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MFC: Use an sx lock to serialize writes and remove D_NEEDGIANT.

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This commit is contained in:
jhb 2008-08-14 18:37:49 +00:00
parent 3376bddb2d
commit 0bf473dd8a
1 changed files with 14 additions and 3 deletions
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17
sys/dev/nvram/nvram.c
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@ -31,7 +31,9 @@
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/sx.h>
#include <sys/uio.h>
#include <sys/module.h>
@ -64,10 +66,10 @@ static d_read_t nvram_read;
static d_write_t nvram_write;
static struct cdev *nvram_dev;
static struct sx nvram_lock;
static struct cdevsw nvram_cdevsw = {
.d_version = D_VERSION,
.d_flags = D_NEEDGIANT,
.d_open = nvram_open,
.d_read = nvram_read,
.d_write = nvram_write,
@ -114,18 +116,24 @@ nvram_write(struct cdev *dev, struct uio *uio, int flags)
int i;
uint16_t sum;
sx_xlock(&nvram_lock);
/* Assert that we understand the existing checksum first! */
sum = rtcin(NVRAM_FIRST + CKSUM_MSB) << 8 |
rtcin(NVRAM_FIRST + CKSUM_LSB);
for (i = CKSUM_FIRST; i <= CKSUM_LAST; i++)
sum -= rtcin(NVRAM_FIRST + i);
if (sum != 0)
if (sum != 0) {
sx_xunlock(&nvram_lock);
return (EIO);
}
/* Bring in user data and write */
while (uio->uio_resid > 0 && error == 0) {
nv_off = uio->uio_offset + NVRAM_FIRST;
if (nv_off < NVRAM_FIRST || nv_off >= NVRAM_LAST)
if (nv_off < NVRAM_FIRST || nv_off >= NVRAM_LAST) {
sx_xunlock(&nvram_lock);
return (0); /* Signal EOF */
}
/* Single byte at a time */
error = uiomove(&v, 1, uio);
writertc(nv_off, v);
@ -136,6 +144,7 @@ nvram_write(struct cdev *dev, struct uio *uio, int flags)
sum += rtcin(NVRAM_FIRST + i);
writertc(NVRAM_FIRST + CKSUM_MSB, sum >> 8);
writertc(NVRAM_FIRST + CKSUM_LSB, sum);
sx_xunlock(&nvram_lock);
return (error);
}
@ -144,12 +153,14 @@ nvram_modevent(module_t mod __unused, int type, void *data __unused)
{
switch (type) {
case MOD_LOAD:
sx_init(&nvram_lock, "nvram");
nvram_dev = make_dev(&nvram_cdevsw, 0,
UID_ROOT, GID_KMEM, 0640, "nvram");
break;
case MOD_UNLOAD:
case MOD_SHUTDOWN:
destroy_dev(nvram_dev);
sx_destroy(&nvram_lock);
break;
default:
return (EOPNOTSUPP);