From 4caf3f8b94a38e738314f484d18b531dfa16ff8a Mon Sep 17 00:00:00 2001 From: Sverker Eriksson Date: Mon, 15 Apr 2013 14:07:42 +0200 Subject: erts: Fix locking order violation for allocation wrappers Some query functions in erl_alloc_util.c lock the allocator mutex and then use erts_printf that in turn may call the sys allocator through the wrappers. To avoid breaking locking order these query functions first "pre-locks" all allocator wrappers. --- erts/emulator/beam/erl_alloc.c | 51 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) (limited to 'erts/emulator/beam/erl_alloc.c') diff --git a/erts/emulator/beam/erl_alloc.c b/erts/emulator/beam/erl_alloc.c index f0cc52e30f..c19a2647e4 100644 --- a/erts/emulator/beam/erl_alloc.c +++ b/erts/emulator/beam/erl_alloc.c @@ -570,6 +570,8 @@ erts_alloc_init(int *argc, char **argv, ErtsAllocInitOpts *eaiop) if (ncpu < 1) ncpu = 1; + erts_tsd_key_create(&erts_allctr_prelock_tsd_key); + erts_sys_alloc_init(); erts_init_utils_mem(); @@ -3139,6 +3141,55 @@ erts_request_alloc_info(struct process *c_p, return 1; } +/* + * The allocator wrapper prelocking stuff below is about the locking order. + * It only affects wrappers (erl_mtrace.c and erl_instrument.c) that keep locks + * during alloc/realloc/free. + * + * Some query functions in erl_alloc_util.c lock the allocator mutex and then + * use erts_printf that in turn may call the sys allocator through the wrappers. + * To avoid breaking locking order these query functions first "pre-locks" all + * allocator wrappers. + */ +ErtsAllocatorWrapper_t *erts_allctr_wrappers; +int erts_allctr_wrapper_prelocked = 0; +erts_tsd_key_t erts_allctr_prelock_tsd_key; + +void erts_allctr_wrapper_prelock_init(ErtsAllocatorWrapper_t* wrapper) +{ + ASSERT(wrapper->lock && wrapper->unlock); + wrapper->next = erts_allctr_wrappers; + erts_allctr_wrappers = wrapper; +} + +void erts_allctr_wrapper_pre_lock(void) +{ + if (erts_allctr_wrappers) { + ErtsAllocatorWrapper_t* wrapper = erts_allctr_wrappers; + for ( ; wrapper; wrapper = wrapper->next) { + wrapper->lock(); + } + ASSERT(!erts_allctr_wrapper_prelocked); + erts_allctr_wrapper_prelocked = 1; + erts_tsd_set(erts_allctr_prelock_tsd_key, (void*)1); + } +} + +void erts_allctr_wrapper_pre_unlock(void) +{ + if (erts_allctr_wrappers) { + ErtsAllocatorWrapper_t* wrapper = erts_allctr_wrappers; + + erts_allctr_wrapper_prelocked = 0; + erts_tsd_set(erts_allctr_prelock_tsd_key, (void*)0); + for ( ; wrapper; wrapper = wrapper->next) { + wrapper->unlock(); + } + } +} + + + /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\ * Deprecated functions * * * -- cgit v1.2.3