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Simplify loops by putting interrupt test at end.

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This commit is contained in:
riastradh 2020-05-08 15:57:24 +00:00
parent 1b74d9d4a1
commit 7460c1de67
1 changed files with 22 additions and 44 deletions
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66
sys/dev/random.c
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@ -1,4 +1,4 @@
/* $NetBSD: random.c,v 1.5 2020/05/08 15:55:05 riastradh Exp $ */
/* $NetBSD: random.c,v 1.6 2020/05/08 15:57:24 riastradh Exp $ */
/*-
* Copyright (c) 2019 The NetBSD Foundation, Inc.
@ -47,7 +47,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: random.c,v 1.5 2020/05/08 15:55:05 riastradh Exp $");
__KERNEL_RCSID(0, "$NetBSD: random.c,v 1.6 2020/05/08 15:57:24 riastradh Exp $");
#include <sys/param.h>
#include <sys/types.h>
@ -213,7 +213,6 @@ random_read(dev_t dev, struct uio *uio, int flags)
struct nist_hash_drbg drbg;
uint8_t *buf;
int extractflags;
bool interruptible;
int error;
/* Get a buffer for transfers. */
@ -258,18 +257,10 @@ random_read(dev_t dev, struct uio *uio, int flags)
/* Promptly zero the seed. */
explicit_memset(seed, 0, sizeof seed);
/*
* Generate data. Assume no error until failure. No
* interruption at this point until we've generated at least
* one block of output.
*/
/* Generate data. */
error = 0;
interruptible = false;
while (uio->uio_resid) {
size_t n = uio->uio_resid;
/* No more than one buffer's worth. */
n = MIN(n, RANDOM_BUFSIZE);
size_t n = MIN(uio->uio_resid, RANDOM_BUFSIZE);
/*
* Clamp /dev/random output to the entropy capacity and
@ -286,22 +277,6 @@ random_read(dev_t dev, struct uio *uio, int flags)
CTASSERT(sizeof seed <= RANDOM_BUFSIZE);
}
/* Yield if requested. */
if (curcpu()->ci_schedstate.spc_flags & SPCF_SHOULDYIELD)
preempt();
/*
* Allow interruption, but only after providing a
* minimum number of bytes.
*/
CTASSERT(RANDOM_BUFSIZE >= 256);
/* Check for interruption. */
if (__predict_false(curlwp->l_flag & LW_PENDSIG) &&
interruptible && sigispending(curlwp, 0)) {
error = EINTR; /* XXX ERESTART? */
break;
}
/*
* Try to generate a block of data, but if we've hit
* the DRBG reseed interval, reseed.
@ -348,11 +323,17 @@ random_read(dev_t dev, struct uio *uio, int flags)
break;
}
/*
* We have generated one block of output, so it is
* reasonable to allow interruption after this point.
*/
interruptible = true;
/* Yield if requested. */
if (curcpu()->ci_schedstate.spc_flags & SPCF_SHOULDYIELD)
preempt();
/* Check for interruption after at least 256 bytes. */
CTASSERT(RANDOM_BUFSIZE >= 256);
if (__predict_false(curlwp->l_flag & LW_PENDSIG) &&
sigispending(curlwp, 0)) {
error = EINTR;
break;
}
}
out: /* Zero the buffer and free it. */
@ -401,10 +382,14 @@ random_write(dev_t dev, struct uio *uio, int flags)
/* Consume data. */
while (uio->uio_resid) {
size_t n = uio->uio_resid;
size_t n = MIN(uio->uio_resid, RANDOM_BUFSIZE);
/* No more than one buffer's worth in one step. */
n = MIN(uio->uio_resid, RANDOM_BUFSIZE);
/* Transfer n bytes in and enter them into the pool. */
error = uiomove(buf, n, uio);
if (error)
break;
rnd_add_data(&user_rndsource, buf, n, privileged ? n*NBBY : 0);
any = true;
/* Yield if requested. */
if (curcpu()->ci_schedstate.spc_flags & SPCF_SHOULDYIELD)
@ -416,13 +401,6 @@ random_write(dev_t dev, struct uio *uio, int flags)
error = EINTR; /* XXX ERESTART? */
break;
}
/* Transfer n bytes in and enter them into the pool. */
error = uiomove(buf, n, uio);
if (error)
break;
rnd_add_data(&user_rndsource, buf, n, privileged ? n*NBBY : 0);
any = true;
}
/* Zero the buffer and free it. */