linux-kernel - Re: no-op delay loops

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Message-ID: <20151201012546.GC23993@linux-mips.org>
Date:	Tue, 1 Dec 2015 02:25:46 +0100
From:	Ralf Baechle <ralf@...ux-mips.org>
To:	Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:	Arnd Bergmann <arnd@...db.de>, linux-mips@...ux-mips.org,
	linux-kernel@...r.kernel.org, Richard Henderson <rth@...ddle.net>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: no-op delay loops

On Mon, Nov 30, 2015 at 10:29:26PM +0100, Rasmus Villemoes wrote:

> OK, thanks. That's a very very long time ago.
> 
> FWIW, the remaining instances that my trivial coccinelle script found
> are

After your initial report I also wrote a coccinelle which is looking
also for delay loops implemented in while loops.  It found the following
two:

diff -u -p ./drivers/video/uvesafb.c /tmp/nothing/drivers/video/uvesafb.c
--- ./drivers/video/uvesafb.c
+++ /tmp/nothing/drivers/video/uvesafb.c
@@ -1142,7 +1142,6 @@ static int uvesafb_blank(int blank, stru
 		vga_wseq(NULL, 0x00, seq);
 
 		crtc17 |= vga_rcrt(NULL, 0x17) & ~0x80;
-		while (loop--);
 		vga_wcrt(NULL, 0x17, crtc17);
 		vga_wseq(NULL, 0x00, 0x03);
 	} else
diff -u -p ./arch/mips/pmc-sierra/yosemite/atmel_read_eeprom.c /tmp/nothing/arch/mips/pmc-sierra/yosemite/atmel_read_eeprom.c
--- ./arch/mips/pmc-sierra/yosemite/atmel_read_eeprom.c
+++ /tmp/nothing/arch/mips/pmc-sierra/yosemite/atmel_read_eeprom.c
@@ -37,7 +37,6 @@
 
 static void delay(int delay)
 {
-	while (delay--);
 }
 
 static void send_bit(unsigned char bit)

The 2nd file falls into my domain so I'm going to fix it.  Not sure
how the uvesafb one should be treated.

  Ralf
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