On 04/12/2020 11:27, Chris Wilson wrote:
Race the execution and interrupt handlers along a context, while
closing it at a random time.
v2: Some comments to handwave away the knowledge of internal
implementation details.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
tests/i915/gem_ctx_exec.c | 84 +++++++++++++++++++++++++++++++++++++++
1 file changed, 84 insertions(+)
diff --git a/tests/i915/gem_ctx_exec.c b/tests/i915/gem_ctx_exec.c
index 194191def..5c6109237 100644
--- a/tests/i915/gem_ctx_exec.c
+++ b/tests/i915/gem_ctx_exec.c
@@ -43,6 +43,7 @@
#include "i915/gem.h"
#include "igt.h"
#include "igt_dummyload.h"
+#include "igt_rand.h"
#include "igt_sysfs.h"
#include "sw_sync.h"
@@ -336,6 +337,86 @@ static void nohangcheck_hostile(int i915)
close(i915);
}
+static void close_race(int i915)
+{
+ const int ncpus = sysconf(_SC_NPROCESSORS_ONLN);
+ uint32_t *contexts;
+
+ contexts = mmap(NULL, 4096, PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
+ igt_assert(contexts != MAP_FAILED);
+
+ for (int child = 0; child < ncpus; child++)
+ contexts[child] = gem_context_clone_with_engines(i915, 0);
+
+ igt_fork(child, ncpus) {
+ igt_spin_t *spin;
+
+ spin = igt_spin_new(i915, .flags = IGT_SPIN_POLL_RUN);
+ igt_spin_end(spin);
+ gem_sync(i915, spin->handle);
+
+ while (!READ_ONCE(contexts[ncpus])) {
+ int64_t timeout = 1;
+
+ igt_spin_reset(spin);
+ igt_assert(!igt_spin_has_started(spin));
+
+ spin->execbuf.rsvd1 = READ_ONCE(contexts[child]);
+ if (__gem_execbuf(i915, &spin->execbuf))
+ continue;
+
+ /*
+ * One race we are particularly interested in is the
+ * handling of interrupt signaling along a closed
+ * context. We want to see if we can catch the kernel
+ * freeing the context while using it in the interrupt
+ * handler.
+ *
+ * There's no API to mandate that the interrupt is
+ * generate for a wait, nor that the implementation
+ * details of the kernel will not change to remove
+ * context access during interrupt processing. But
+ * for now, this should be interesting.
+ *
+ * Even if the signaling implementation is changed,
+ * racing context closure versus execbuf and looking
+ * at the outcome is very useful.
+ */
+
+ igt_assert(gem_bo_busy(i915, spin->handle));
+ gem_wait(i915, spin->handle, &timeout); /* prime irq */
+ igt_spin_busywait_until_started(spin);
+
+ igt_spin_end(spin);
+ gem_sync(i915, spin->handle);
+ }
+
+ igt_spin_free(i915, spin);
+ }
+
+ igt_until_timeout(5) {
+ /*
+ * Recreate all the contexts while they are in active use
+ * by the children. This may race with any of their ioctls
+ * and the kernel's context/request handling.
+ */
+ for (int child = 0; child < ncpus; child++) {
+ gem_context_destroy(i915, contexts[child]);
+ contexts[child] =
+ gem_context_clone_with_engines(i915, 0);
+ }
+ usleep(1000 + hars_petruska_f54_1_random_unsafe() % 2000);
+ }
+
+ contexts[ncpus] = 1;
+ igt_waitchildren();
+
+ for (int child = 0; child < ncpus; child++)
+ gem_context_destroy(i915, contexts[child]);
+
+ munmap(contexts, 4096);
+}
+
igt_main
{
const uint32_t batch[2] = { 0, MI_BATCH_BUFFER_END };
@@ -380,6 +461,9 @@ igt_main
igt_subtest("basic-nohangcheck")
nohangcheck_hostile(fd);
+ igt_subtest("basic-close-race")
+ close_race(fd);
+
igt_subtest("reset-pin-leak") {
int i;
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Regards,
Tvrtko
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