X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=fs%2Fpipe.c;h=e66ec48e95d8f44223ba960e5fe82a9c7acd962d;hb=d0ad3bc97c06fba5d37b4ca03c03b7eeeda39c47;hp=3a89592bdf577930b4c1698c4811261aa467cbf2;hpb=4750def52cb2c21732dda9aa1d43a07db37b0186;p=linux-2.6-omap-h63xx.git

diff --git a/fs/pipe.c b/fs/pipe.c
index 3a89592bdf5..e66ec48e95d 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -45,8 +45,7 @@ void pipe_wait(struct pipe_inode_info *pipe)
 	 * Pipes are system-local resources, so sleeping on them
 	 * is considered a noninteractive wait:
 	 */
-	prepare_to_wait(&pipe->wait, &wait,
-			TASK_INTERRUPTIBLE | TASK_NONINTERACTIVE);
+	prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
 	if (pipe->inode)
 		mutex_unlock(&pipe->inode->i_mutex);
 	schedule();
@@ -164,6 +163,20 @@ static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
 		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
+ *	passed in @pipe_buffer. 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)
 {
@@ -175,6 +188,15 @@ void *generic_pipe_buf_map(struct pipe_inode_info *pipe,
 	return kmap(buf->page);
 }
 
+/**
+ * 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)
 {
@@ -185,11 +207,28 @@ void generic_pipe_buf_unmap(struct pipe_inode_info *pipe,
 		kunmap(buf->page);
 }
 
+/**
+ * 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;
@@ -198,12 +237,32 @@ int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
 	return 1;
 }
 
-void generic_pipe_buf_get(struct pipe_inode_info *info, struct pipe_buffer *buf)
+/**
+ * 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);
 }
 
-int generic_pipe_buf_pin(struct pipe_inode_info *info, struct pipe_buffer *buf)
+/**
+ * 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;
 }
@@ -212,7 +271,7 @@ static const struct pipe_buf_operations anon_pipe_buf_ops = {
 	.can_merge = 1,
 	.map = generic_pipe_buf_map,
 	.unmap = generic_pipe_buf_unmap,
-	.pin = generic_pipe_buf_pin,
+	.confirm = generic_pipe_buf_confirm,
 	.release = anon_pipe_buf_release,
 	.steal = generic_pipe_buf_steal,
 	.get = generic_pipe_buf_get,
@@ -252,7 +311,7 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov,
 			if (chars > total_len)
 				chars = total_len;
 
-			error = ops->pin(pipe, buf);
+			error = ops->confirm(pipe, buf);
 			if (error) {
 				if (!ret)
 					error = ret;
@@ -323,7 +382,7 @@ redo:
 
 	/* Signal writers asynchronously that there is more room. */
 	if (do_wakeup) {
-		wake_up_interruptible(&pipe->wait);
+		wake_up_interruptible_sync(&pipe->wait);
 		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 	}
 	if (ret > 0)
@@ -373,7 +432,7 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov,
 			int error, atomic = 1;
 			void *addr;
 
-			error = ops->pin(pipe, buf);
+			error = ops->confirm(pipe, buf);
 			if (error)
 				goto out;
 
@@ -496,7 +555,7 @@ redo2:
 out:
 	mutex_unlock(&inode->i_mutex);
 	if (do_wakeup) {
-		wake_up_interruptible(&pipe->wait);
+		wake_up_interruptible_sync(&pipe->wait);
 		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 	}
 	if (ret > 0)
@@ -590,7 +649,7 @@ pipe_release(struct inode *inode, int decr, int decw)
 	if (!pipe->readers && !pipe->writers) {
 		free_pipe_info(inode);
 	} else {
-		wake_up_interruptible(&pipe->wait);
+		wake_up_interruptible_sync(&pipe->wait);
 		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 	}