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-/*********************************************************************
- *
- * Filename: irqueue.c
- * Version: 0.3
- * Description: General queue implementation
- * Status: Experimental.
- * Author: Dag Brattli <dagb@cs.uit.no>
- * Created at: Tue Jun 9 13:29:31 1998
- * Modified at: Sun Dec 12 13:48:22 1999
- * Modified by: Dag Brattli <dagb@cs.uit.no>
- * Modified at: Thu Jan 4 14:29:10 CET 2001
- * Modified by: Marc Zyngier <mzyngier@freesurf.fr>
- *
- * Copyright (C) 1998-1999, Aage Kvalnes <aage@cs.uit.no>
- * Copyright (C) 1998, Dag Brattli,
- * All Rights Reserved.
- *
- * This code is taken from the Vortex Operating System written by Aage
- * Kvalnes. Aage has agreed that this code can use the GPL licence,
- * although he does not use that licence in his own code.
- *
- * This copyright does however _not_ include the ELF hash() function
- * which I currently don't know which licence or copyright it
- * has. Please inform me if you know.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2 of
- * the License, or (at your option) any later version.
- *
- * Neither Dag Brattli nor University of Tromsø admit liability nor
- * provide warranty for any of this software. This material is
- * provided "AS-IS" and at no charge.
- *
- ********************************************************************/
-
-/*
- * NOTE :
- * There are various problems with this package :
- * o the hash function for ints is pathetic (but could be changed)
- * o locking is sometime suspicious (especially during enumeration)
- * o most users have only a few elements (== overhead)
- * o most users never use search, so don't benefit from hashing
- * Problem already fixed :
- * o not 64 bit compliant (most users do hashv = (int) self)
- * o hashbin_remove() is broken => use hashbin_remove_this()
- * I think most users would be better served by a simple linked list
- * (like include/linux/list.h) with a global spinlock per list.
- * Jean II
- */
-
-/*
- * Notes on the concurrent access to hashbin and other SMP issues
- * -------------------------------------------------------------
- * Hashbins are very often in the IrDA stack a global repository of
- * information, and therefore used in a very asynchronous manner following
- * various events (driver calls, timers, user calls...).
- * Therefore, very often it is highly important to consider the
- * management of concurrent access to the hashbin and how to guarantee the
- * consistency of the operations on it.
- *
- * First, we need to define the objective of locking :
- * 1) Protect user data (content pointed by the hashbin)
- * 2) Protect hashbin structure itself (linked list in each bin)
- *
- * OLD LOCKING
- * -----------
- *
- * The previous locking strategy, either HB_LOCAL or HB_GLOBAL were
- * both inadequate in *both* aspect.
- * o HB_GLOBAL was using a spinlock for each bin (local locking).
- * o HB_LOCAL was disabling irq on *all* CPUs, so use a single
- * global semaphore.
- * The problems were :
- * A) Global irq disabling is no longer supported by the kernel
- * B) No protection for the hashbin struct global data
- * o hashbin_delete()
- * o hb_current
- * C) No protection for user data in some cases
- *
- * A) HB_LOCAL use global irq disabling, so doesn't work on kernel
- * 2.5.X. Even when it is supported (kernel 2.4.X and earlier), its
- * performance is not satisfactory on SMP setups. Most hashbins were
- * HB_LOCAL, so (A) definitely need fixing.
- * B) HB_LOCAL could be modified to fix (B). However, because HB_GLOBAL
- * lock only the individual bins, it will never be able to lock the
- * global data, so can't do (B).
- * C) Some functions return pointer to data that is still in the
- * hashbin :
- * o hashbin_find()
- * o hashbin_get_first()
- * o hashbin_get_next()
- * As the data is still in the hashbin, it may be changed or free'd
- * while the caller is examinimg the data. In those case, locking can't
- * be done within the hashbin, but must include use of the data within
- * the caller.
- * The caller can easily do this with HB_LOCAL (just disable irqs).
- * However, this is impossible with HB_GLOBAL because the caller has no
- * way to know the proper bin, so don't know which spinlock to use.
- *
- * Quick summary : can no longer use HB_LOCAL, and HB_GLOBAL is
- * fundamentally broken and will never work.
- *
- * NEW LOCKING
- * -----------
- *
- * To fix those problems, I've introduce a few changes in the
- * hashbin locking :
- * 1) New HB_LOCK scheme
- * 2) hashbin->hb_spinlock
- * 3) New hashbin usage policy
- *
- * HB_LOCK :
- * -------
- * HB_LOCK is a locking scheme intermediate between the old HB_LOCAL
- * and HB_GLOBAL. It uses a single spinlock to protect the whole content
- * of the hashbin. As it is a single spinlock, it can protect the global
- * data of the hashbin and not only the bins themselves.
- * HB_LOCK can only protect some of the hashbin calls, so it only lock
- * call that can be made 100% safe and leave other call unprotected.
- * HB_LOCK in theory is slower than HB_GLOBAL, but as the hashbin
- * content is always small contention is not high, so it doesn't matter
- * much. HB_LOCK is probably faster than HB_LOCAL.
- *
- * hashbin->hb_spinlock :
- * --------------------
- * The spinlock that HB_LOCK uses is available for caller, so that
- * the caller can protect unprotected calls (see below).
- * If the caller want to do entirely its own locking (HB_NOLOCK), he
- * can do so and may use safely this spinlock.
- * Locking is done like this :
- * spin_lock_irqsave(&hashbin->hb_spinlock, flags);
- * Releasing the lock :
- * spin_unlock_irqrestore(&hashbin->hb_spinlock, flags);
- *
- * Safe & Protected calls :
- * ----------------------
- * The following calls are safe or protected via HB_LOCK :
- * o hashbin_new() -> safe
- * o hashbin_delete()
- * o hashbin_insert()
- * o hashbin_remove_first()
- * o hashbin_remove()
- * o hashbin_remove_this()
- * o HASHBIN_GET_SIZE() -> atomic
- *
- * The following calls only protect the hashbin itself :
- * o hashbin_lock_find()
- * o hashbin_find_next()
- *
- * Unprotected calls :
- * -----------------
- * The following calls need to be protected by the caller :
- * o hashbin_find()
- * o hashbin_get_first()
- * o hashbin_get_next()
- *
- * Locking Policy :
- * --------------
- * If the hashbin is used only in a single thread of execution
- * (explicitly or implicitely), you can use HB_NOLOCK
- * If the calling module already provide concurrent access protection,
- * you may use HB_NOLOCK.
- *
- * In all other cases, you need to use HB_LOCK and lock the hashbin
- * every time before calling one of the unprotected calls. You also must
- * use the pointer returned by the unprotected call within the locked
- * region.
- *
- * Extra care for enumeration :
- * --------------------------
- * hashbin_get_first() and hashbin_get_next() use the hashbin to
- * store the current position, in hb_current.
- * As long as the hashbin remains locked, this is safe. If you unlock
- * the hashbin, the current position may change if anybody else modify
- * or enumerate the hashbin.
- * Summary : do the full enumeration while locked.
- *
- * Alternatively, you may use hashbin_find_next(). But, this will
- * be slower, is more complex to use and doesn't protect the hashbin
- * content. So, care is needed here as well.
- *
- * Other issues :
- * ------------
- * I believe that we are overdoing it by using spin_lock_irqsave()
- * and we should use only spin_lock_bh() or similar. But, I don't have
- * the balls to try it out.
- * Don't believe that because hashbin are now (somewhat) SMP safe
- * that the rest of the code is. Higher layers tend to be safest,
- * but LAP and LMP would need some serious dedicated love.
- *
- * Jean II
- */
-#include <linux/module.h>
-#include <linux/slab.h>
-
-#include <net/irda/irda.h>
-#include <net/irda/irqueue.h>
-
-/************************ QUEUE SUBROUTINES ************************/
-
-/*
- * Hashbin
- */
-#define GET_HASHBIN(x) ( x & HASHBIN_MASK )
-
-/*
- * Function hash (name)
- *
- * This function hash the input string 'name' using the ELF hash
- * function for strings.
- */
-static __u32 hash( const char* name)
-{
- __u32 h = 0;
- __u32 g;
-
- while(*name) {
- h = (h<<4) + *name++;
- if ((g = (h & 0xf0000000)))
- h ^=g>>24;
- h &=~g;
- }
- return h;
-}
-
-/*
- * Function enqueue_first (queue, proc)
- *
- * Insert item first in queue.
- *
- */
-static void enqueue_first(irda_queue_t **queue, irda_queue_t* element)
-{
-
- /*
- * Check if queue is empty.
- */
- if ( *queue == NULL ) {
- /*
- * Queue is empty. Insert one element into the queue.
- */
- element->q_next = element->q_prev = *queue = element;
-
- } else {
- /*
- * Queue is not empty. Insert element into front of queue.
- */
- element->q_next = (*queue);
- (*queue)->q_prev->q_next = element;
- element->q_prev = (*queue)->q_prev;
- (*queue)->q_prev = element;
- (*queue) = element;
- }
-}
-
-
-/*
- * Function dequeue (queue)
- *
- * Remove first entry in queue
- *
- */
-static irda_queue_t *dequeue_first(irda_queue_t **queue)
-{
- irda_queue_t *ret;
-
- pr_debug("dequeue_first()\n");
-
- /*
- * Set return value
- */
- ret = *queue;
-
- if ( *queue == NULL ) {
- /*
- * Queue was empty.
- */
- } else if ( (*queue)->q_next == *queue ) {
- /*
- * Queue only contained a single element. It will now be
- * empty.
- */
- *queue = NULL;
- } else {
- /*
- * Queue contained several element. Remove the first one.
- */
- (*queue)->q_prev->q_next = (*queue)->q_next;
- (*queue)->q_next->q_prev = (*queue)->q_prev;
- *queue = (*queue)->q_next;
- }
-
- /*
- * Return the removed entry (or NULL of queue was empty).
- */
- return ret;
-}
-
-/*
- * Function dequeue_general (queue, element)
- *
- *
- */
-static irda_queue_t *dequeue_general(irda_queue_t **queue, irda_queue_t* element)
-{
- irda_queue_t *ret;
-
- pr_debug("dequeue_general()\n");
-
- /*
- * Set return value
- */
- ret = *queue;
-
- if ( *queue == NULL ) {
- /*
- * Queue was empty.
- */
- } else if ( (*queue)->q_next == *queue ) {
- /*
- * Queue only contained a single element. It will now be
- * empty.
- */
- *queue = NULL;
-
- } else {
- /*
- * Remove specific element.
- */
- element->q_prev->q_next = element->q_next;
- element->q_next->q_prev = element->q_prev;
- if ( (*queue) == element)
- (*queue) = element->q_next;
- }
-
- /*
- * Return the removed entry (or NULL of queue was empty).
- */
- return ret;
-}
-
-/************************ HASHBIN MANAGEMENT ************************/
-
-/*
- * Function hashbin_create ( type, name )
- *
- * Create hashbin!
- *
- */
-hashbin_t *hashbin_new(int type)
-{
- hashbin_t* hashbin;
-
- /*
- * Allocate new hashbin
- */
- hashbin = kzalloc(sizeof(*hashbin), GFP_ATOMIC);
- if (!hashbin)
- return NULL;
-
- /*
- * Initialize structure
- */
- hashbin->hb_type = type;
- hashbin->magic = HB_MAGIC;
- //hashbin->hb_current = NULL;
-
- /* Make sure all spinlock's are unlocked */
- if ( hashbin->hb_type & HB_LOCK ) {
- spin_lock_init(&hashbin->hb_spinlock);
- }
-
- return hashbin;
-}
-EXPORT_SYMBOL(hashbin_new);
-
-
-/*
- * Function hashbin_delete (hashbin, free_func)
- *
- * Destroy hashbin, the free_func can be a user supplied special routine
- * for deallocating this structure if it's complex. If not the user can
- * just supply kfree, which should take care of the job.
- */
-int hashbin_delete( hashbin_t* hashbin, FREE_FUNC free_func)
-{
- irda_queue_t* queue;
- unsigned long flags = 0;
- int i;
-
- IRDA_ASSERT(hashbin != NULL, return -1;);
- IRDA_ASSERT(hashbin->magic == HB_MAGIC, return -1;);
-
- /* Synchronize */
- if (hashbin->hb_type & HB_LOCK)
- spin_lock_irqsave(&hashbin->hb_spinlock, flags);
-
- /*
- * Free the entries in the hashbin, TODO: use hashbin_clear when
- * it has been shown to work
- */
- for (i = 0; i < HASHBIN_SIZE; i ++ ) {
- while (1) {
- queue = dequeue_first((irda_queue_t**) &hashbin->hb_queue[i]);
-
- if (!queue)
- break;
-
- if (free_func) {
- if (hashbin->hb_type & HB_LOCK)
- spin_unlock_irqrestore(&hashbin->hb_spinlock, flags);
- free_func(queue);
- if (hashbin->hb_type & HB_LOCK)
- spin_lock_irqsave(&hashbin->hb_spinlock, flags);
- }
- }
- }
-
- /* Cleanup local data */
- hashbin->hb_current = NULL;
- hashbin->magic = ~HB_MAGIC;
-
- /* Release lock */
- if (hashbin->hb_type & HB_LOCK)
- spin_unlock_irqrestore(&hashbin->hb_spinlock, flags);
-
- /*
- * Free the hashbin structure
- */
- kfree(hashbin);
-
- return 0;
-}
-EXPORT_SYMBOL(hashbin_delete);
-
-/********************* HASHBIN LIST OPERATIONS *********************/
-
-/*
- * Function hashbin_insert (hashbin, entry, name)
- *
- * Insert an entry into the hashbin
- *
- */
-void hashbin_insert(hashbin_t* hashbin, irda_queue_t* entry, long hashv,
- const char* name)
-{
- unsigned long flags = 0;
- int bin;
-
- IRDA_ASSERT( hashbin != NULL, return;);
- IRDA_ASSERT( hashbin->magic == HB_MAGIC, return;);
-
- /*
- * Locate hashbin
- */
- if ( name )
- hashv = hash( name );
- bin = GET_HASHBIN( hashv );
-
- /* Synchronize */
- if ( hashbin->hb_type & HB_LOCK ) {
- spin_lock_irqsave(&hashbin->hb_spinlock, flags);
- } /* Default is no-lock */
-
- /*
- * Store name and key
- */
- entry->q_hash = hashv;
- if ( name )
- strlcpy( entry->q_name, name, sizeof(entry->q_name));
-
- /*
- * Insert new entry first
- */
- enqueue_first( (irda_queue_t**) &hashbin->hb_queue[ bin ],
- entry);
- hashbin->hb_size++;
-
- /* Release lock */
- if ( hashbin->hb_type & HB_LOCK ) {
- spin_unlock_irqrestore(&hashbin->hb_spinlock, flags);
- } /* Default is no-lock */
-}
-EXPORT_SYMBOL(hashbin_insert);
-
-/*
- * Function hashbin_remove_first (hashbin)
- *
- * Remove first entry of the hashbin
- *
- * Note : this function no longer use hashbin_remove(), but does things
- * similar to hashbin_remove_this(), so can be considered safe.
- * Jean II
- */
-void *hashbin_remove_first( hashbin_t *hashbin)
-{
- unsigned long flags = 0;
- irda_queue_t *entry = NULL;
-
- /* Synchronize */
- if ( hashbin->hb_type & HB_LOCK ) {
- spin_lock_irqsave(&hashbin->hb_spinlock, flags);
- } /* Default is no-lock */
-
- entry = hashbin_get_first( hashbin);
- if ( entry != NULL) {
- int bin;
- long hashv;
- /*
- * Locate hashbin
- */
- hashv = entry->q_hash;
- bin = GET_HASHBIN( hashv );
-
- /*
- * Dequeue the entry...
- */
- dequeue_general( (irda_queue_t**) &hashbin->hb_queue[ bin ],
- entry);
- hashbin->hb_size--;
- entry->q_next = NULL;
- entry->q_prev = NULL;
-
- /*
- * Check if this item is the currently selected item, and in
- * that case we must reset hb_current
- */
- if ( entry == hashbin->hb_current)
- hashbin->hb_current = NULL;
- }
-
- /* Release lock */
- if ( hashbin->hb_type & HB_LOCK ) {
- spin_unlock_irqrestore(&hashbin->hb_spinlock, flags);
- } /* Default is no-lock */
-
- return entry;
-}
-
-
-/*
- * Function hashbin_remove (hashbin, hashv, name)
- *
- * Remove entry with the given name
- *
- * The use of this function is highly discouraged, because the whole
- * concept behind hashbin_remove() is broken. In many cases, it's not
- * possible to guarantee the unicity of the index (either hashv or name),
- * leading to removing the WRONG entry.
- * The only simple safe use is :
- * hashbin_remove(hasbin, (int) self, NULL);
- * In other case, you must think hard to guarantee unicity of the index.
- * Jean II
- */
-void* hashbin_remove( hashbin_t* hashbin, long hashv, const char* name)
-{
- int bin, found = FALSE;
- unsigned long flags = 0;
- irda_queue_t* entry;
-
- IRDA_ASSERT( hashbin != NULL, return NULL;);
- IRDA_ASSERT( hashbin->magic == HB_MAGIC, return NULL;);
-
- /*
- * Locate hashbin
- */
- if ( name )
- hashv = hash( name );
- bin = GET_HASHBIN( hashv );
-
- /* Synchronize */
- if ( hashbin->hb_type & HB_LOCK ) {
- spin_lock_irqsave(&hashbin->hb_spinlock, flags);
- } /* Default is no-lock */
-
- /*
- * Search for entry
- */
- entry = hashbin->hb_queue[ bin ];
- if ( entry ) {
- do {
- /*
- * Check for key
- */
- if ( entry->q_hash == hashv ) {
- /*
- * Name compare too?
- */
- if ( name ) {
- if ( strcmp( entry->q_name, name) == 0)
- {
- found = TRUE;
- break;
- }
- } else {
- found = TRUE;
- break;
- }
- }
- entry = entry->q_next;
- } while ( entry != hashbin->hb_queue[ bin ] );
- }
-
- /*
- * If entry was found, dequeue it
- */
- if ( found ) {
- dequeue_general( (irda_queue_t**) &hashbin->hb_queue[ bin ],
- entry);
- hashbin->hb_size--;
-
- /*
- * Check if this item is the currently selected item, and in
- * that case we must reset hb_current
- */
- if ( entry == hashbin->hb_current)
- hashbin->hb_current = NULL;
- }
-
- /* Release lock */
- if ( hashbin->hb_type & HB_LOCK ) {
- spin_unlock_irqrestore(&hashbin->hb_spinlock, flags);
- } /* Default is no-lock */
-
-
- /* Return */
- if ( found )
- return entry;
- else
- return NULL;
-
-}
-EXPORT_SYMBOL(hashbin_remove);
-
-/*
- * Function hashbin_remove_this (hashbin, entry)
- *
- * Remove entry with the given name
- *
- * In some cases, the user of hashbin can't guarantee the unicity
- * of either the hashv or name.
- * In those cases, using the above function is guaranteed to cause troubles,
- * so we use this one instead...
- * And by the way, it's also faster, because we skip the search phase ;-)
- */
-void* hashbin_remove_this( hashbin_t* hashbin, irda_queue_t* entry)
-{
- unsigned long flags = 0;
- int bin;
- long hashv;
-
- IRDA_ASSERT( hashbin != NULL, return NULL;);
- IRDA_ASSERT( hashbin->magic == HB_MAGIC, return NULL;);
- IRDA_ASSERT( entry != NULL, return NULL;);
-
- /* Synchronize */
- if ( hashbin->hb_type & HB_LOCK ) {
- spin_lock_irqsave(&hashbin->hb_spinlock, flags);
- } /* Default is no-lock */
-
- /* Check if valid and not already removed... */
- if((entry->q_next == NULL) || (entry->q_prev == NULL)) {
- entry = NULL;
- goto out;
- }
-
- /*
- * Locate hashbin
- */
- hashv = entry->q_hash;
- bin = GET_HASHBIN( hashv );
-
- /*
- * Dequeue the entry...
- */
- dequeue_general( (irda_queue_t**) &hashbin->hb_queue[ bin ],
- entry);
- hashbin->hb_size--;
- entry->q_next = NULL;
- entry->q_prev = NULL;
-
- /*
- * Check if this item is the currently selected item, and in
- * that case we must reset hb_current
- */
- if ( entry == hashbin->hb_current)
- hashbin->hb_current = NULL;
-out:
- /* Release lock */
- if ( hashbin->hb_type & HB_LOCK ) {
- spin_unlock_irqrestore(&hashbin->hb_spinlock, flags);
- } /* Default is no-lock */
-
- return entry;
-}
-EXPORT_SYMBOL(hashbin_remove_this);
-
-/*********************** HASHBIN ENUMERATION ***********************/
-
-/*
- * Function hashbin_common_find (hashbin, hashv, name)
- *
- * Find item with the given hashv or name
- *
- */
-void* hashbin_find( hashbin_t* hashbin, long hashv, const char* name )
-{
- int bin;
- irda_queue_t* entry;
-
- pr_debug("hashbin_find()\n");
-
- IRDA_ASSERT( hashbin != NULL, return NULL;);
- IRDA_ASSERT( hashbin->magic == HB_MAGIC, return NULL;);
-
- /*
- * Locate hashbin
- */
- if ( name )
- hashv = hash( name );
- bin = GET_HASHBIN( hashv );
-
- /*
- * Search for entry
- */
- entry = hashbin->hb_queue[ bin];
- if ( entry ) {
- do {
- /*
- * Check for key
- */
- if ( entry->q_hash == hashv ) {
- /*
- * Name compare too?
- */
- if ( name ) {
- if ( strcmp( entry->q_name, name ) == 0 ) {
- return entry;
- }
- } else {
- return entry;
- }
- }
- entry = entry->q_next;
- } while ( entry != hashbin->hb_queue[ bin ] );
- }
-
- return NULL;
-}
-EXPORT_SYMBOL(hashbin_find);
-
-/*
- * Function hashbin_lock_find (hashbin, hashv, name)
- *
- * Find item with the given hashv or name
- *
- * Same, but with spinlock protection...
- * I call it safe, but it's only safe with respect to the hashbin, not its
- * content. - Jean II
- */
-void* hashbin_lock_find( hashbin_t* hashbin, long hashv, const char* name )
-{
- unsigned long flags = 0;
- irda_queue_t* entry;
-
- /* Synchronize */
- spin_lock_irqsave(&hashbin->hb_spinlock, flags);
-
- /*
- * Search for entry
- */
- entry = hashbin_find(hashbin, hashv, name);
-
- /* Release lock */
- spin_unlock_irqrestore(&hashbin->hb_spinlock, flags);
-
- return entry;
-}
-EXPORT_SYMBOL(hashbin_lock_find);
-
-/*
- * Function hashbin_find (hashbin, hashv, name, pnext)
- *
- * Find an item with the given hashv or name, and its successor
- *
- * This function allow to do concurrent enumerations without the
- * need to lock over the whole session, because the caller keep the
- * context of the search. On the other hand, it might fail and return
- * NULL if the entry is removed. - Jean II
- */
-void* hashbin_find_next( hashbin_t* hashbin, long hashv, const char* name,
- void ** pnext)
-{
- unsigned long flags = 0;
- irda_queue_t* entry;
-
- /* Synchronize */
- spin_lock_irqsave(&hashbin->hb_spinlock, flags);
-
- /*
- * Search for current entry
- * This allow to check if the current item is still in the
- * hashbin or has been removed.
- */
- entry = hashbin_find(hashbin, hashv, name);
-
- /*
- * Trick hashbin_get_next() to return what we want
- */
- if(entry) {
- hashbin->hb_current = entry;
- *pnext = hashbin_get_next( hashbin );
- } else
- *pnext = NULL;
-
- /* Release lock */
- spin_unlock_irqrestore(&hashbin->hb_spinlock, flags);
-
- return entry;
-}
-
-/*
- * Function hashbin_get_first (hashbin)
- *
- * Get a pointer to first element in hashbin, this function must be
- * called before any calls to hashbin_get_next()!
- *
- */
-irda_queue_t *hashbin_get_first( hashbin_t* hashbin)
-{
- irda_queue_t *entry;
- int i;
-
- IRDA_ASSERT( hashbin != NULL, return NULL;);
- IRDA_ASSERT( hashbin->magic == HB_MAGIC, return NULL;);
-
- if ( hashbin == NULL)
- return NULL;
-
- for ( i = 0; i < HASHBIN_SIZE; i ++ ) {
- entry = hashbin->hb_queue[ i];
- if ( entry) {
- hashbin->hb_current = entry;
- return entry;
- }
- }
- /*
- * Did not find any item in hashbin
- */
- return NULL;
-}
-EXPORT_SYMBOL(hashbin_get_first);
-
-/*
- * Function hashbin_get_next (hashbin)
- *
- * Get next item in hashbin. A series of hashbin_get_next() calls must
- * be started by a call to hashbin_get_first(). The function returns
- * NULL when all items have been traversed
- *
- * The context of the search is stored within the hashbin, so you must
- * protect yourself from concurrent enumerations. - Jean II
- */
-irda_queue_t *hashbin_get_next( hashbin_t *hashbin)
-{
- irda_queue_t* entry;
- int bin;
- int i;
-
- IRDA_ASSERT( hashbin != NULL, return NULL;);
- IRDA_ASSERT( hashbin->magic == HB_MAGIC, return NULL;);
-
- if ( hashbin->hb_current == NULL) {
- IRDA_ASSERT( hashbin->hb_current != NULL, return NULL;);
- return NULL;
- }
- entry = hashbin->hb_current->q_next;
- bin = GET_HASHBIN( entry->q_hash);
-
- /*
- * Make sure that we are not back at the beginning of the queue
- * again
- */
- if ( entry != hashbin->hb_queue[ bin ]) {
- hashbin->hb_current = entry;
-
- return entry;
- }
-
- /*
- * Check that this is not the last queue in hashbin
- */
- if ( bin >= HASHBIN_SIZE)
- return NULL;
-
- /*
- * Move to next queue in hashbin
- */
- bin++;
- for ( i = bin; i < HASHBIN_SIZE; i++ ) {
- entry = hashbin->hb_queue[ i];
- if ( entry) {
- hashbin->hb_current = entry;
-
- return entry;
- }
- }
- return NULL;
-}
-EXPORT_SYMBOL(hashbin_get_next);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.