR struct pipe_dev_s *dev = (FAR struct pipe_dev_s *)priv;
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DEBUGASSERT(dev);
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/* Mark the pipe unlinked */
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PIPE_UNLINK(dev->d_flags);
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/* Are the any open references to the driver? */
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if (dev->d_refs == 0)
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{
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/* No.. free the buffer (if there is one) */
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if (dev->d_buffer)
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{
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kmm_free(dev->d_buffer);
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}
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/* And free the device structure. */
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pipecommon_freedev(dev);
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}
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return OK;
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}
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#endif /* CONFIG_DEV_PIPE_SIZE > 0 */
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@ -1,7 +1,7 @@
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/****************************************************************************
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* drivers/pipe/pipe_common.h
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*
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* Copyright (C) 2008-2009 Gregory Nutt. All rights reserved.
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* Copyright (C) 2008-2009, 2015 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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@ -67,6 +67,20 @@
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#define CONFIG_DEV_PIPE_MAXUSER 255
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/* d_flags values */
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#define PIPE_FLAG_POLICY (1 << 0) /* Bit 0: Policy=Free buffer when empty */
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#define PIPE_FLAG_UNLINKED (1 << 1) /* Bit 1: The driver has been unlinked */
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#define PIPE_POLICY_0(f) do { (f) &= ~PIPE_FLAG_POLICY; } while (0)
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#define PIPE_POLICY_1(f) do { (f) |= PIPE_FLAG_POLICY; } while (0)
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#define PIPE_IS_POLICY_0(f) (((f) & PIPE_FLAG_POLICY) == 0)
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#define PIPE_IS_POLICY_1(f) (((f) & PIPE_FLAG_POLICY) != 0)
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#define PIPE_UNLINK(f) do { (f) |= PIPE_FLAG_UNLINKED; } while (0)
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#define PIPE_IS_UNLINKED(f) (((f) & PIPE_FLAG_UNLINKED) != 0)
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/****************************************************************************
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* Public Types
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****************************************************************************/
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@ -96,7 +110,7 @@ struct pipe_dev_s
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uint8_t d_refs; /* References counts on pipe (limited to 255) */
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uint8_t d_nwriters; /* Number of reference counts for write access */
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uint8_t d_pipeno; /* Pipe minor number */
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bool d_policy; /* Buffer policy: 0=free on close; 1=free on empty */
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uint8_t d_flags; /* See PIPE_FLAG_* definitions */
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uint8_t *d_buffer; /* Buffer allocated when device opened */
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/* The following is a list if poll structures of threads waiting for
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@ -127,11 +141,11 @@ int pipecommon_close(FAR struct file *filep);
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ssize_t pipecommon_read(FAR struct file *, FAR char *, size_t);
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ssize_t pipecommon_write(FAR struct file *, FAR const char *, size_t);
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int pipecommon_ioctl(FAR struct file *filep, int cmd, unsigned long arg);
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#ifndef CONFIG_DISABLE_POLL
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int pipecommon_poll(FAR struct file *filep, FAR struct pollfd *fds,
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bool setup);
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#endif
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int pipecommon_unlink(FAR void *priv);
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#undef EXTERN
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#ifdef __cplusplus
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