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Reduce a fair bit of the atomics because we are now called with a

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lock from kern_conf.c and cdev's act a lot more like real objects
these days.
This commit is contained in:
Poul-Henning Kamp 2004-06-18 08:08:47 +00:00
parent e1ebf69098
commit 9d96090725
1 changed files with 55 additions and 73 deletions
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128
sys/fs/devfs/devfs_devs.c
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2000
* Copyright (c) 2000,2004
* Poul-Henning Kamp. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -58,7 +58,6 @@ static int devfs_noverflowwant = NDEVFSOVERFLOW;
static int devfs_noverflow;
static unsigned devfs_generation;
static void devfs_attemptoverflow(int insist);
static struct devfs_dirent *devfs_find (struct devfs_dirent *dd, const char *name, int namelen);
SYSCTL_NODE(_vfs, OID_AUTO, devfs, CTLFLAG_RW, 0, "DEVFS filesystem");
@ -137,43 +136,6 @@ devfs_itod (int inode)
return (NULL);
}
static void
devfs_attemptoverflow(int insist)
{
struct cdev ***ot;
int *or;
int n, nb;
/* Check if somebody beat us to it */
if (devfs_overflow != NULL)
return;
ot = NULL;
or = NULL;
n = devfs_noverflowwant;
nb = sizeof (struct cdev **) * n;
MALLOC(ot, struct cdev ***, nb, M_DEVFS, (insist ? M_WAITOK : M_NOWAIT) | M_ZERO);
if (ot == NULL)
goto bail;
nb = sizeof (int) * n;
MALLOC(or, int *, nb, M_DEVFS, (insist ? M_WAITOK : M_NOWAIT) | M_ZERO);
if (or == NULL)
goto bail;
if (!atomic_cmpset_ptr(&devfs_overflow, NULL, ot))
goto bail;
devfs_refoverflow = or;
devfs_noverflow = n;
printf("DEVFS Overflow table with %d entries allocated when %d in use\n", n, devfs_numino);
return;
bail:
/* Somebody beat us to it, or something went wrong. */
if (ot != NULL)
FREE(ot, M_DEVFS);
if (or != NULL)
FREE(or, M_DEVFS);
return;
}
static struct devfs_dirent *
devfs_find(struct devfs_dirent *dd, const char *name, int namelen)
{
@ -367,20 +329,26 @@ devfs_populate(struct devfs_mount *dm)
de->de_dir = dd;
devfs_rules_apply(dm, de);
TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
#if 0
printf("Add ino%d %s\n", i, dev->si_name);
#endif
}
}
lockmgr(&dm->dm_lock, LK_DOWNGRADE, 0, curthread);
return (0);
}
/*
* devfs_create() and devfs_destroy() are called from kern_conf.c and
* in both cases the devlock() mutex is held, so no further locking
* is necesary and no sleeping allowed.
*/
void
devfs_create(struct cdev *dev)
{
int ino, i, *ip;
struct cdev **dp;
struct cdev **ot;
int *or;
int n;
for (;;) {
/* Grab the next inode number */
@ -389,56 +357,70 @@ devfs_create(struct cdev *dev)
/* wrap around when we reach the end */
if (i >= NDEVFSINO + devfs_noverflow)
i = 3;
if (!atomic_cmpset_int(&devfs_nextino, ino, i))
continue;
devfs_nextino = i;
/* see if it was occupied */
dp = devfs_itod(ino);
if (dp == NULL)
Debugger("dp == NULL\n");
KASSERT(dp != NULL, ("DEVFS: No devptr inode %d", ino));
if (*dp != NULL)
continue;
ip = devfs_itor(ino);
if (ip == NULL)
Debugger("ip == NULL\n");
KASSERT(ip != NULL, ("DEVFS: No iptr inode %d", ino));
if (*ip != 0)
continue;
if (!atomic_cmpset_ptr(dp, NULL, dev))
continue;
dev->si_inode = ino;
for (;;) {
i = devfs_topino;
if (i >= ino)
break;
if (atomic_cmpset_int(&devfs_topino, i, ino))
break;
printf("failed topino %d %d\n", i, ino);
}
break;
}
atomic_add_int(&devfs_numino, 1);
atomic_add_int(&devfs_generation, 1);
if (devfs_overflow == NULL && devfs_numino + 100 > NDEVFSINO)
devfs_attemptoverflow(0);
*dp = dev;
dev->si_inode = ino;
if (i > devfs_topino)
devfs_topino = i;
devfs_numino++;
devfs_generation++;
if (devfs_overflow != NULL || devfs_numino + 100 < NDEVFSINO)
return;
/*
* Try to allocate overflow table
* XXX: we can probably be less panicy these days and a linked
* XXX: list of PAGESIZE/PTRSIZE entries might be a better idea.
*
* XXX: we may be into witness unlove here.
*/
n = devfs_noverflowwant;
ot = malloc(sizeof(*ot) * n, M_DEVFS, M_NOWAIT | M_ZERO);
if (ot == NULL)
return;
or = malloc(sizeof(*or) * n, M_DEVFS, M_NOWAIT | M_ZERO);
if (or == NULL) {
free(ot, M_DEVFS);
return;
}
devfs_overflow = ot;
devfs_refoverflow = or;
devfs_noverflow = n;
printf("DEVFS Overflow table with %d entries allocated\n", n);
return;
}
void
devfs_destroy(struct cdev *dev)
{
int ino, i;
int ino;
struct cdev **dp;
ino = dev->si_inode;
dev->si_inode = 0;
if (ino == 0)
return;
if (atomic_cmpset_ptr(devfs_itod(ino), dev, NULL)) {
atomic_add_int(&devfs_generation, 1);
atomic_add_int(&devfs_numino, -1);
i = devfs_nextino;
if (ino < i)
atomic_cmpset_int(&devfs_nextino, i, ino);
}
dp = devfs_itod(ino);
KASSERT(*dp == dev,
("DEVFS: destroying wrong cdev ino %d", ino));
*dp = NULL;
devfs_numino--;
devfs_generation++;
if (ino < devfs_nextino)
devfs_nextino = ino;
}