#include <linux/kmod.h>
#include <linux/init.h>
#include <linux/list.h>
+#include <linux/idr.h>
#include <linux/netdevice.h>
#include <linux/poll.h>
#include <linux/ppp_defs.h>
* channel.downl.
*/
-/*
- * A cardmap represents a mapping from unsigned integers to pointers,
- * and provides a fast "find lowest unused number" operation.
- * It uses a broad (32-way) tree with a bitmap at each level.
- * It is designed to be space-efficient for small numbers of entries
- * and time-efficient for large numbers of entries.
- */
-#define CARDMAP_ORDER 5
-#define CARDMAP_WIDTH (1U << CARDMAP_ORDER)
-#define CARDMAP_MASK (CARDMAP_WIDTH - 1)
-
-struct cardmap {
- int shift;
- unsigned long inuse;
- struct cardmap *parent;
- void *ptr[CARDMAP_WIDTH];
-};
-static void *cardmap_get(struct cardmap *map, unsigned int nr);
-static int cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
-static unsigned int cardmap_find_first_free(struct cardmap *map);
-static void cardmap_destroy(struct cardmap **map);
-
/*
* all_ppp_mutex protects the all_ppp_units mapping.
* It also ensures that finding a ppp unit in the all_ppp_units map
* and updating its file.refcnt field is atomic.
*/
static DEFINE_MUTEX(all_ppp_mutex);
-static struct cardmap *all_ppp_units;
static atomic_t ppp_unit_count = ATOMIC_INIT(0);
+static struct idr ppp_units_idr;
/*
* all_channels_lock protects all_channels and last_channel_index,
static int ppp_connect_channel(struct channel *pch, int unit);
static int ppp_disconnect_channel(struct channel *pch);
static void ppp_destroy_channel(struct channel *pch);
+static int unit_get(struct idr *p, void *ptr);
+static void unit_put(struct idr *p, int n);
+static void *unit_find(struct idr *p, int n);
static struct class *ppp_class;
"ppp");
}
+ idr_init(&ppp_units_idr);
+
out:
if (err)
printk(KERN_ERR "failed to register PPP device (%d)\n", err);
ret = -EEXIST;
mutex_lock(&all_ppp_mutex);
- if (unit < 0)
- unit = cardmap_find_first_free(all_ppp_units);
- else if (cardmap_get(all_ppp_units, unit) != NULL)
- goto out2; /* unit already exists */
+
+ if (unit < 0) {
+ unit = unit_get(&ppp_units_idr, ppp);
+ if (unit < 0) {
+ *retp = unit;
+ goto out2;
+ }
+ } else {
+ if (unit_find(&ppp_units_idr, unit))
+ goto out2; /* unit already exists */
+ else {
+ /* darn, someone is cheatting us? */
+ *retp = -EINVAL;
+ goto out2;
+ }
+ }
/* Initialize the new ppp unit */
ppp->file.index = unit;
ret = register_netdev(dev);
if (ret != 0) {
+ unit_put(&ppp_units_idr, unit);
printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
dev->name, ret);
goto out2;
}
atomic_inc(&ppp_unit_count);
- ret = cardmap_set(&all_ppp_units, unit, ppp);
- if (ret != 0)
- goto out3;
-
mutex_unlock(&all_ppp_mutex);
+
*retp = 0;
return ppp;
-out3:
- atomic_dec(&ppp_unit_count);
- unregister_netdev(dev);
out2:
mutex_unlock(&all_ppp_mutex);
free_netdev(dev);
unregister_netdev(dev);
free_netdev(dev);
}
- cardmap_set(&all_ppp_units, ppp->file.index, NULL);
+ unit_put(&ppp_units_idr, ppp->file.index);
ppp->file.dead = 1;
ppp->owner = NULL;
wake_up_interruptible(&ppp->file.rwait);
static struct ppp *
ppp_find_unit(int unit)
{
- return cardmap_get(all_ppp_units, unit);
+ return unit_find(&ppp_units_idr, unit);
}
/*
/* should never happen */
if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
printk(KERN_ERR "PPP: removing module but units remain!\n");
- cardmap_destroy(&all_ppp_units);
unregister_chrdev(PPP_MAJOR, "ppp");
device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
class_destroy(ppp_class);
+ idr_destroy(&ppp_units_idr);
}
/*
- * Cardmap implementation.
+ * Units handling. Caller must protect concurrent access
+ * by holding all_ppp_mutex
*/
-static void *cardmap_get(struct cardmap *map, unsigned int nr)
+
+/* get new free unit number and associate pointer with it */
+static int unit_get(struct idr *p, void *ptr)
{
- struct cardmap *p;
- int i;
+ int unit, err;
- for (p = map; p != NULL; ) {
- if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
- return NULL;
- if (p->shift == 0)
- return p->ptr[i];
- nr &= ~(CARDMAP_MASK << p->shift);
- p = p->ptr[i];
+again:
+ if (idr_pre_get(p, GFP_KERNEL) == 0) {
+ printk(KERN_ERR "Out of memory expanding drawable idr\n");
+ return -ENOMEM;
}
- return NULL;
-}
-static int cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
-{
- struct cardmap *p;
- int i;
+ err = idr_get_new_above(p, ptr, 0, &unit);
+ if (err == -EAGAIN)
+ goto again;
- p = *pmap;
- if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
- do {
- /* need a new top level */
- struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
- if (!np)
- goto enomem;
- np->ptr[0] = p;
- if (p != NULL) {
- np->shift = p->shift + CARDMAP_ORDER;
- p->parent = np;
- } else
- np->shift = 0;
- p = np;
- } while ((nr >> p->shift) >= CARDMAP_WIDTH);
- *pmap = p;
- }
- while (p->shift > 0) {
- i = (nr >> p->shift) & CARDMAP_MASK;
- if (p->ptr[i] == NULL) {
- struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
- if (!np)
- goto enomem;
- np->shift = p->shift - CARDMAP_ORDER;
- np->parent = p;
- p->ptr[i] = np;
- }
- if (ptr == NULL)
- clear_bit(i, &p->inuse);
- p = p->ptr[i];
- }
- i = nr & CARDMAP_MASK;
- p->ptr[i] = ptr;
- if (ptr != NULL)
- set_bit(i, &p->inuse);
- else
- clear_bit(i, &p->inuse);
- return 0;
- enomem:
- return -ENOMEM;
+ return unit;
}
-static unsigned int cardmap_find_first_free(struct cardmap *map)
+/* put unit number back to a pool */
+static void unit_put(struct idr *p, int n)
{
- struct cardmap *p;
- unsigned int nr = 0;
- int i;
-
- if ((p = map) == NULL)
- return 0;
- for (;;) {
- i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
- if (i >= CARDMAP_WIDTH) {
- if (p->parent == NULL)
- return CARDMAP_WIDTH << p->shift;
- p = p->parent;
- i = (nr >> p->shift) & CARDMAP_MASK;
- set_bit(i, &p->inuse);
- continue;
- }
- nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
- if (p->shift == 0 || p->ptr[i] == NULL)
- return nr;
- p = p->ptr[i];
- }
+ idr_remove(p, n);
}
-static void cardmap_destroy(struct cardmap **pmap)
+/* get pointer associated with the number */
+static void *unit_find(struct idr *p, int n)
{
- struct cardmap *p, *np;
- int i;
-
- for (p = *pmap; p != NULL; p = np) {
- if (p->shift != 0) {
- for (i = 0; i < CARDMAP_WIDTH; ++i)
- if (p->ptr[i] != NULL)
- break;
- if (i < CARDMAP_WIDTH) {
- np = p->ptr[i];
- p->ptr[i] = NULL;
- continue;
- }
- }
- np = p->parent;
- kfree(p);
- }
- *pmap = NULL;
+ return idr_find(p, n);
}
/* Module/initialization stuff */
projects / openwrt / staging / blogic.git / commitdiff