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Do not hold hash table lock while backtracing.

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There is a deadlock if holding the hash table lock while trying to do
a backtrace. Change the code so that the hash table lock is only held
while actually modifying either g_hash_table, or while modifying an
entry from g_hash_table.

Bug: 22423683
Change-Id: I604ea56f940f22e99da41ea4dcdf97bedaac268d
This commit is contained in:
Christopher Ferris 2015-07-11 22:47:06 -07:00
parent 65dd858239
commit 9fee99b060
1 changed files with 3 additions and 5 deletions
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8
libc/bionic/malloc_debug_leak.cpp
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@ -133,8 +133,9 @@ static HashEntry* record_backtrace(uintptr_t* backtrace, size_t numEntries, size
size |= SIZE_FLAG_ZYGOTE_CHILD;
}
// Keep the lock held for as little time as possible to prevent deadlocks.
ScopedPthreadMutexLocker locker(&g_hash_table->lock);
HashEntry* entry = find_entry(g_hash_table, slot, backtrace, numEntries, size);
if (entry != NULL) {
entry->allocations++;
} else {
@ -302,8 +303,6 @@ extern "C" void* leak_malloc(size_t bytes) {
void* base = g_malloc_dispatch->malloc(size);
if (base != NULL) {
ScopedPthreadMutexLocker locker(&g_hash_table->lock);
uintptr_t backtrace[BACKTRACE_SIZE];
size_t numEntries = GET_BACKTRACE(backtrace, BACKTRACE_SIZE);
@ -328,8 +327,6 @@ extern "C" void leak_free(void* mem) {
return;
}
ScopedPthreadMutexLocker locker(&g_hash_table->lock);
// check the guard to make sure it is valid
AllocationEntry* header = to_header(mem);
@ -342,6 +339,7 @@ extern "C" void leak_free(void* mem) {
}
}
ScopedPthreadMutexLocker locker(&g_hash_table->lock);
if (header->guard == GUARD || is_valid_entry(header->entry)) {
// decrement the allocations
HashEntry* entry = header->entry;