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Implemented collapsing forked vm_cache object chains when they become unused.

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This fixes bug #227 by closing that memory and semaphore leak.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@19041 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Axel Dörfler 2006-10-10 22:47:00 +00:00
parent bcf2f8133b
commit 4e4c58037e
1 changed files with 50 additions and 3 deletions
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53
src/system/kernel/vm/vm_cache.c
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@ -398,24 +398,71 @@ void
vm_cache_remove_consumer(vm_cache_ref *cacheRef, vm_cache *consumer)
{
vm_cache *cache = cacheRef->cache;
vm_cache *newSource = NULL;
TRACE(("remove consumer vm cache %p from cache %p\n", consumer, cache));
mutex_lock(&cacheRef->lock);
list_remove_item(&cache->consumers, consumer);
consumer->source = NULL;
if (cacheRef->areas == NULL && cache->source != NULL
&& !list_is_empty(&cache->consumers)
&& cache->consumers.link.next == cache->consumers.link.prev) {
// The cache is not really needed anymore - it can be merged with its only
// consumer left.
// TODO!
vm_cache_ref *consumerRef;
vm_page *page, *nextPage;
consumer = list_get_first_item(&cache->consumers);
consumerRef = consumer->ref;
mutex_lock(&consumerRef->lock);
// TODO: is it okay to lock them in this direction?
TRACE(("merge vm cache %p (ref == %ld) with vm cache %p\n",
cache, cacheRef->ref_count, cache->consumers.link.next));
cache, cacheRef->ref_count, consumer));
for (page = cache->page_list; page != NULL; page = nextPage) {
nextPage = page->cache_next;
vm_cache_remove_page(cacheRef, page);
if (vm_cache_lookup_page(consumerRef,
(off_t)page->cache_offset << PAGE_SHIFT) != NULL) {
// the page already is in the consumer cache - this copy is no
// longer needed, and can be freed
vm_page_set_state(page, PAGE_STATE_FREE);
continue;
}
// move the page into the consumer cache
vm_cache_insert_page(consumerRef, page,
(off_t)page->cache_offset << PAGE_SHIFT);
}
newSource = cache->source;
mutex_unlock(&consumerRef->lock);
}
mutex_unlock(&cacheRef->lock);
if (newSource != NULL) {
// The remaining consumer has gotten a new source
mutex_lock(&cacheRef->lock);
list_remove_item(&newSource->consumers, cache);
list_add_item(&newSource->consumers, consumer);
consumer->source = newSource;
cache->source = NULL;
mutex_unlock(&cacheRef->lock);
// Release the other reference to the cache - we take over
// its reference of its source cache
vm_cache_release_ref(cacheRef);
}
vm_cache_release_ref(cacheRef);
}