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1992/1029
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#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include "io.h"
/*
* The following routines
* scsibufreset, scsibuf, scsifree and scsialloc
* provide a pool of buffers used for scsi i/o.
* This is simplistic at best, and opportunities for
* deadlock abound.
*/
#define Nbuf 2
struct {
Lock;
Scsibuf *free;
} scsibufalloc;
void
scsibufreset(ulong datasize)
{
int i;
for(i = 0; i < Nbuf; i++)
scsifree(scsialloc(datasize));
lock(&scsibufalloc);
unlock(&scsibufalloc);
}
/*
* get a scsi io buffer of DATASIZE size
*/
Scsibuf *
scsibuf(void)
{
Scsibuf *b;
for(;;) {
lock(&scsibufalloc);
b = scsibufalloc.free;
if(b != 0) {
scsibufalloc.free = b->next;
unlock(&scsibufalloc);
return b;
}
unlock(&scsibufalloc);
resrcwait(0);
}
return 0; /* not reached */
}
void
scsifree(Scsibuf *b)
{
lock(&scsibufalloc);
b->next = scsibufalloc.free;
scsibufalloc.free = b;
unlock(&scsibufalloc);
}
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