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author | Tom Stellard <tstellar@redhat.com> | 2017-11-14 19:21:30 +0000 |
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committer | Tom Stellard <tstellar@redhat.com> | 2017-11-14 19:21:30 +0000 |
commit | b32afe4684b90410ba99850c9287e166f9615f1c (patch) | |
tree | 1384e63db0a438f7edfb260d1a996115b08446f7 | |
parent | def3a920c374b7c10623cda5de7c38e288878a5e (diff) | |
download | llvm-b32afe4684b90410ba99850c9287e166f9615f1c.zip llvm-b32afe4684b90410ba99850c9287e166f9615f1c.tar.gz llvm-b32afe4684b90410ba99850c9287e166f9615f1c.tar.bz2 |
Merging r317115:
------------------------------------------------------------------------
r317115 | jlpeyton | 2017-11-01 12:44:42 -0700 (Wed, 01 Nov 2017) | 19 lines
[OpenMP] Fix race condition in omp_init_lock
This is a partial fix for bug 34050.
This prevents callers of omp_set_lock (which does not hold __kmp_global_lock)
from ever seeing an uninitialized version of __kmp_i_lock_table.table.
It does not solve a use-after-free race condition if omp_set_lock obtains a
pointer to __kmp_i_lock_table.table before it is updated and then attempts to
dereference afterwards. That race is far less likely and can be handled in a
separate patch.
The unit test usually segfaults on the current trunk revision. It passes with
the patch.
Patch by Adam Azarchs
Differential Revision: https://reviews.llvm.org/D39439
------------------------------------------------------------------------
llvm-svn: 318178
-rw-r--r-- | openmp/runtime/src/kmp_lock.cpp | 7 | ||||
-rw-r--r-- | openmp/runtime/test/lock/omp_init_lock.c | 42 |
2 files changed, 46 insertions, 3 deletions
diff --git a/openmp/runtime/src/kmp_lock.cpp b/openmp/runtime/src/kmp_lock.cpp index e174981..ecdaca5 100644 --- a/openmp/runtime/src/kmp_lock.cpp +++ b/openmp/runtime/src/kmp_lock.cpp @@ -3061,11 +3061,12 @@ kmp_indirect_lock_t *__kmp_allocate_indirect_lock(void **user_lock, if (idx == __kmp_i_lock_table.size) { // Double up the space for block pointers int row = __kmp_i_lock_table.size / KMP_I_LOCK_CHUNK; - kmp_indirect_lock_t **old_table = __kmp_i_lock_table.table; - __kmp_i_lock_table.table = (kmp_indirect_lock_t **)__kmp_allocate( + kmp_indirect_lock_t **new_table = (kmp_indirect_lock_t **)__kmp_allocate( 2 * row * sizeof(kmp_indirect_lock_t *)); - KMP_MEMCPY(__kmp_i_lock_table.table, old_table, + KMP_MEMCPY(new_table, __kmp_i_lock_table.table, row * sizeof(kmp_indirect_lock_t *)); + kmp_indirect_lock_t **old_table = __kmp_i_lock_table.table; + __kmp_i_lock_table.table = new_table; __kmp_free(old_table); // Allocate new objects in the new blocks for (int i = row; i < 2 * row; ++i) diff --git a/openmp/runtime/test/lock/omp_init_lock.c b/openmp/runtime/test/lock/omp_init_lock.c new file mode 100644 index 0000000..24b60d1 --- /dev/null +++ b/openmp/runtime/test/lock/omp_init_lock.c @@ -0,0 +1,42 @@ +// RUN: %libomp-compile-and-run +#include "omp_testsuite.h" +#include <stdio.h> + +// This should be slightly less than KMP_I_LOCK_CHUNK, which is 1024 +#define LOCKS_PER_ITER 1000 +#define ITERATIONS (REPETITIONS + 1) + +// This tests concurrently using locks on one thread while initializing new +// ones on another thread. This exercises the global lock pool. +int test_omp_init_lock() { + int i; + omp_lock_t lcks[ITERATIONS * LOCKS_PER_ITER]; +#pragma omp parallel for schedule(static) num_threads(NUM_TASKS) + for (i = 0; i < ITERATIONS; i++) { + int j; + omp_lock_t *my_lcks = &lcks[i * LOCKS_PER_ITER]; + for (j = 0; j < LOCKS_PER_ITER; j++) { + omp_init_lock(&my_lcks[j]); + } + for (j = 0; j < LOCKS_PER_ITER * 100; j++) { + omp_set_lock(&my_lcks[j % LOCKS_PER_ITER]); + omp_unset_lock(&my_lcks[j % LOCKS_PER_ITER]); + } + } + // Wait until all repititions are done. The test is exercising growth of + // the global lock pool, which does not shrink when no locks are allocated. + { + int j; + for (j = 0; j < ITERATIONS * LOCKS_PER_ITER; j++) { + omp_destroy_lock(&lcks[j]); + } + } + + return 0; +} + +int main() { + // No use repeating this test, since it's exercising a private global pool + // which is not reset between test iterations. + return test_omp_init_lock(); +} |