irqueue.c 22.7 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921
/*********************************************************************
 *
 * 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)
{

	IRDA_DEBUG( 4, "%s()\n", __func__);

	/*
	 * 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;

	IRDA_DEBUG( 4, "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;

	IRDA_DEBUG( 4, "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.
 */
#ifdef CONFIG_LOCKDEP
static int hashbin_lock_depth = 0;
#endif
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_nested(&hashbin->hb_spinlock, flags,
					 hashbin_lock_depth++);
	}

	/*
	 *  Free the entries in the hashbin, TODO: use hashbin_clear when
	 *  it has been shown to work
	 */
	for (i = 0; i < HASHBIN_SIZE; i ++ ) {
		queue = dequeue_first((irda_queue_t**) &hashbin->hb_queue[i]);
		while (queue ) {
			if (free_func)
				(*free_func)(queue);
			queue = dequeue_first(
				(irda_queue_t**) &hashbin->hb_queue[i]);
		}
	}

	/* 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);
#ifdef CONFIG_LOCKDEP
		hashbin_lock_depth--;
#endif
	}

	/*
	 *  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_DEBUG( 4, "%s()\n", __func__);

	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_DEBUG( 4, "%s()\n", __func__);

	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_DEBUG( 4, "%s()\n", __func__);

	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;

	IRDA_DEBUG( 4, "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);