Subject: [take31 6/10] kevent: Pipe notifications.

From: Evgeniy Polyakov <[email-masked]>
Date: Mon, 8 Jan 2007 22:25:59 +0300

Pipe notifications.

diff --git a/fs/pipe.c b/fs/pipe.c
index 68090e8..0c75bf1 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -16,6 +16,7 @@
 #include <linux/uio.h>
 #include <linux/highmem.h>
 #include <linux/pagemap.h>
+#include <linux/kevent.h>
 
 #include <asm/uaccess.h>
 #include <asm/ioctls.h>
@@ -313,6 +314,7 @@ redo:
 			break;
 		}
 		if (do_wakeup) {
+			kevent_pipe_notify(inode, KEVENT_SOCKET_SEND);
 			wake_up_interruptible_sync(&pipe->wait);
  			kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 		}
@@ -322,6 +324,7 @@ redo:
 
 	/* Signal writers asynchronously that there is more room. */
 	if (do_wakeup) {
+		kevent_pipe_notify(inode, KEVENT_SOCKET_SEND);
 		wake_up_interruptible(&pipe->wait);
 		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 	}
@@ -484,6 +487,7 @@ redo2:
 			break;
 		}
 		if (do_wakeup) {
+			kevent_pipe_notify(inode, KEVENT_SOCKET_RECV);
 			wake_up_interruptible_sync(&pipe->wait);
 			kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 			do_wakeup = 0;
@@ -495,6 +499,7 @@ redo2:
 out:
 	mutex_unlock(&inode->i_mutex);
 	if (do_wakeup) {
+		kevent_pipe_notify(inode, KEVENT_SOCKET_RECV);
 		wake_up_interruptible(&pipe->wait);
 		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 	}
@@ -590,6 +595,7 @@ pipe_release(struct inode *inode, int decr, int decw)
 		free_pipe_info(inode);
 	} else {
 		wake_up_interruptible(&pipe->wait);
+		kevent_pipe_notify(inode, KEVENT_SOCKET_SEND|KEVENT_SOCKET_RECV);
 		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 	}
diff --git a/kernel/kevent/kevent_pipe.c b/kernel/kevent/kevent_pipe.c
new file mode 100644
index 0000000..91dc1eb
--- /dev/null
+++ b/kernel/kevent/kevent_pipe.c
@@ -0,0 +1,123 @@
+/*
+ * 	kevent_pipe.c
+ * 
+ * 2006 Copyright (c) Evgeniy Polyakov <[email-masked]>
+ * All rights reserved.
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/kevent.h>
+#include <linux/pipe_fs_i.h>
+
+static int kevent_pipe_callback(struct kevent *k)
+{
+	struct inode *inode = k->st->origin;
+	struct pipe_inode_info *pipe = inode->i_pipe;
+	int nrbufs = pipe->nrbufs;
+
+	if (k->event.event & KEVENT_SOCKET_RECV && nrbufs > 0) {
+		if (!pipe->writers)
+			return -1;
+		return 1;
+	}
+	
+	if (k->event.event & KEVENT_SOCKET_SEND && nrbufs < PIPE_BUFFERS) {
+		if (!pipe->readers)
+			return -1;
+		return 1;
+	}
+
+	return 0;
+}
+
+int kevent_pipe_enqueue(struct kevent *k)
+{
+	struct file *pipe;
+	int err = -EBADF;
+	struct inode *inode;
+
+	pipe = fget(k->event.id.raw[0]);
+	if (!pipe)
+		goto err_out_exit;
+
+	inode = igrab(pipe->f_dentry->d_inode);
+	if (!inode)
+		goto err_out_fput;
+
+	err = -EINVAL;
+	if (!S_ISFIFO(inode->i_mode))
+		goto err_out_iput;
+
+	err = kevent_storage_enqueue(&inode->st, k);
+	if (err)
+		goto err_out_iput;
+
+	if (k->event.req_flags & KEVENT_REQ_ALWAYS_QUEUE) {
+		kevent_requeue(k);
+		err = 0;
+	} else {
+		err = k->callbacks.callback(k);
+		if (err)
+			goto err_out_dequeue;
+	}
+
+	fput(pipe);
+
+	return err;
+
+err_out_dequeue:
+	kevent_storage_dequeue(k->st, k);
+err_out_iput:
+	iput(inode);
+err_out_fput:
+	fput(pipe);
+err_out_exit:
+	return err;
+}
+
+int kevent_pipe_dequeue(struct kevent *k)
+{
+	struct inode *inode = k->st->origin;
+
+	kevent_storage_dequeue(k->st, k);
+	iput(inode);
+
+	return 0;
+}
+
+void kevent_pipe_notify(struct inode *inode, u32 event)
+{
+	kevent_storage_ready(&inode->st, NULL, event);
+}
+
+static int __init kevent_init_pipe(void)
+{
+	struct kevent_callbacks sc = {
+		.callback = &kevent_pipe_callback,
+		.enqueue = &kevent_pipe_enqueue,
+		.dequeue = &kevent_pipe_dequeue,
+		.flags = 0,
+	};
+
+	return kevent_add_callbacks(&sc, KEVENT_PIPE);
+}
+module_init(kevent_init_pipe);