project-base/server-skynet-source-3rd-jemalloc
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Fix another deadlock related to chunk_record().

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Fix chunk_record() to unlock chunks_mtx before deallocating a base
node, in order to avoid potential deadlock.  This fix addresses the
second of two similar bugs.
This commit is contained in:
Jason Evans 2013-04-22 22:36:18 -07:00
parent 741fbc6ba4
commit 4f929aa948
1 changed files with 11 additions and 8 deletions
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19
src/chunk.c
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@ -214,7 +214,7 @@ chunk_record(extent_tree_t *chunks_szad, extent_tree_t *chunks_ad, void *chunk,
size_t size) size_t size)
{ {
bool unzeroed; bool unzeroed;
extent_node_t *xnode, *node, *prev, key; extent_node_t *xnode, *node, *prev, *xprev, key;
unzeroed = pages_purge(chunk, size); unzeroed = pages_purge(chunk, size);
VALGRIND_MAKE_MEM_NOACCESS(chunk, size); VALGRIND_MAKE_MEM_NOACCESS(chunk, size);
@ -226,6 +226,8 @@ chunk_record(extent_tree_t *chunks_szad, extent_tree_t *chunks_ad, void *chunk,
* held. * held.
*/ */
xnode = base_node_alloc(); xnode = base_node_alloc();
/* Use xprev to implement conditional deferred deallocation of prev. */
xprev = NULL;
malloc_mutex_lock(&chunks_mtx); malloc_mutex_lock(&chunks_mtx);
key.addr = (void *)((uintptr_t)chunk + size); key.addr = (void *)((uintptr_t)chunk + size);
@ -280,18 +282,19 @@ chunk_record(extent_tree_t *chunks_szad, extent_tree_t *chunks_ad, void *chunk,
node->zeroed = (node->zeroed && prev->zeroed); node->zeroed = (node->zeroed && prev->zeroed);
extent_tree_szad_insert(chunks_szad, node); extent_tree_szad_insert(chunks_szad, node);
base_node_dealloc(prev); xprev = prev;
} }
label_return: label_return:
malloc_mutex_unlock(&chunks_mtx); malloc_mutex_unlock(&chunks_mtx);
if (xnode != NULL) { /*
/* * Deallocate xnode and/or xprev after unlocking chunks_mtx in order to
* Deallocate xnode after unlocking chunks_mtx in order to * avoid potential deadlock.
* avoid potential deadlock. */
*/ if (xnode != NULL)
base_node_dealloc(xnode); base_node_dealloc(xnode);
} if (xprev != NULL)
base_node_dealloc(prev);
} }
void void