zte's code,first commit
Change-Id: I9a04da59e459a9bc0d67f101f700d9d7dc8d681b
diff --git a/ap/os/linux/linux-3.4.x/fs/pipe.c b/ap/os/linux/linux-3.4.x/fs/pipe.c
new file mode 100644
index 0000000..abfb935
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/fs/pipe.c
@@ -0,0 +1,1333 @@
+/*
+ * linux/fs/pipe.c
+ *
+ * Copyright (C) 1991, 1992, 1999 Linus Torvalds
+ */
+
+#include <linux/mm.h>
+#include <linux/file.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/log2.h>
+#include <linux/mount.h>
+#include <linux/magic.h>
+#include <linux/pipe_fs_i.h>
+#include <linux/uio.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+#include <linux/audit.h>
+#include <linux/syscalls.h>
+#include <linux/fcntl.h>
+
+#include <asm/uaccess.h>
+#include <asm/ioctls.h>
+
+/*
+ * The max size that a non-root user is allowed to grow the pipe. Can
+ * be set by root in /proc/sys/fs/pipe-max-size
+ */
+unsigned int pipe_max_size = 1048576;
+
+/*
+ * Minimum pipe size, as required by POSIX
+ */
+unsigned int pipe_min_size = PAGE_SIZE;
+
+/*
+ * We use a start+len construction, which provides full use of the
+ * allocated memory.
+ * -- Florian Coosmann (FGC)
+ *
+ * Reads with count = 0 should always return 0.
+ * -- Julian Bradfield 1999-06-07.
+ *
+ * FIFOs and Pipes now generate SIGIO for both readers and writers.
+ * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
+ *
+ * pipe_read & write cleanup
+ * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
+ */
+
+static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
+{
+ if (pipe->inode)
+ mutex_lock_nested(&pipe->inode->i_mutex, subclass);
+}
+
+void pipe_lock(struct pipe_inode_info *pipe)
+{
+ /*
+ * pipe_lock() nests non-pipe inode locks (for writing to a file)
+ */
+ pipe_lock_nested(pipe, I_MUTEX_PARENT);
+}
+EXPORT_SYMBOL(pipe_lock);
+
+void pipe_unlock(struct pipe_inode_info *pipe)
+{
+ if (pipe->inode)
+ mutex_unlock(&pipe->inode->i_mutex);
+}
+EXPORT_SYMBOL(pipe_unlock);
+
+void pipe_double_lock(struct pipe_inode_info *pipe1,
+ struct pipe_inode_info *pipe2)
+{
+ BUG_ON(pipe1 == pipe2);
+
+ if (pipe1 < pipe2) {
+ pipe_lock_nested(pipe1, I_MUTEX_PARENT);
+ pipe_lock_nested(pipe2, I_MUTEX_CHILD);
+ } else {
+ pipe_lock_nested(pipe2, I_MUTEX_PARENT);
+ pipe_lock_nested(pipe1, I_MUTEX_CHILD);
+ }
+}
+
+/* Drop the inode semaphore and wait for a pipe event, atomically */
+void pipe_wait(struct pipe_inode_info *pipe)
+{
+ DEFINE_WAIT(wait);
+
+ /*
+ * Pipes are system-local resources, so sleeping on them
+ * is considered a noninteractive wait:
+ */
+ prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
+ pipe_unlock(pipe);
+ schedule();
+ finish_wait(&pipe->wait, &wait);
+ pipe_lock(pipe);
+}
+
+static int
+pipe_iov_copy_from_user(void *addr, int *offset, struct iovec *iov,
+ size_t *remaining, int atomic)
+{
+ unsigned long copy;
+
+ while (*remaining > 0) {
+ while (!iov->iov_len)
+ iov++;
+ copy = min_t(unsigned long, *remaining, iov->iov_len);
+
+ if (atomic) {
+ if (__copy_from_user_inatomic(addr + *offset,
+ iov->iov_base, copy))
+ return -EFAULT;
+ } else {
+ if (copy_from_user(addr + *offset,
+ iov->iov_base, copy))
+ return -EFAULT;
+ }
+ *offset += copy;
+ *remaining -= copy;
+ iov->iov_base += copy;
+ iov->iov_len -= copy;
+ }
+ return 0;
+}
+
+static int
+pipe_iov_copy_to_user(struct iovec *iov, void *addr, int *offset,
+ size_t *remaining, int atomic)
+{
+ unsigned long copy;
+
+ while (*remaining > 0) {
+ while (!iov->iov_len)
+ iov++;
+ copy = min_t(unsigned long, *remaining, iov->iov_len);
+
+ if (atomic) {
+ if (__copy_to_user_inatomic(iov->iov_base,
+ addr + *offset, copy))
+ return -EFAULT;
+ } else {
+ if (copy_to_user(iov->iov_base,
+ addr + *offset, copy))
+ return -EFAULT;
+ }
+ *offset += copy;
+ *remaining -= copy;
+ iov->iov_base += copy;
+ iov->iov_len -= copy;
+ }
+ return 0;
+}
+
+/*
+ * Attempt to pre-fault in the user memory, so we can use atomic copies.
+ * Returns the number of bytes not faulted in.
+ */
+static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len)
+{
+ while (!iov->iov_len)
+ iov++;
+
+ while (len > 0) {
+ unsigned long this_len;
+
+ this_len = min_t(unsigned long, len, iov->iov_len);
+ if (fault_in_pages_writeable(iov->iov_base, this_len))
+ break;
+
+ len -= this_len;
+ iov++;
+ }
+
+ return len;
+}
+
+/*
+ * Pre-fault in the user memory, so we can use atomic copies.
+ */
+static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len)
+{
+ while (!iov->iov_len)
+ iov++;
+
+ while (len > 0) {
+ unsigned long this_len;
+
+ this_len = min_t(unsigned long, len, iov->iov_len);
+ fault_in_pages_readable(iov->iov_base, this_len);
+ len -= this_len;
+ iov++;
+ }
+}
+
+static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
+{
+ struct page *page = buf->page;
+
+ /*
+ * If nobody else uses this page, and we don't already have a
+ * temporary page, let's keep track of it as a one-deep
+ * allocation cache. (Otherwise just release our reference to it)
+ */
+ if (page_count(page) == 1 && !pipe->tmp_page)
+ pipe->tmp_page = page;
+ else
+ page_cache_release(page);
+}
+
+/**
+ * generic_pipe_buf_map - virtually map a pipe buffer
+ * @pipe: the pipe that the buffer belongs to
+ * @buf: the buffer that should be mapped
+ * @atomic: whether to use an atomic map
+ *
+ * Description:
+ * This function returns a kernel virtual address mapping for the
+ * pipe_buffer passed in @buf. If @atomic is set, an atomic map is provided
+ * and the caller has to be careful not to fault before calling
+ * the unmap function.
+ *
+ * Note that this function occupies KM_USER0 if @atomic != 0.
+ */
+void *generic_pipe_buf_map(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf, int atomic)
+{
+ if (atomic) {
+ buf->flags |= PIPE_BUF_FLAG_ATOMIC;
+ return kmap_atomic(buf->page);
+ }
+
+ return kmap(buf->page);
+}
+EXPORT_SYMBOL(generic_pipe_buf_map);
+
+/**
+ * generic_pipe_buf_unmap - unmap a previously mapped pipe buffer
+ * @pipe: the pipe that the buffer belongs to
+ * @buf: the buffer that should be unmapped
+ * @map_data: the data that the mapping function returned
+ *
+ * Description:
+ * This function undoes the mapping that ->map() provided.
+ */
+void generic_pipe_buf_unmap(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf, void *map_data)
+{
+ if (buf->flags & PIPE_BUF_FLAG_ATOMIC) {
+ buf->flags &= ~PIPE_BUF_FLAG_ATOMIC;
+ kunmap_atomic(map_data);
+ } else
+ kunmap(buf->page);
+}
+EXPORT_SYMBOL(generic_pipe_buf_unmap);
+
+/**
+ * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer
+ * @pipe: the pipe that the buffer belongs to
+ * @buf: the buffer to attempt to steal
+ *
+ * Description:
+ * This function attempts to steal the &struct page attached to
+ * @buf. If successful, this function returns 0 and returns with
+ * the page locked. The caller may then reuse the page for whatever
+ * he wishes; the typical use is insertion into a different file
+ * page cache.
+ */
+int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
+{
+ struct page *page = buf->page;
+
+ /*
+ * A reference of one is golden, that means that the owner of this
+ * page is the only one holding a reference to it. lock the page
+ * and return OK.
+ */
+ if (page_count(page) == 1) {
+ lock_page(page);
+ return 0;
+ }
+
+ return 1;
+}
+EXPORT_SYMBOL(generic_pipe_buf_steal);
+
+/**
+ * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
+ * @pipe: the pipe that the buffer belongs to
+ * @buf: the buffer to get a reference to
+ *
+ * Description:
+ * This function grabs an extra reference to @buf. It's used in
+ * in the tee() system call, when we duplicate the buffers in one
+ * pipe into another.
+ */
+void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
+{
+ page_cache_get(buf->page);
+}
+EXPORT_SYMBOL(generic_pipe_buf_get);
+
+/**
+ * generic_pipe_buf_confirm - verify contents of the pipe buffer
+ * @info: the pipe that the buffer belongs to
+ * @buf: the buffer to confirm
+ *
+ * Description:
+ * This function does nothing, because the generic pipe code uses
+ * pages that are always good when inserted into the pipe.
+ */
+int generic_pipe_buf_confirm(struct pipe_inode_info *info,
+ struct pipe_buffer *buf)
+{
+ return 0;
+}
+EXPORT_SYMBOL(generic_pipe_buf_confirm);
+
+/**
+ * generic_pipe_buf_release - put a reference to a &struct pipe_buffer
+ * @pipe: the pipe that the buffer belongs to
+ * @buf: the buffer to put a reference to
+ *
+ * Description:
+ * This function releases a reference to @buf.
+ */
+void generic_pipe_buf_release(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
+{
+ page_cache_release(buf->page);
+}
+EXPORT_SYMBOL(generic_pipe_buf_release);
+
+static const struct pipe_buf_operations anon_pipe_buf_ops = {
+ .can_merge = 1,
+ .map = generic_pipe_buf_map,
+ .unmap = generic_pipe_buf_unmap,
+ .confirm = generic_pipe_buf_confirm,
+ .release = anon_pipe_buf_release,
+ .steal = generic_pipe_buf_steal,
+ .get = generic_pipe_buf_get,
+};
+
+static const struct pipe_buf_operations packet_pipe_buf_ops = {
+ .can_merge = 0,
+ .map = generic_pipe_buf_map,
+ .unmap = generic_pipe_buf_unmap,
+ .confirm = generic_pipe_buf_confirm,
+ .release = anon_pipe_buf_release,
+ .steal = generic_pipe_buf_steal,
+ .get = generic_pipe_buf_get,
+};
+
+static ssize_t
+pipe_read(struct kiocb *iocb, const struct iovec *_iov,
+ unsigned long nr_segs, loff_t pos)
+{
+ struct file *filp = iocb->ki_filp;
+ struct inode *inode = filp->f_path.dentry->d_inode;
+ struct pipe_inode_info *pipe;
+ int do_wakeup;
+ ssize_t ret;
+ struct iovec *iov = (struct iovec *)_iov;
+ size_t total_len;
+
+ total_len = iov_length(iov, nr_segs);
+ /* Null read succeeds. */
+ if (unlikely(total_len == 0))
+ return 0;
+
+ do_wakeup = 0;
+ ret = 0;
+ mutex_lock(&inode->i_mutex);
+ pipe = inode->i_pipe;
+ for (;;) {
+ int bufs = pipe->nrbufs;
+ if (bufs) {
+ int curbuf = pipe->curbuf;
+ struct pipe_buffer *buf = pipe->bufs + curbuf;
+ const struct pipe_buf_operations *ops = buf->ops;
+ void *addr;
+ size_t chars = buf->len, remaining;
+ int error, atomic;
+
+ if (chars > total_len)
+ chars = total_len;
+
+ error = ops->confirm(pipe, buf);
+ if (error) {
+ if (!ret)
+ ret = error;
+ break;
+ }
+
+ atomic = !iov_fault_in_pages_write(iov, chars);
+ remaining = chars;
+redo:
+ addr = ops->map(pipe, buf, atomic);
+ error = pipe_iov_copy_to_user(iov, addr, &buf->offset,
+ &remaining, atomic);
+ ops->unmap(pipe, buf, addr);
+ if (unlikely(error)) {
+ /*
+ * Just retry with the slow path if we failed.
+ */
+ if (atomic) {
+ atomic = 0;
+ goto redo;
+ }
+ if (!ret)
+ ret = error;
+ break;
+ }
+ ret += chars;
+ buf->len -= chars;
+
+ /* Was it a packet buffer? Clean up and exit */
+ if (buf->flags & PIPE_BUF_FLAG_PACKET) {
+ total_len = chars;
+ buf->len = 0;
+ }
+
+ if (!buf->len) {
+ buf->ops = NULL;
+ ops->release(pipe, buf);
+ curbuf = (curbuf + 1) & (pipe->buffers - 1);
+ pipe->curbuf = curbuf;
+ pipe->nrbufs = --bufs;
+ do_wakeup = 1;
+ }
+ total_len -= chars;
+ if (!total_len)
+ break; /* common path: read succeeded */
+ }
+ if (bufs) /* More to do? */
+ continue;
+ if (!pipe->writers)
+ break;
+ if (!pipe->waiting_writers) {
+ /* syscall merging: Usually we must not sleep
+ * if O_NONBLOCK is set, or if we got some data.
+ * But if a writer sleeps in kernel space, then
+ * we can wait for that data without violating POSIX.
+ */
+ if (ret)
+ break;
+ if (filp->f_flags & O_NONBLOCK) {
+ ret = -EAGAIN;
+ break;
+ }
+ }
+ if (signal_pending(current)) {
+ if (!ret)
+ ret = -ERESTARTSYS;
+ break;
+ }
+ if (do_wakeup) {
+ wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
+ kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
+ }
+ pipe_wait(pipe);
+ }
+ mutex_unlock(&inode->i_mutex);
+
+ /* Signal writers asynchronously that there is more room. */
+ if (do_wakeup) {
+ wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
+ kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
+ }
+ if (ret > 0)
+ file_accessed(filp);
+ return ret;
+}
+
+static inline int is_packetized(struct file *file)
+{
+ return (file->f_flags & O_DIRECT) != 0;
+}
+
+static ssize_t
+pipe_write(struct kiocb *iocb, const struct iovec *_iov,
+ unsigned long nr_segs, loff_t ppos)
+{
+ struct file *filp = iocb->ki_filp;
+ struct inode *inode = filp->f_path.dentry->d_inode;
+ struct pipe_inode_info *pipe;
+ ssize_t ret;
+ int do_wakeup;
+ struct iovec *iov = (struct iovec *)_iov;
+ size_t total_len;
+ ssize_t chars;
+
+ total_len = iov_length(iov, nr_segs);
+ /* Null write succeeds. */
+ if (unlikely(total_len == 0))
+ return 0;
+
+ do_wakeup = 0;
+ ret = 0;
+ mutex_lock(&inode->i_mutex);
+ pipe = inode->i_pipe;
+
+ if (!pipe->readers) {
+ send_sig(SIGPIPE, current, 0);
+ ret = -EPIPE;
+ goto out;
+ }
+
+ /* We try to merge small writes */
+ chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
+ if (pipe->nrbufs && chars != 0) {
+ int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
+ (pipe->buffers - 1);
+ struct pipe_buffer *buf = pipe->bufs + lastbuf;
+ const struct pipe_buf_operations *ops = buf->ops;
+ int offset = buf->offset + buf->len;
+
+ if (ops->can_merge && offset + chars <= PAGE_SIZE) {
+ int error, atomic = 1;
+ void *addr;
+ size_t remaining = chars;
+
+ error = ops->confirm(pipe, buf);
+ if (error)
+ goto out;
+
+ iov_fault_in_pages_read(iov, chars);
+redo1:
+ addr = ops->map(pipe, buf, atomic);
+ error = pipe_iov_copy_from_user(addr, &offset, iov,
+ &remaining, atomic);
+ ops->unmap(pipe, buf, addr);
+ ret = error;
+ do_wakeup = 1;
+ if (error) {
+ if (atomic) {
+ atomic = 0;
+ goto redo1;
+ }
+ goto out;
+ }
+ buf->len += chars;
+ total_len -= chars;
+ ret = chars;
+ if (!total_len)
+ goto out;
+ }
+ }
+
+ for (;;) {
+ int bufs;
+
+ if (!pipe->readers) {
+ send_sig(SIGPIPE, current, 0);
+ if (!ret)
+ ret = -EPIPE;
+ break;
+ }
+ bufs = pipe->nrbufs;
+ if (bufs < pipe->buffers) {
+ int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
+ struct pipe_buffer *buf = pipe->bufs + newbuf;
+ struct page *page = pipe->tmp_page;
+ char *src;
+ int error, atomic = 1;
+ int offset = 0;
+ size_t remaining;
+
+ if (!page) {
+ page = alloc_page(GFP_HIGHUSER);
+ if (unlikely(!page)) {
+ ret = ret ? : -ENOMEM;
+ break;
+ }
+ pipe->tmp_page = page;
+ }
+ /* Always wake up, even if the copy fails. Otherwise
+ * we lock up (O_NONBLOCK-)readers that sleep due to
+ * syscall merging.
+ * FIXME! Is this really true?
+ */
+ do_wakeup = 1;
+ chars = PAGE_SIZE;
+ if (chars > total_len)
+ chars = total_len;
+
+ iov_fault_in_pages_read(iov, chars);
+ remaining = chars;
+redo2:
+ if (atomic)
+ src = kmap_atomic(page);
+ else
+ src = kmap(page);
+
+ error = pipe_iov_copy_from_user(src, &offset, iov,
+ &remaining, atomic);
+ if (atomic)
+ kunmap_atomic(src);
+ else
+ kunmap(page);
+
+ if (unlikely(error)) {
+ if (atomic) {
+ atomic = 0;
+ goto redo2;
+ }
+ if (!ret)
+ ret = error;
+ break;
+ }
+ ret += chars;
+
+ /* Insert it into the buffer array */
+ buf->page = page;
+ buf->ops = &anon_pipe_buf_ops;
+ buf->offset = 0;
+ buf->len = chars;
+ buf->flags = 0;
+ if (is_packetized(filp)) {
+ buf->ops = &packet_pipe_buf_ops;
+ buf->flags = PIPE_BUF_FLAG_PACKET;
+ }
+ pipe->nrbufs = ++bufs;
+ pipe->tmp_page = NULL;
+
+ total_len -= chars;
+ if (!total_len)
+ break;
+ }
+ if (bufs < pipe->buffers)
+ continue;
+ if (filp->f_flags & O_NONBLOCK) {
+ if (!ret)
+ ret = -EAGAIN;
+ break;
+ }
+ if (signal_pending(current)) {
+ if (!ret)
+ ret = -ERESTARTSYS;
+ break;
+ }
+ if (do_wakeup) {
+ wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
+ kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
+ do_wakeup = 0;
+ }
+ pipe->waiting_writers++;
+ pipe_wait(pipe);
+ pipe->waiting_writers--;
+ }
+out:
+ mutex_unlock(&inode->i_mutex);
+ if (do_wakeup) {
+ wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
+ kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
+ }
+ if (ret > 0)
+ file_update_time(filp);
+ return ret;
+}
+
+static ssize_t
+bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
+{
+ return -EBADF;
+}
+
+static ssize_t
+bad_pipe_w(struct file *filp, const char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ return -EBADF;
+}
+
+static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+ struct inode *inode = filp->f_path.dentry->d_inode;
+ struct pipe_inode_info *pipe;
+ int count, buf, nrbufs;
+
+ switch (cmd) {
+ case FIONREAD:
+ mutex_lock(&inode->i_mutex);
+ pipe = inode->i_pipe;
+ count = 0;
+ buf = pipe->curbuf;
+ nrbufs = pipe->nrbufs;
+ while (--nrbufs >= 0) {
+ count += pipe->bufs[buf].len;
+ buf = (buf+1) & (pipe->buffers - 1);
+ }
+ mutex_unlock(&inode->i_mutex);
+
+ return put_user(count, (int __user *)arg);
+ default:
+ return -EINVAL;
+ }
+}
+
+/* No kernel lock held - fine */
+static unsigned int
+pipe_poll(struct file *filp, poll_table *wait)
+{
+ unsigned int mask;
+ struct inode *inode = filp->f_path.dentry->d_inode;
+ struct pipe_inode_info *pipe = inode->i_pipe;
+ int nrbufs;
+
+ poll_wait(filp, &pipe->wait, wait);
+
+ /* Reading only -- no need for acquiring the semaphore. */
+ nrbufs = pipe->nrbufs;
+ mask = 0;
+ if (filp->f_mode & FMODE_READ) {
+ mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
+ if (!pipe->writers && filp->f_version != pipe->w_counter)
+ mask |= POLLHUP;
+ }
+
+ if (filp->f_mode & FMODE_WRITE) {
+ mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0;
+ /*
+ * Most Unices do not set POLLERR for FIFOs but on Linux they
+ * behave exactly like pipes for poll().
+ */
+ if (!pipe->readers)
+ mask |= POLLERR;
+ }
+
+ return mask;
+}
+
+static int
+pipe_release(struct inode *inode, int decr, int decw)
+{
+ struct pipe_inode_info *pipe;
+
+ mutex_lock(&inode->i_mutex);
+ pipe = inode->i_pipe;
+ pipe->readers -= decr;
+ pipe->writers -= decw;
+
+ if (!pipe->readers && !pipe->writers) {
+ free_pipe_info(inode);
+ } else {
+ wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM | POLLERR | POLLHUP);
+ kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
+ kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
+ }
+ mutex_unlock(&inode->i_mutex);
+
+ return 0;
+}
+
+static int
+pipe_read_fasync(int fd, struct file *filp, int on)
+{
+ struct inode *inode = filp->f_path.dentry->d_inode;
+ int retval;
+
+ mutex_lock(&inode->i_mutex);
+ retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers);
+ mutex_unlock(&inode->i_mutex);
+
+ return retval;
+}
+
+
+static int
+pipe_write_fasync(int fd, struct file *filp, int on)
+{
+ struct inode *inode = filp->f_path.dentry->d_inode;
+ int retval;
+
+ mutex_lock(&inode->i_mutex);
+ retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers);
+ mutex_unlock(&inode->i_mutex);
+
+ return retval;
+}
+
+
+static int
+pipe_rdwr_fasync(int fd, struct file *filp, int on)
+{
+ struct inode *inode = filp->f_path.dentry->d_inode;
+ struct pipe_inode_info *pipe = inode->i_pipe;
+ int retval;
+
+ mutex_lock(&inode->i_mutex);
+ retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
+ if (retval >= 0) {
+ retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
+ if (retval < 0) /* this can happen only if on == T */
+ fasync_helper(-1, filp, 0, &pipe->fasync_readers);
+ }
+ mutex_unlock(&inode->i_mutex);
+ return retval;
+}
+
+
+static int
+pipe_read_release(struct inode *inode, struct file *filp)
+{
+ return pipe_release(inode, 1, 0);
+}
+
+static int
+pipe_write_release(struct inode *inode, struct file *filp)
+{
+ return pipe_release(inode, 0, 1);
+}
+
+static int
+pipe_rdwr_release(struct inode *inode, struct file *filp)
+{
+ int decr, decw;
+
+ decr = (filp->f_mode & FMODE_READ) != 0;
+ decw = (filp->f_mode & FMODE_WRITE) != 0;
+ return pipe_release(inode, decr, decw);
+}
+
+static int
+pipe_read_open(struct inode *inode, struct file *filp)
+{
+ int ret = -ENOENT;
+
+ mutex_lock(&inode->i_mutex);
+
+ if (inode->i_pipe) {
+ ret = 0;
+ inode->i_pipe->readers++;
+ }
+
+ mutex_unlock(&inode->i_mutex);
+
+ return ret;
+}
+
+static int
+pipe_write_open(struct inode *inode, struct file *filp)
+{
+ int ret = -ENOENT;
+
+ mutex_lock(&inode->i_mutex);
+
+ if (inode->i_pipe) {
+ ret = 0;
+ inode->i_pipe->writers++;
+ }
+
+ mutex_unlock(&inode->i_mutex);
+
+ return ret;
+}
+
+static int
+pipe_rdwr_open(struct inode *inode, struct file *filp)
+{
+ int ret = -ENOENT;
+
+ if (!(filp->f_mode & (FMODE_READ|FMODE_WRITE)))
+ return -EINVAL;
+
+ mutex_lock(&inode->i_mutex);
+
+ if (inode->i_pipe) {
+ ret = 0;
+ if (filp->f_mode & FMODE_READ)
+ inode->i_pipe->readers++;
+ if (filp->f_mode & FMODE_WRITE)
+ inode->i_pipe->writers++;
+ }
+
+ mutex_unlock(&inode->i_mutex);
+
+ return ret;
+}
+
+/*
+ * The file_operations structs are not static because they
+ * are also used in linux/fs/fifo.c to do operations on FIFOs.
+ *
+ * Pipes reuse fifos' file_operations structs.
+ */
+const struct file_operations read_pipefifo_fops = {
+ .llseek = no_llseek,
+ .read = do_sync_read,
+ .aio_read = pipe_read,
+ .write = bad_pipe_w,
+ .poll = pipe_poll,
+ .unlocked_ioctl = pipe_ioctl,
+ .open = pipe_read_open,
+ .release = pipe_read_release,
+ .fasync = pipe_read_fasync,
+};
+
+const struct file_operations write_pipefifo_fops = {
+ .llseek = no_llseek,
+ .read = bad_pipe_r,
+ .write = do_sync_write,
+ .aio_write = pipe_write,
+ .poll = pipe_poll,
+ .unlocked_ioctl = pipe_ioctl,
+ .open = pipe_write_open,
+ .release = pipe_write_release,
+ .fasync = pipe_write_fasync,
+};
+
+const struct file_operations rdwr_pipefifo_fops = {
+ .llseek = no_llseek,
+ .read = do_sync_read,
+ .aio_read = pipe_read,
+ .write = do_sync_write,
+ .aio_write = pipe_write,
+ .poll = pipe_poll,
+ .unlocked_ioctl = pipe_ioctl,
+ .open = pipe_rdwr_open,
+ .release = pipe_rdwr_release,
+ .fasync = pipe_rdwr_fasync,
+};
+
+struct pipe_inode_info * alloc_pipe_info(struct inode *inode)
+{
+ struct pipe_inode_info *pipe;
+
+ pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
+ if (pipe) {
+ pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL);
+ if (pipe->bufs) {
+ init_waitqueue_head(&pipe->wait);
+ pipe->r_counter = pipe->w_counter = 1;
+ pipe->inode = inode;
+ pipe->buffers = PIPE_DEF_BUFFERS;
+ return pipe;
+ }
+ kfree(pipe);
+ }
+
+ return NULL;
+}
+
+void __free_pipe_info(struct pipe_inode_info *pipe)
+{
+ int i;
+
+ for (i = 0; i < pipe->buffers; i++) {
+ struct pipe_buffer *buf = pipe->bufs + i;
+ if (buf->ops)
+ buf->ops->release(pipe, buf);
+ }
+ if (pipe->tmp_page)
+ __free_page(pipe->tmp_page);
+ kfree(pipe->bufs);
+ kfree(pipe);
+}
+
+void free_pipe_info(struct inode *inode)
+{
+ __free_pipe_info(inode->i_pipe);
+ inode->i_pipe = NULL;
+}
+
+static struct vfsmount *pipe_mnt __read_mostly;
+
+/*
+ * pipefs_dname() is called from d_path().
+ */
+static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen)
+{
+ return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]",
+ dentry->d_inode->i_ino);
+}
+
+static const struct dentry_operations pipefs_dentry_operations = {
+ .d_dname = pipefs_dname,
+};
+
+static struct inode * get_pipe_inode(void)
+{
+ struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb);
+ struct pipe_inode_info *pipe;
+
+ if (!inode)
+ goto fail_inode;
+
+ inode->i_ino = get_next_ino();
+
+ pipe = alloc_pipe_info(inode);
+ if (!pipe)
+ goto fail_iput;
+ inode->i_pipe = pipe;
+
+ pipe->readers = pipe->writers = 1;
+ inode->i_fop = &rdwr_pipefifo_fops;
+
+ /*
+ * Mark the inode dirty from the very beginning,
+ * that way it will never be moved to the dirty
+ * list because "mark_inode_dirty()" will think
+ * that it already _is_ on the dirty list.
+ */
+ inode->i_state = I_DIRTY;
+ inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
+ inode->i_uid = current_fsuid();
+ inode->i_gid = current_fsgid();
+ inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+
+ return inode;
+
+fail_iput:
+ iput(inode);
+
+fail_inode:
+ return NULL;
+}
+
+struct file *create_write_pipe(int flags)
+{
+ int err;
+ struct inode *inode;
+ struct file *f;
+ struct path path;
+ struct qstr name = { .name = "" };
+
+ err = -ENFILE;
+ inode = get_pipe_inode();
+ if (!inode)
+ goto err;
+
+ err = -ENOMEM;
+ path.dentry = d_alloc_pseudo(pipe_mnt->mnt_sb, &name);
+ if (!path.dentry)
+ goto err_inode;
+ path.mnt = mntget(pipe_mnt);
+
+ d_instantiate(path.dentry, inode);
+
+ err = -ENFILE;
+ f = alloc_file(&path, FMODE_WRITE, &write_pipefifo_fops);
+ if (!f)
+ goto err_dentry;
+ f->f_mapping = inode->i_mapping;
+
+ f->f_flags = O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT));
+ f->f_version = 0;
+
+ return f;
+
+ err_dentry:
+ free_pipe_info(inode);
+ path_put(&path);
+ return ERR_PTR(err);
+
+ err_inode:
+ free_pipe_info(inode);
+ iput(inode);
+ err:
+ return ERR_PTR(err);
+}
+
+void free_write_pipe(struct file *f)
+{
+ free_pipe_info(f->f_dentry->d_inode);
+ path_put(&f->f_path);
+ put_filp(f);
+}
+
+struct file *create_read_pipe(struct file *wrf, int flags)
+{
+ /* Grab pipe from the writer */
+ struct file *f = alloc_file(&wrf->f_path, FMODE_READ,
+ &read_pipefifo_fops);
+ if (!f)
+ return ERR_PTR(-ENFILE);
+
+ path_get(&wrf->f_path);
+ f->f_flags = O_RDONLY | (flags & O_NONBLOCK);
+
+ return f;
+}
+
+int do_pipe_flags(int *fd, int flags)
+{
+ struct file *fw, *fr;
+ int error;
+ int fdw, fdr;
+
+ if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT))
+ return -EINVAL;
+
+ fw = create_write_pipe(flags);
+ if (IS_ERR(fw))
+ return PTR_ERR(fw);
+ fr = create_read_pipe(fw, flags);
+ error = PTR_ERR(fr);
+ if (IS_ERR(fr))
+ goto err_write_pipe;
+
+ error = get_unused_fd_flags(flags);
+ if (error < 0)
+ goto err_read_pipe;
+ fdr = error;
+
+ error = get_unused_fd_flags(flags);
+ if (error < 0)
+ goto err_fdr;
+ fdw = error;
+
+ audit_fd_pair(fdr, fdw);
+ fd_install(fdr, fr);
+ fd_install(fdw, fw);
+ fd[0] = fdr;
+ fd[1] = fdw;
+
+ return 0;
+
+ err_fdr:
+ put_unused_fd(fdr);
+ err_read_pipe:
+ path_put(&fr->f_path);
+ put_filp(fr);
+ err_write_pipe:
+ free_write_pipe(fw);
+ return error;
+}
+
+/*
+ * sys_pipe() is the normal C calling standard for creating
+ * a pipe. It's not the way Unix traditionally does this, though.
+ */
+SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
+{
+ int fd[2];
+ int error;
+
+ error = do_pipe_flags(fd, flags);
+ if (!error) {
+ if (copy_to_user(fildes, fd, sizeof(fd))) {
+ sys_close(fd[0]);
+ sys_close(fd[1]);
+ error = -EFAULT;
+ }
+ }
+ return error;
+}
+
+SYSCALL_DEFINE1(pipe, int __user *, fildes)
+{
+ return sys_pipe2(fildes, 0);
+}
+
+/*
+ * Allocate a new array of pipe buffers and copy the info over. Returns the
+ * pipe size if successful, or return -ERROR on error.
+ */
+static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages)
+{
+ struct pipe_buffer *bufs;
+
+ /*
+ * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
+ * expect a lot of shrink+grow operations, just free and allocate
+ * again like we would do for growing. If the pipe currently
+ * contains more buffers than arg, then return busy.
+ */
+ if (nr_pages < pipe->nrbufs)
+ return -EBUSY;
+
+ bufs = kcalloc(nr_pages, sizeof(*bufs), GFP_KERNEL | __GFP_NOWARN);
+ if (unlikely(!bufs))
+ return -ENOMEM;
+
+ /*
+ * The pipe array wraps around, so just start the new one at zero
+ * and adjust the indexes.
+ */
+ if (pipe->nrbufs) {
+ unsigned int tail;
+ unsigned int head;
+
+ tail = pipe->curbuf + pipe->nrbufs;
+ if (tail < pipe->buffers)
+ tail = 0;
+ else
+ tail &= (pipe->buffers - 1);
+
+ head = pipe->nrbufs - tail;
+ if (head)
+ memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
+ if (tail)
+ memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
+ }
+
+ pipe->curbuf = 0;
+ kfree(pipe->bufs);
+ pipe->bufs = bufs;
+ pipe->buffers = nr_pages;
+ return nr_pages * PAGE_SIZE;
+}
+
+/*
+ * Currently we rely on the pipe array holding a power-of-2 number
+ * of pages.
+ */
+static inline unsigned int round_pipe_size(unsigned int size)
+{
+ unsigned long nr_pages;
+
+ nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ return roundup_pow_of_two(nr_pages) << PAGE_SHIFT;
+}
+
+/*
+ * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax
+ * will return an error.
+ */
+int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf,
+ size_t *lenp, loff_t *ppos)
+{
+ int ret;
+
+ ret = proc_dointvec_minmax(table, write, buf, lenp, ppos);
+ if (ret < 0 || !write)
+ return ret;
+
+ pipe_max_size = round_pipe_size(pipe_max_size);
+ return ret;
+}
+
+/*
+ * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
+ * location, so checking ->i_pipe is not enough to verify that this is a
+ * pipe.
+ */
+struct pipe_inode_info *get_pipe_info(struct file *file)
+{
+ struct inode *i = file->f_path.dentry->d_inode;
+
+ return S_ISFIFO(i->i_mode) ? i->i_pipe : NULL;
+}
+
+long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ struct pipe_inode_info *pipe;
+ long ret;
+
+ pipe = get_pipe_info(file);
+ if (!pipe)
+ return -EBADF;
+
+ mutex_lock(&pipe->inode->i_mutex);
+
+ switch (cmd) {
+ case F_SETPIPE_SZ: {
+ unsigned int size, nr_pages;
+
+ size = round_pipe_size(arg);
+ nr_pages = size >> PAGE_SHIFT;
+
+ ret = -EINVAL;
+ if (!nr_pages)
+ goto out;
+
+ if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
+ ret = -EPERM;
+ goto out;
+ }
+ ret = pipe_set_size(pipe, nr_pages);
+ break;
+ }
+ case F_GETPIPE_SZ:
+ ret = pipe->buffers * PAGE_SIZE;
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+out:
+ mutex_unlock(&pipe->inode->i_mutex);
+ return ret;
+}
+
+static const struct super_operations pipefs_ops = {
+ .destroy_inode = free_inode_nonrcu,
+ .statfs = simple_statfs,
+};
+
+/*
+ * pipefs should _never_ be mounted by userland - too much of security hassle,
+ * no real gain from having the whole whorehouse mounted. So we don't need
+ * any operations on the root directory. However, we need a non-trivial
+ * d_name - pipe: will go nicely and kill the special-casing in procfs.
+ */
+static struct dentry *pipefs_mount(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
+{
+ return mount_pseudo(fs_type, "pipe:", &pipefs_ops,
+ &pipefs_dentry_operations, PIPEFS_MAGIC);
+}
+
+static struct file_system_type pipe_fs_type = {
+ .name = "pipefs",
+ .mount = pipefs_mount,
+ .kill_sb = kill_anon_super,
+};
+
+static int __init init_pipe_fs(void)
+{
+ int err = register_filesystem(&pipe_fs_type);
+
+ if (!err) {
+ pipe_mnt = kern_mount(&pipe_fs_type);
+ if (IS_ERR(pipe_mnt)) {
+ err = PTR_ERR(pipe_mnt);
+ unregister_filesystem(&pipe_fs_type);
+ }
+ }
+ return err;
+}
+
+fs_initcall(init_pipe_fs);