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net: ppp_generic - use idr technique instead of cardmaps
Use idr technique instead of own implemented cardmaps. It saves us a number of lines and gives an ability to use library functions. Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Cyrill Gorcunov
David S. Miller
parent
c0700f90e5
commit
7a95d267fb
@ -27,6 +27,7 @@
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#include <linux/kmod.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <linux/idr.h>
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#include <linux/netdevice.h>
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#include <linux/poll.h>
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#include <linux/ppp_defs.h>
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@ -171,36 +172,14 @@ struct channel {
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* channel.downl.
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*/
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/*
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* A cardmap represents a mapping from unsigned integers to pointers,
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* and provides a fast "find lowest unused number" operation.
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* It uses a broad (32-way) tree with a bitmap at each level.
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* It is designed to be space-efficient for small numbers of entries
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* and time-efficient for large numbers of entries.
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*/
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#define CARDMAP_ORDER 5
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#define CARDMAP_WIDTH (1U << CARDMAP_ORDER)
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#define CARDMAP_MASK (CARDMAP_WIDTH - 1)
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struct cardmap {
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int shift;
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unsigned long inuse;
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struct cardmap *parent;
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void *ptr[CARDMAP_WIDTH];
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};
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static void *cardmap_get(struct cardmap *map, unsigned int nr);
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static int cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
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static unsigned int cardmap_find_first_free(struct cardmap *map);
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static void cardmap_destroy(struct cardmap **map);
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/*
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* all_ppp_mutex protects the all_ppp_units mapping.
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* It also ensures that finding a ppp unit in the all_ppp_units map
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* and updating its file.refcnt field is atomic.
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*/
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static DEFINE_MUTEX(all_ppp_mutex);
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static struct cardmap *all_ppp_units;
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static atomic_t ppp_unit_count = ATOMIC_INIT(0);
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static struct idr ppp_units_idr;
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/*
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* all_channels_lock protects all_channels and last_channel_index,
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@ -269,6 +248,9 @@ static struct channel *ppp_find_channel(int unit);
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static int ppp_connect_channel(struct channel *pch, int unit);
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static int ppp_disconnect_channel(struct channel *pch);
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static void ppp_destroy_channel(struct channel *pch);
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static int unit_get(struct idr *p, void *ptr);
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static void unit_put(struct idr *p, int n);
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static void *unit_find(struct idr *p, int n);
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static struct class *ppp_class;
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@ -870,6 +852,8 @@ static int __init ppp_init(void)
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"ppp");
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}
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idr_init(&ppp_units_idr);
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out:
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if (err)
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printk(KERN_ERR "failed to register PPP device (%d)\n", err);
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@ -2440,10 +2424,22 @@ ppp_create_interface(int unit, int *retp)
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ret = -EEXIST;
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mutex_lock(&all_ppp_mutex);
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if (unit < 0)
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unit = cardmap_find_first_free(all_ppp_units);
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else if (cardmap_get(all_ppp_units, unit) != NULL)
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if (unit < 0) {
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unit = unit_get(&ppp_units_idr, ppp);
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if (unit < 0) {
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*retp = unit;
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goto out2;
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}
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} else {
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if (unit_find(&ppp_units_idr, unit))
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goto out2; /* unit already exists */
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else {
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/* darn, someone is cheatting us? */
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*retp = -EINVAL;
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goto out2;
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}
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}
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/* Initialize the new ppp unit */
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ppp->file.index = unit;
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@ -2451,23 +2447,18 @@ ppp_create_interface(int unit, int *retp)
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ret = register_netdev(dev);
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if (ret != 0) {
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unit_put(&ppp_units_idr, unit);
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printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
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dev->name, ret);
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goto out2;
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}
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atomic_inc(&ppp_unit_count);
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ret = cardmap_set(&all_ppp_units, unit, ppp);
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if (ret != 0)
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goto out3;
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mutex_unlock(&all_ppp_mutex);
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*retp = 0;
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return ppp;
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out3:
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atomic_dec(&ppp_unit_count);
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unregister_netdev(dev);
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out2:
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mutex_unlock(&all_ppp_mutex);
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free_netdev(dev);
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@ -2507,7 +2498,7 @@ static void ppp_shutdown_interface(struct ppp *ppp)
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unregister_netdev(dev);
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free_netdev(dev);
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}
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cardmap_set(&all_ppp_units, ppp->file.index, NULL);
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unit_put(&ppp_units_idr, ppp->file.index);
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ppp->file.dead = 1;
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ppp->owner = NULL;
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wake_up_interruptible(&ppp->file.rwait);
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@ -2561,7 +2552,7 @@ static void ppp_destroy_interface(struct ppp *ppp)
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static struct ppp *
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ppp_find_unit(int unit)
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{
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return cardmap_get(all_ppp_units, unit);
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return unit_find(&ppp_units_idr, unit);
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}
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/*
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@ -2679,123 +2670,45 @@ static void __exit ppp_cleanup(void)
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/* should never happen */
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if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
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printk(KERN_ERR "PPP: removing module but units remain!\n");
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cardmap_destroy(&all_ppp_units);
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unregister_chrdev(PPP_MAJOR, "ppp");
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device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
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class_destroy(ppp_class);
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idr_destroy(&ppp_units_idr);
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}
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/*
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* Cardmap implementation.
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* Units handling. Caller must protect concurrent access
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* by holding all_ppp_mutex
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*/
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static void *cardmap_get(struct cardmap *map, unsigned int nr)
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/* get new free unit number and associate pointer with it */
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static int unit_get(struct idr *p, void *ptr)
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{
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struct cardmap *p;
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int i;
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int unit, err;
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for (p = map; p != NULL; ) {
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if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
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return NULL;
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if (p->shift == 0)
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return p->ptr[i];
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nr &= ~(CARDMAP_MASK << p->shift);
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p = p->ptr[i];
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}
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return NULL;
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}
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static int cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
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{
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struct cardmap *p;
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int i;
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p = *pmap;
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if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
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do {
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/* need a new top level */
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struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
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if (!np)
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goto enomem;
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np->ptr[0] = p;
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if (p != NULL) {
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np->shift = p->shift + CARDMAP_ORDER;
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p->parent = np;
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} else
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np->shift = 0;
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p = np;
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} while ((nr >> p->shift) >= CARDMAP_WIDTH);
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*pmap = p;
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}
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while (p->shift > 0) {
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i = (nr >> p->shift) & CARDMAP_MASK;
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if (p->ptr[i] == NULL) {
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struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
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if (!np)
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goto enomem;
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np->shift = p->shift - CARDMAP_ORDER;
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np->parent = p;
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p->ptr[i] = np;
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}
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if (ptr == NULL)
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clear_bit(i, &p->inuse);
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p = p->ptr[i];
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}
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i = nr & CARDMAP_MASK;
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p->ptr[i] = ptr;
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if (ptr != NULL)
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set_bit(i, &p->inuse);
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else
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clear_bit(i, &p->inuse);
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return 0;
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enomem:
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again:
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if (idr_pre_get(p, GFP_KERNEL) == 0) {
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printk(KERN_ERR "Out of memory expanding drawable idr\n");
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return -ENOMEM;
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}
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err = idr_get_new_above(p, ptr, 0, &unit);
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if (err == -EAGAIN)
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goto again;
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return unit;
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}
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static unsigned int cardmap_find_first_free(struct cardmap *map)
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/* put unit number back to a pool */
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static void unit_put(struct idr *p, int n)
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{
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struct cardmap *p;
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unsigned int nr = 0;
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int i;
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if ((p = map) == NULL)
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return 0;
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for (;;) {
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i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
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if (i >= CARDMAP_WIDTH) {
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if (p->parent == NULL)
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return CARDMAP_WIDTH << p->shift;
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p = p->parent;
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i = (nr >> p->shift) & CARDMAP_MASK;
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set_bit(i, &p->inuse);
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continue;
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}
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nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
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if (p->shift == 0 || p->ptr[i] == NULL)
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return nr;
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p = p->ptr[i];
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}
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idr_remove(p, n);
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}
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static void cardmap_destroy(struct cardmap **pmap)
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/* get pointer associated with the number */
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static void *unit_find(struct idr *p, int n)
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{
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struct cardmap *p, *np;
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int i;
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for (p = *pmap; p != NULL; p = np) {
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if (p->shift != 0) {
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for (i = 0; i < CARDMAP_WIDTH; ++i)
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if (p->ptr[i] != NULL)
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break;
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if (i < CARDMAP_WIDTH) {
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np = p->ptr[i];
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p->ptr[i] = NULL;
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continue;
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}
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}
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np = p->parent;
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kfree(p);
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}
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*pmap = NULL;
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return idr_find(p, n);
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}
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/* Module/initialization stuff */
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