On Fri, Feb 18, 2005 at 04:33:03PM -0700, Jonathan Corbet wrote:
> [Since this is something I once looked at too...]
>
> > struct kobj_map *kobj_map_init(kobj_probe_t *base_probe,
> > - struct subsystem *s)
> > + struct subsystem *s, struct semaphore *sem)
>
> The only reason kobj_map_init() needed the subsystem argument was for
> the semaphore. Since you're passing that separately now, I would think
> that the subsystem argument could simply go away altogether.
>
> Once that's done, you should be able to delete cdev_subsys as well; when
> I cleaned that stuff up, I only left it there for kobj_map().
Doh, you're right, thanks for pointing this out. I missed that huge
comment you put in the code right where I modified it that said exactly
that...
So, here's a revised patch that I've added to my bk-driver tree.
thanks,
greg k-h
-------------
Subject: kmap: remove usage of rwsem from kobj_map.
This forces the caller to provide the lock, but as they all already had one,
it's not a big change.
It also removes the now-unneeded cdev_subsys. Thanks to Jon Corbet for
reminding me about that.
Signed-off-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>
diff -Nru a/drivers/base/map.c b/drivers/base/map.c
--- a/drivers/base/map.c 2005-02-22 10:44:13 -08:00
+++ b/drivers/base/map.c 2005-02-22 10:44:13 -08:00
@@ -25,7 +25,7 @@
int (*lock)(dev_t, void *);
void *data;
} *probes[255];
- struct rw_semaphore *sem;
+ struct semaphore *sem;
};
int kobj_map(struct kobj_map *domain, dev_t dev, unsigned long range,
@@ -53,7 +53,7 @@
p->range = range;
p->data = data;
}
- down_write(domain->sem);
+ down(domain->sem);
for (i = 0, p -= n; i < n; i++, p++, index++) {
struct probe **s = &domain->probes[index % 255];
while (*s && (*s)->range < range)
@@ -61,7 +61,7 @@
p->next = *s;
*s = p;
}
- up_write(domain->sem);
+ up(domain->sem);
return 0;
}
@@ -75,7 +75,7 @@
if (n > 255)
n = 255;
- down_write(domain->sem);
+ down(domain->sem);
for (i = 0; i < n; i++, index++) {
struct probe **s;
for (s = &domain->probes[index % 255]; *s; s = &(*s)->next) {
@@ -88,7 +88,7 @@
}
}
}
- up_write(domain->sem);
+ up(domain->sem);
kfree(found);
}
@@ -99,7 +99,7 @@
unsigned long best = ~0UL;
retry:
- down_read(domain->sem);
+ down(domain->sem);
for (p = domain->probes[MAJOR(dev) % 255]; p; p = p->next) {
struct kobject *(*probe)(dev_t, int *, void *);
struct module *owner;
@@ -120,7 +120,7 @@
module_put(owner);
continue;
}
- up_read(domain->sem);
+ up(domain->sem);
kobj = probe(dev, index, data);
/* Currently ->owner protects _only_ ->probe() itself. */
module_put(owner);
@@ -128,12 +128,11 @@
return kobj;
goto retry;
}
- up_read(domain->sem);
+ up(domain->sem);
return NULL;
}
-struct kobj_map *kobj_map_init(kobj_probe_t *base_probe,
- struct subsystem *s)
+struct kobj_map *kobj_map_init(kobj_probe_t *base_probe, struct semaphore *sem)
{
struct kobj_map *p = kmalloc(sizeof(struct kobj_map), GFP_KERNEL);
struct probe *base = kmalloc(sizeof(struct probe), GFP_KERNEL);
@@ -151,6 +150,6 @@
base->get = base_probe;
for (i = 0; i < 255; i++)
p->probes[i] = base;
- p->sem = &s->rwsem;
+ p->sem = sem;
return p;
}
diff -Nru a/drivers/block/genhd.c b/drivers/block/genhd.c
--- a/drivers/block/genhd.c 2005-02-22 10:44:13 -08:00
+++ b/drivers/block/genhd.c 2005-02-22 10:44:13 -08:00
@@ -302,7 +302,7 @@
static int __init genhd_device_init(void)
{
- bdev_map = kobj_map_init(base_probe, &block_subsys);
+ bdev_map = kobj_map_init(base_probe, &block_subsys_sem);
blk_dev_init();
subsystem_register(&block_subsys);
return 0;
diff -Nru a/fs/char_dev.c b/fs/char_dev.c
--- a/fs/char_dev.c 2005-02-22 10:44:13 -08:00
+++ b/fs/char_dev.c 2005-02-22 10:44:13 -08:00
@@ -28,7 +28,7 @@
#define MAX_PROBE_HASH 255 /* random */
-static DEFINE_RWLOCK(chrdevs_lock);
+static DECLARE_MUTEX(chrdevs_lock);
static struct char_device_struct {
struct char_device_struct *next;
@@ -54,13 +54,13 @@
len = sprintf(page, "Character devices:\n");
- read_lock(&chrdevs_lock);
+ down(&chrdevs_lock);
for (i = 0; i < ARRAY_SIZE(chrdevs) ; i++) {
for (cd = chrdevs[i]; cd; cd = cd->next)
len += sprintf(page+len, "%3d %s\n",
cd->major, cd->name);
}
- read_unlock(&chrdevs_lock);
+ up(&chrdevs_lock);
return len;
}
@@ -90,7 +90,7 @@
memset(cd, 0, sizeof(struct char_device_struct));
- write_lock_irq(&chrdevs_lock);
+ down(&chrdevs_lock);
/* temporary */
if (major == 0) {
@@ -125,10 +125,10 @@
}
cd->next = *cp;
*cp = cd;
- write_unlock_irq(&chrdevs_lock);
+ up(&chrdevs_lock);
return cd;
out:
- write_unlock_irq(&chrdevs_lock);
+ up(&chrdevs_lock);
kfree(cd);
return ERR_PTR(ret);
}
@@ -139,7 +139,7 @@
struct char_device_struct *cd = NULL, **cp;
int i = major_to_index(major);
- write_lock_irq(&chrdevs_lock);
+ up(&chrdevs_lock);
for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
if ((*cp)->major == major &&
(*cp)->baseminor == baseminor &&
@@ -149,7 +149,7 @@
cd = *cp;
*cp = cd->next;
}
- write_unlock_irq(&chrdevs_lock);
+ up(&chrdevs_lock);
return cd;
}
@@ -380,8 +380,6 @@
}
-static decl_subsys(cdev, NULL, NULL);
-
static void cdev_default_release(struct kobject *kobj)
{
struct cdev *p = container_of(kobj, struct cdev, kobj);
@@ -434,13 +432,7 @@
void __init chrdev_init(void)
{
-/*
- * Keep cdev_subsys around because (and only because) the kobj_map code
- * depends on the rwsem it contains. We don't make it public in sysfs,
- * however.
- */
- subsystem_init(&cdev_subsys);
- cdev_map = kobj_map_init(base_probe, &cdev_subsys);
+ cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
}
diff -Nru a/include/linux/kobj_map.h b/include/linux/kobj_map.h
--- a/include/linux/kobj_map.h 2005-02-22 10:44:13 -08:00
+++ b/include/linux/kobj_map.h 2005-02-22 10:44:13 -08:00
@@ -7,6 +7,6 @@
kobj_probe_t *, int (*)(dev_t, void *), void *);
void kobj_unmap(struct kobj_map *, dev_t, unsigned long);
struct kobject *kobj_lookup(struct kobj_map *, dev_t, int *);
-struct kobj_map *kobj_map_init(kobj_probe_t *, struct subsystem *);
+struct kobj_map *kobj_map_init(kobj_probe_t *, struct semaphore *);
#endif
-
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