ide: re-code ide_fixstring() loop to be less evil

On Friday 25 July 2008, Linus Torvalds wrote:
>
> On Fri, 25 Jul 2008, Ben Dooks wrote:
> >
> > personally, i would much prefer to see the loop being less evil
> > like:
> >
> > 	for (p = s; p < end; p += 2)
> > 		be16_to_cpus((u16 *)p);
>
> Well, in this case, the code actually depends on 'p' being back at the
> start of the buffer by the end of it all, so it would need some more
> changes than that.
>
> But yes, I applied David's patch, but I _also_ suspect that we would be
> better off without code that does horrid things like casts and assignments
> inside the function arguments.
>
> So it would be nice to re-code that loop to be more readable. But due to
> the reliance of 'p' being 's' after the loop, the minimal patch would be
> something like the appended.
>
> Bartlomiej - take this or not, I'm not going to commit it - I haven't
> tested it, nor do I even have any machines that would trigger it. So this
> is more a "maybe something like this" than anything else.

From: Linus Torvalds <torvalds@linux-foundation.org>
CC: Ben Dooks <ben-linux@fluff.org>
Cc: David Miller <davem@davemloft.net>
Cc: harvey.harrison@gmail.com
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

diff --git a/drivers/ide/ide-iops.c b/drivers/ide/ide-iops.c
index 8cfa6125c7a488df8a475b913a099fb652d5abd8..004803030f64d39eb834a1b451ca2fbe5002afa3 100644 (file)
--- a/drivers/ide/ide-iops.c
+++ b/drivers/ide/ide-iops.c
@@ -423,14 +423,16 @@ void ide_fix_driveid(u16 *id)
 
 void ide_fixstring (u8 *s, const int bytecount, const int byteswap)
 {
-       u8 *p = s, *end = &s[bytecount & ~1]; /* bytecount must be even */
+       u8 *p, *end = &s[bytecount & ~1]; /* bytecount must be even */
 
        if (byteswap) {
                /* convert from big-endian to host byte order */
-               for (p = end ; p != s;)
-                       be16_to_cpus((u16 *)(p -= 2));
+               for (p = s ; p != end ; p += 2)
+                       be16_to_cpus((u16 *) p);
        }
+
        /* strip leading blanks */
+       p = s;
        while (s != end && *s == ' ')
                ++s;
        /* compress internal blanks and strip trailing blanks */