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Optimize the case of writing to /dev/zero, and clean up the

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surrounding code a bit.  Partly suggested by gwr.
This commit is contained in:
mycroft 1997-03-24 21:16:59 +00:00
parent f17ca2c65c
commit 46f55019b7
1 changed files with 8 additions and 14 deletions
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22
sys/arch/i386/i386/mem.c
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@ -1,4 +1,4 @@
/* $NetBSD: mem.c,v 1.31 1996/05/03 19:42:19 christos Exp $ */
/* $NetBSD: mem.c,v 1.32 1997/03/24 21:16:59 mycroft Exp $ */
/*
* Copyright (c) 1988 University of Utah.
@ -121,7 +121,7 @@ mmrw(dev, uio, flags)
}
physlock = 1;
}
while (uio->uio_resid > 0 && error == 0) {
while (uio->uio_resid > 0 && !error) {
iov = uio->uio_iov;
if (iov->iov_len == 0) {
uio->uio_iov++;
@ -143,7 +143,7 @@ mmrw(dev, uio, flags)
error = uiomove((caddr_t)vmmap + o, c, uio);
pmap_remove(pmap_kernel(), (vm_offset_t)vmmap,
(vm_offset_t)vmmap + NBPG);
continue;
break;
/* minor device 1 is kernel memory */
case 1:
@ -153,9 +153,9 @@ mmrw(dev, uio, flags)
uio->uio_rw == UIO_READ ? B_READ : B_WRITE))
return (EFAULT);
error = uiomove((caddr_t)v, c, uio);
continue;
break;
/* minor device 2 is EOF/RATHOLE */
/* minor device 2 is EOF/rathole */
case 2:
if (uio->uio_rw == UIO_WRITE)
uio->uio_resid = 0;
@ -164,8 +164,8 @@ mmrw(dev, uio, flags)
/* minor device 12 (/dev/zero) is source of nulls on read, rathole on write */
case 12:
if (uio->uio_rw == UIO_WRITE) {
c = iov->iov_len;
break;
uio->uio_resid = 0;
return (0);
}
if (zeropage == NULL) {
zeropage = (caddr_t)
@ -174,17 +174,11 @@ mmrw(dev, uio, flags)
}
c = min(iov->iov_len, CLBYTES);
error = uiomove(zeropage, c, uio);
continue;
break;
default:
return (ENXIO);
}
if (error)
break;
iov->iov_base += c;
iov->iov_len -= c;
uio->uio_offset += c;
uio->uio_resid -= c;
}
if (minor(dev) == 0) {
if (physlock > 1)