| Message ID | 20200211192253.1120964-1-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [i-g-t] i915/gem_ctx_persistence: Race context closure with replace-engines | expand |
On 11/02/2020 19:22, Chris Wilson wrote: > Tvrtko spotted a race condition between replacing a set of hanging > engines and closing the context. So exercise it. > > 5s is not much time to hit the small window, but a little bit of testing > several times a day is better than nothing. > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> > --- > tests/i915/gem_ctx_persistence.c | 93 ++++++++++++++++++++++++++++++++ > 1 file changed, 93 insertions(+) > > diff --git a/tests/i915/gem_ctx_persistence.c b/tests/i915/gem_ctx_persistence.c > index 22f29d25e..6321dbe67 100644 > --- a/tests/i915/gem_ctx_persistence.c > +++ b/tests/i915/gem_ctx_persistence.c > @@ -33,6 +33,7 @@ > #include "i915/gem_engine_topology.h" > #include "i915/gem_ring.h" > #include "i915/gem_submission.h" > +#include "igt_aux.h" > #include "igt_debugfs.h" > #include "igt_dummyload.h" > #include "igt_gt.h" > @@ -803,6 +804,95 @@ static void replace_engines(int i915, const struct intel_execution_engine2 *e) > gem_quiescent_gpu(i915); > } > > +struct close_race { > + int pipe[2]; > +}; > + > +static void race_set_engines(int i915, int fd) > +{ > + I915_DEFINE_CONTEXT_PARAM_ENGINES(engines, 1) = { > + .engines = {} > + }; > + struct drm_i915_gem_context_param param = { > + .param = I915_CONTEXT_PARAM_ENGINES, > + .value = to_user_pointer(&engines), > + .size = sizeof(engines), > + }; > + > + while (read(fd, ¶m.ctx_id, sizeof(param.ctx_id)) > 0) { > + if (!param.ctx_id) > + break; > + __gem_context_set_param(i915, ¶m); > + } > +} > + > +static void close_replace_race(int i915) > +{ > + const int ncpus = sysconf(_SC_NPROCESSORS_ONLN); > + struct close_race *t; > + int fence = -1; > + > + /* > + * Tvrtko being the evil genius noticed that if we could successfully > + * replace a set of engines after the context had been closed, those > + * engines could escape oversight. > + */ I think it would read better if you reworded this a bit not to mention names and claimed attributes. :) > + > + t = malloc(sizeof(*t) * ncpus); > + igt_assert(t); > + > + for (int i = 0; i < ncpus; i++) > + igt_assert(pipe(t[i].pipe) == 0); > + > + igt_fork(child, ncpus) { > + close(t[child].pipe[1]); > + race_set_engines(i915, t[child].pipe[0]); > + } > + > + for (int i = 0; i < ncpus; i++) > + close(t[i].pipe[0]); > + > + igt_until_timeout(5) { > + igt_spin_t *spin; > + uint32_t ctx; > + > + ctx = gem_context_clone_with_engines(i915, 0); > + gem_context_set_persistence(i915, ctx, true); > + > + spin = igt_spin_new(i915, ctx, .flags = IGT_SPIN_FENCE_OUT); > + for (int i = 0; i < ncpus; i++) > + write(t[i].pipe[1], &ctx, sizeof(ctx)); It's early so I hope I am not too confused, but drm client in the forked process is a different one. So I think it needs to use threads to be able to share. Regards, Tvrtko > + > + if (fence < 0) { > + fence = spin->out_fence; > + } else { > + int tmp; > + > + tmp = sync_fence_merge(fence, spin->out_fence); > + close(fence); > + close(spin->out_fence); > + > + fence = tmp; > + } > + spin->out_fence = -1; > + > + gem_context_destroy(i915, ctx); > + } > + > + for (int i = 0; i < ncpus; i++) { > + uint32_t end = 0; > + write(t[i].pipe[1], &end, sizeof(end)); > + close(t[i].pipe[1]); > + } > + igt_waitchildren(); > + free(t); > + > + igt_assert(sync_fence_wait(fence, MSEC_PER_SEC / 2) == 0); > + close(fence); > + > + gem_quiescent_gpu(i915); > +} > + > static void replace_engines_hostile(int i915, > const struct intel_execution_engine2 *e) > { > @@ -961,6 +1051,9 @@ igt_main > replace_engines_hostile(i915, e); > } > } > + > + igt_subtest("close-replace-race") > + close_replace_race(i915); > } > > igt_fixture { >
Quoting Tvrtko Ursulin (2020-02-13 09:07:59) > > On 11/02/2020 19:22, Chris Wilson wrote: > > + igt_until_timeout(5) { > > + igt_spin_t *spin; > > + uint32_t ctx; > > + > > + ctx = gem_context_clone_with_engines(i915, 0); > > + gem_context_set_persistence(i915, ctx, true); > > + > > + spin = igt_spin_new(i915, ctx, .flags = IGT_SPIN_FENCE_OUT); > > + for (int i = 0; i < ncpus; i++) > > + write(t[i].pipe[1], &ctx, sizeof(ctx)); > > It's early so I hope I am not too confused, but drm client in the forked > process is a different one. So I think it needs to use threads to be > able to share. It using the same fd, so the children have control over the parents ctx (and shares the ctx id space via the fd) -Chris
On 13/02/2020 09:51, Chris Wilson wrote: > Quoting Tvrtko Ursulin (2020-02-13 09:07:59) >> >> On 11/02/2020 19:22, Chris Wilson wrote: >>> + igt_until_timeout(5) { >>> + igt_spin_t *spin; >>> + uint32_t ctx; >>> + >>> + ctx = gem_context_clone_with_engines(i915, 0); >>> + gem_context_set_persistence(i915, ctx, true); >>> + >>> + spin = igt_spin_new(i915, ctx, .flags = IGT_SPIN_FENCE_OUT); >>> + for (int i = 0; i < ncpus; i++) >>> + write(t[i].pipe[1], &ctx, sizeof(ctx)); >> >> It's early so I hope I am not too confused, but drm client in the forked >> process is a different one. So I think it needs to use threads to be >> able to share. > > It using the same fd, so the children have control over the parents ctx > (and shares the ctx id space via the fd) It was too early then. Then with a more neutral comment: Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Regards, Tvrtko
diff --git a/tests/i915/gem_ctx_persistence.c b/tests/i915/gem_ctx_persistence.c index 22f29d25e..6321dbe67 100644 --- a/tests/i915/gem_ctx_persistence.c +++ b/tests/i915/gem_ctx_persistence.c @@ -33,6 +33,7 @@ #include "i915/gem_engine_topology.h" #include "i915/gem_ring.h" #include "i915/gem_submission.h" +#include "igt_aux.h" #include "igt_debugfs.h" #include "igt_dummyload.h" #include "igt_gt.h" @@ -803,6 +804,95 @@ static void replace_engines(int i915, const struct intel_execution_engine2 *e) gem_quiescent_gpu(i915); } +struct close_race { + int pipe[2]; +}; + +static void race_set_engines(int i915, int fd) +{ + I915_DEFINE_CONTEXT_PARAM_ENGINES(engines, 1) = { + .engines = {} + }; + struct drm_i915_gem_context_param param = { + .param = I915_CONTEXT_PARAM_ENGINES, + .value = to_user_pointer(&engines), + .size = sizeof(engines), + }; + + while (read(fd, ¶m.ctx_id, sizeof(param.ctx_id)) > 0) { + if (!param.ctx_id) + break; + __gem_context_set_param(i915, ¶m); + } +} + +static void close_replace_race(int i915) +{ + const int ncpus = sysconf(_SC_NPROCESSORS_ONLN); + struct close_race *t; + int fence = -1; + + /* + * Tvrtko being the evil genius noticed that if we could successfully + * replace a set of engines after the context had been closed, those + * engines could escape oversight. + */ + + t = malloc(sizeof(*t) * ncpus); + igt_assert(t); + + for (int i = 0; i < ncpus; i++) + igt_assert(pipe(t[i].pipe) == 0); + + igt_fork(child, ncpus) { + close(t[child].pipe[1]); + race_set_engines(i915, t[child].pipe[0]); + } + + for (int i = 0; i < ncpus; i++) + close(t[i].pipe[0]); + + igt_until_timeout(5) { + igt_spin_t *spin; + uint32_t ctx; + + ctx = gem_context_clone_with_engines(i915, 0); + gem_context_set_persistence(i915, ctx, true); + + spin = igt_spin_new(i915, ctx, .flags = IGT_SPIN_FENCE_OUT); + for (int i = 0; i < ncpus; i++) + write(t[i].pipe[1], &ctx, sizeof(ctx)); + + if (fence < 0) { + fence = spin->out_fence; + } else { + int tmp; + + tmp = sync_fence_merge(fence, spin->out_fence); + close(fence); + close(spin->out_fence); + + fence = tmp; + } + spin->out_fence = -1; + + gem_context_destroy(i915, ctx); + } + + for (int i = 0; i < ncpus; i++) { + uint32_t end = 0; + write(t[i].pipe[1], &end, sizeof(end)); + close(t[i].pipe[1]); + } + igt_waitchildren(); + free(t); + + igt_assert(sync_fence_wait(fence, MSEC_PER_SEC / 2) == 0); + close(fence); + + gem_quiescent_gpu(i915); +} + static void replace_engines_hostile(int i915, const struct intel_execution_engine2 *e) { @@ -961,6 +1051,9 @@ igt_main replace_engines_hostile(i915, e); } } + + igt_subtest("close-replace-race") + close_replace_race(i915); } igt_fixture {
Tvrtko spotted a race condition between replacing a set of hanging engines and closing the context. So exercise it. 5s is not much time to hit the small window, but a little bit of testing several times a day is better than nothing. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> --- tests/i915/gem_ctx_persistence.c | 93 ++++++++++++++++++++++++++++++++ 1 file changed, 93 insertions(+)