[CFT] [PATCH] simplify simple_select

I've replaced simple_select in v4l1-compat.c: the current implementation
is just way to ugly to remain in the kernel.

Unfortunately I don't have a test setup.
Could someone test that the patch doesn't break the compatibility layer?
The patch is against 2.5.58.

Thanks,

--
   Manfred

--- 2.5/drivers/media/video/v4l1-compat.c	2003-01-15 20:30:20.000000000 +0100
+++ build-2.5/drivers/media/video/v4l1-compat.c	2003-01-16 23:50:26.000000000 +0100
@@ -199,66 +199,33 @@
 	return palette;
 }
 
-/*  Do an 'in' (wait for input) select on a single file descriptor  */
-/*  This stuff plaigarized from linux/fs/select.c     */
-#define __FD_IN(fds, n)	(fds->in + n)
-#define BIT(i)		(1UL << ((i)&(__NFDBITS-1)))
-#define SET(i,m)	(*(m) |= (i))
-extern int do_select(int n, fd_set_bits *fds, long *timeout);
-
-
 static int
 simple_select(struct file *file)
 {
-	fd_set_bits fds;
-	char *bits;
-	long timeout;
-	int i, fd, n, ret, size;
-
-	for (i = 0; i < current->files->max_fds; ++i)
-		if (file == current->files->fd[i])
-			break;
-	if (i == current->files->max_fds)
-		return -EINVAL;
-	fd = i;
-	n = fd + 1;
-
-	timeout = MAX_SCHEDULE_TIMEOUT;
-	/*
-	 * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
-	 * since we used fdset we need to allocate memory in units of
-	 * long-words. 
-	 */
-	ret = -ENOMEM;
-	size = FDS_BYTES(n);
-	bits = kmalloc(6 * size, GFP_KERNEL);
-	if (!bits)
-		goto out_nofds;
-	fds.in      = (unsigned long *)  bits;
-	fds.out     = (unsigned long *) (bits +   size);
-	fds.ex      = (unsigned long *) (bits + 2*size);
-	fds.res_in  = (unsigned long *) (bits + 3*size);
-	fds.res_out = (unsigned long *) (bits + 4*size);
-	fds.res_ex  = (unsigned long *) (bits + 5*size);
-
-	/*  All zero except our one file descriptor bit, for input  */
-	memset(bits, 0, 6 * size);
-	SET(BIT(fd), __FD_IN((&fds), fd / __NFDBITS));
-
-	ret = do_select(n, &fds, &timeout);
-
-	if (ret < 0)
-		goto out;
-	if (!ret) {
-		ret = -ERESTARTNOHAND;
-		if (signal_pending(current))
-			goto out;
-		ret = 0;
-	}
-out:
-	kfree(bits);
-out_nofds:
-	return ret;
+	int retval = 1;
+	struct poll_wqueues wait_table;
+	poll_table *table;
+
+	poll_initwait(&wait_table);
+	table = &wait_table.pt;
+	for (;;) {
+		int mask;
+		set_current_state(TASK_INTERRUPTIBLE);
+		mask = POLLIN;
+		if (file->f_op && file->f_op->poll)
+			mask = file->f_op->poll(file, table);
+		if (mask & POLLIN)
+			break;
+		table = NULL;
+		if (signal_pending(current)) {
+			retval = -ERESTARTSYS;
+			break;
+		}
+		schedule();
+	}
+	current->state = TASK_RUNNING;
+	poll_freewait(&wait_table);
+	return retval;
 }
 
 static int count_inputs(struct inode         *inode,