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Commit 10fa1155 authored by Paolo 'Blaisorblade' Giarrusso's avatar Paolo 'Blaisorblade' Giarrusso Committed by Linus Torvalds
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[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: default avatarPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: default avatarJeff Dike <jdike@addtoit.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 05565b65

arch/um/sys-i386/delay.c

+0 −11
Original line number Original line Diff line number Diff line
@@ -27,14 +27,3 @@ void __udelay(unsigned long usecs) 
}

}





EXPORT_SYMBOL(__udelay);
 
EXPORT_SYMBOL(__udelay);
 


void __const_udelay(unsigned long usecs)

{

	int i, n;



	n = (loops_per_jiffy * HZ * usecs) / MILLION;

        for(i=0;i<n;i++)

                cpu_relax();

}



EXPORT_SYMBOL(__const_udelay);

arch/um/sys-x86_64/delay.c

+0 −11
Original line number Original line Diff line number Diff line
@@ -28,14 +28,3 @@ void __udelay(unsigned long usecs) 
}

}





EXPORT_SYMBOL(__udelay);
 
EXPORT_SYMBOL(__udelay);
 


void __const_udelay(unsigned long usecs)

{

	unsigned long i, n;



	n = (loops_per_jiffy * HZ * usecs) / MILLION;

        for(i=0;i<n;i++)

                cpu_relax();

}



EXPORT_SYMBOL(__const_udelay);

include/asm-um/delay.h

+14 −3
Original line number Original line Diff line number Diff line 
#ifndef __UM_DELAY_H

#ifndef __UM_DELAY_H

#define __UM_DELAY_H

#define __UM_DELAY_H





#include "asm/arch/delay.h"

#include "asm/archparam.h"



#define MILLION 1000000

#define MILLION 1000000





/* Undefined on purpose */

extern void __bad_udelay(void);



extern void __udelay(unsigned long usecs);

extern void __delay(unsigned long loops);



#define udelay(n) ((__builtin_constant_p(n) && (n) > 20000) ? \

	__bad_udelay() : __udelay(n))



/* It appears that ndelay is not used at all for UML, and has never been

 * implemented. */

extern void __unimplemented_ndelay(void);

#define ndelay(n) __unimplemented_ndelay()



#endif
 
#endif