From 529bf1c6d767f08bf5f84d80b132119441a67085 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Axel=20D=C3=B6rfler?= <axeld@pinc-software.de>
Date: Wed, 28 Dec 2005 16:40:05 +0000
Subject: [PATCH] block_range::Delete() did not remove the block_range from the
 free list, and thus, it could be used again which led to a crash. Changed the
 free ranges list from a singly linked list to a doubly linked list so that
 not all free ranges have to be searched for the one to be freed anymore.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@15696 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 src/system/kernel/cache/block_allocator.cpp   | 25 +++++--------------
 src/system/kernel/cache/block_cache.cpp       |  7 +++---
 src/system/kernel/cache/block_cache_private.h | 10 ++++++--
 3 files changed, 17 insertions(+), 25 deletions(-)

diff --git a/src/system/kernel/cache/block_allocator.cpp b/src/system/kernel/cache/block_allocator.cpp
index de6de70ea0..17da1330df 100644
--- a/src/system/kernel/cache/block_allocator.cpp
+++ b/src/system/kernel/cache/block_allocator.cpp
@@ -201,8 +201,7 @@ block_range::New(block_cache *cache, block_range **_range)
 	range->base = address;
 
 	// insert into free ranges list in cache
-	range->free_next = cache->free_ranges;
-	cache->free_ranges = range;
+	cache->free_ranges.Add(range);
 
 	*_range = range;
 	return B_OK;
@@ -236,6 +235,9 @@ block_range::Delete(block_cache *cache, block_range *range)
 		vm_page_set_state(range->pages[i], PAGE_STATE_FREE);
 	}
 
+	// remove from cache free list
+	cache->free_ranges.Remove(range);
+
 	free(range);
 }
 
@@ -376,21 +378,7 @@ block_range::Allocate(block_cache *cache, block_chunk **_chunk)
 
 		if (used_mask == cache->range_mask) {
 			// range is full, remove it from the free list
-
-			// usually, the first entry will be ourself, but we don't count on it
-			block_range *last = NULL, *range = cache->free_ranges;
-			while (range != NULL && range != this) {
-				last = range;
-				range = range->free_next;
-			}
-			if (range == NULL) {
-				panic("block_range %p was free but not in the free list\n", this);
-			} else {
-				if (last)
-					last->free_next = free_next;
-				else
-					cache->free_ranges = free_next;
-			}
+			cache->free_ranges.Remove(this);
 		}
 	}
 	TRACE(("Allocate: used masks: chunk = %x, range = %lx\n", chunks[chunk].used_mask, used_mask));
@@ -409,8 +397,7 @@ block_range::Free(block_cache *cache, void *address)
 	if (chunks[chunk].used_mask == cache->chunk_mask) {
 		if (used_mask == cache->range_mask) {
 			// range was full before, add it to the free list
-			free_next = cache->free_ranges;
-			cache->free_ranges = this;
+			cache->free_ranges.Add(this);
 		}
 		// chunk was full before, propagate usage bit to range
 		used_mask &= ~(1UL << chunk);
diff --git a/src/system/kernel/cache/block_cache.cpp b/src/system/kernel/cache/block_cache.cpp
index edd3c07a95..1b2df13ebe 100644
--- a/src/system/kernel/cache/block_cache.cpp
+++ b/src/system/kernel/cache/block_cache.cpp
@@ -153,8 +153,7 @@ block_cache::block_cache(int _fd, off_t numBlocks, size_t blockSize)
 	next_transaction_id(1),
 	last_transaction(NULL),
 	transaction_hash(NULL),
-	ranges_hash(NULL),
-	free_ranges(NULL)
+	ranges_hash(NULL)
 {
 	hash = hash_init(32, 0, &cached_block::Compare, &cached_block::Hash);
 	if (hash == NULL)
@@ -208,8 +207,8 @@ block_cache::InitCheck()
 block_range *
 block_cache::GetFreeRange()
 {
-	if (free_ranges != NULL)
-		return free_ranges;
+	if (!free_ranges.IsEmpty())
+		return free_ranges.First();
 
 	// we need to allocate a new range
 	block_range *range;
diff --git a/src/system/kernel/cache/block_cache_private.h b/src/system/kernel/cache/block_cache_private.h
index 965806044f..f3d368b96b 100644
--- a/src/system/kernel/cache/block_cache_private.h
+++ b/src/system/kernel/cache/block_cache_private.h
@@ -25,7 +25,9 @@ struct cache_transaction;
 struct cached_block;
 struct block_chunk;
 struct block_cache;
+struct block_range;
 typedef DoublyLinkedListLink<cached_block> block_link;
+typedef DoublyLinkedListLink<block_range> range_link;
 
 
 struct cached_block {
@@ -66,7 +68,7 @@ struct block_chunk {
 
 struct block_range {
 	block_range		*next;			// next in hash
-	block_range		*free_next;
+	range_link		link;
 	addr_t			base;
 	uint32			used_mask;
 	vm_page			*pages[kNumBlockRangePages];
@@ -91,6 +93,10 @@ struct block_range {
 	static uint32 Hash(void *_blockRange, const void *_address, uint32 range);
 };
 
+typedef DoublyLinkedList<block_range,
+	DoublyLinkedListMemberGetLink<block_range,
+		&block_range::link> > range_list;
+
 struct block_cache {
 	hash_table	*hash;
 	benaphore	lock;
@@ -102,7 +108,7 @@ struct block_cache {
 	hash_table	*transaction_hash;
 
 	hash_table	*ranges_hash;
-	block_range	*free_ranges;
+	range_list	free_ranges;
 	uint32		chunks_per_range;
 	size_t		chunk_size;
 	uint32		range_mask;