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linux-next/arch/um/sys-i386/delay.c
Paolo 'Blaisorblade' Giarrusso 10fa1155a2 [PATCH] uml: fix unreasonably long udelay
Currently we have a confused udelay implementation.

* __const_udelay does not accept usecs but xloops in i386 and x86_64
* our implementation requires usecs as arg
* it gets a xloops count when called by asm/arch/delay.h

Bugs related to this (extremely long shutdown times) where reported by some
x86_64 users, especially using Device Mapper.

To hit this bug, a compile-time constant time parameter must be passed -
that's why UML seems to work most times.  Fix this with a simple udelay
implementation.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-04-02 10:06:08 -07:00

30 lines
510 B
C

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <asm/param.h>
void __delay(unsigned long time)
{
/* Stolen from the i386 __loop_delay */
int d0;
__asm__ __volatile__(
"\tjmp 1f\n"
".align 16\n"
"1:\tjmp 2f\n"
".align 16\n"
"2:\tdecl %0\n\tjns 2b"
:"=&a" (d0)
:"0" (time));
}
void __udelay(unsigned long usecs)
{
int i, n;
n = (loops_per_jiffy * HZ * usecs) / MILLION;
for(i=0;i<n;i++)
cpu_relax();
}
EXPORT_SYMBOL(__udelay);