Ok, first of all bind some buffers: pipe->set_vertex_buffers(pipe, 0, 1, &vtxbuf); pipe->set_vertex_buffers(pipe, 1, 1, &vtxbuf); pipe->set_vertex_buffers(pipe, 2, 1, &vtxbuf);
num_vtxbufs is now 3 as it should be. Now you are unbinding buffers, one after another starting at slot 0: pipe->set_vertex_buffers(pipe, 0, 1, NULL); enabled_buffers = (1ull << num_vtxbufs) - 1 = 0x7; util_set_vertex_buffers_mask(...); enabled_buffers = 0x6; num_vtxbufs = util_last_bit(enabled_buffers) = 3 pipe->set_vertex_buffers(pipe, 1, 1, NULL); enabled_buffers = (1ull << num_vtxbufs) - 1 = 0x7; util_set_vertex_buffers_mask(...); enabled_buffers = 0x5; num_vtxbufs = util_last_bit(enabled_buffers) = 3 pipe->set_vertex_buffers(pipe, 2, 1, NULL); enabled_buffers = (1ull << num_vtxbufs) - 1 = 0x7; util_set_vertex_buffers_mask(...); enabled_buffers = 0x3; num_vtxbufs = util_last_bit(enabled_buffers) = 2 There are no buffers bound any more, but num_vtxbufs is now 2 instead of 0. There would be no problem if you start at slot 2 going down to 0. There would be no problem if you unbind all buffers at once. I hope this clarifies the problem. Kind Regards, Patrick On 2015-12-09 07:10 PM, Ilia Mirkin wrote: > I'm probably just being dense... can you provide an exact sequence of > calls that would cause this logic to fail? Seems like it should work > as-is... > > On Sun, Dec 6, 2015 at 4:12 AM, Patrick Rudolph <s...@das-labor.org> wrote: >> In case a state tracker unbinds every slot by a seperate >> pipe->set_vertex_buffers() call, starting from slot zero, the number >> of bound buffers would not reach zero at all. Unbinding all buffers >> at once or starting at the top-most slot results in correct behaviour. >> >> Calculating the correct number of bound buffers fixes a NULL pointer >> dereference in nvc0_validate_vertex_buffers_shared(). >> >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93004 >> >> Signed-off-by: Patrick Rudolph <s...@das-labor.org> >> --- >> src/gallium/auxiliary/util/u_helpers.c | 8 +++++++- >> 1 file changed, 7 insertions(+), 1 deletion(-) >> >> diff --git a/src/gallium/auxiliary/util/u_helpers.c >> b/src/gallium/auxiliary/util/u_helpers.c >> index 09619c1..09020b0 100644 >> --- a/src/gallium/auxiliary/util/u_helpers.c >> +++ b/src/gallium/auxiliary/util/u_helpers.c >> @@ -81,7 +81,13 @@ void util_set_vertex_buffers_count(struct >> pipe_vertex_buffer *dst, >> const struct pipe_vertex_buffer *src, >> unsigned start_slot, unsigned count) >> { >> - uint32_t enabled_buffers = (1ull << *dst_count) - 1; >> + unsigned i; >> + uint32_t enabled_buffers = 0; >> + >> + for (i = 0; i < *dst_count; i++) { >> + if (dst[i].buffer || dst[i].user_buffer) >> + enabled_buffers |= (1ull << i); >> + } >> >> util_set_vertex_buffers_mask(dst, &enabled_buffers, src, start_slot, >> count); >> -- >> 2.4.3 >> >> _______________________________________________ >> mesa-dev mailing list >> mesa-dev@lists.freedesktop.org >> http://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
