RE: do_select() improvement ...

[Davide Libenzi <davidel@xmailserver.org>]

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On 21-Jun-2001 Davide Libenzi wrote:
>                         off = i / __NFDBITS;
> !                       if (!(i & (__NFDBITS - 1))) {
> !                               bits = BITS(fds, off);
> !                               if (!bits) {
> !                                       i += __NFDBITS;
> !                                       continue;
> !                               }


This is wrong.



>                         off = i / __NFDBITS;
> !                       if (!(i & (__NFDBITS - 1))) {
> !                               bits = BITS(fds, off);
> !                               if (!bits) {
> !                                       i += __NFDBITS - 1;
> !                                       continue;
> !                               }

This is right.





- Davide


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--- select.orig.c	Thu Jun 21 08:52:04 2001
+++ select.c	Thu Jun 21 12:09:25 2001
@@ -165,6 +165,7 @@
 	poll_table table, *wait;
 	int retval, i, off;
 	long __timeout = *timeout;
+	unsigned long bits;
 
  	read_lock(&current->files->file_lock);
 	retval = max_select_fd(n, fds);
@@ -187,7 +188,14 @@
 			struct file *file;
 
 			off = i / __NFDBITS;
-			if (!(bit & BITS(fds, off)))
+			if (!(i & (__NFDBITS - 1))) {
+				bits = BITS(fds, off);
+				if (!bits) {
+					i += __NFDBITS - 1;
+					continue;
+				}
+			}
+			if (!(bit & bits))
 				continue;
 			file = fget(i);
 			mask = POLLNVAL;