radeonsi: prevent race conditions when doing scratch patching

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

diff --git a/src/gallium/drivers/radeonsi/si_state_shaders.c b/src/gallium/drivers/radeonsi/si_state_shaders.c
index 032cc0c3965aaeb28b06111130dfbced41672d3a..7da52f634565dcc0e524a9f83f7aa01a138de993 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_state_shaders.c
+++ b/src/gallium/drivers/radeonsi/si_state_shaders.c
@@ -2586,6 +2586,22 @@ static bool si_update_gs_ring_buffers(struct si_context *sctx)
        return true;
 }
 
+static void si_shader_lock(struct si_shader *shader)
+{
+       mtx_lock(&shader->selector->mutex);
+       if (shader->previous_stage_sel) {
+               assert(shader->previous_stage_sel != shader->selector);
+               mtx_lock(&shader->previous_stage_sel->mutex);
+       }
+}
+
+static void si_shader_unlock(struct si_shader *shader)
+{
+       if (shader->previous_stage_sel)
+               mtx_unlock(&shader->previous_stage_sel->mutex);
+       mtx_unlock(&shader->selector->mutex);
+}
+
 /**
  * @returns 1 if \p sel has been updated to use a new scratch buffer
  *          0 if not
@@ -2604,10 +2620,19 @@ static int si_update_scratch_buffer(struct si_context *sctx,
        if (shader->config.scratch_bytes_per_wave == 0)
                return 0;
 
+       /* Prevent race conditions when updating:
+        * - si_shader::scratch_bo
+        * - si_shader::binary::code
+        * - si_shader::previous_stage::binary::code.
+        */
+       si_shader_lock(shader);
+
        /* This shader is already configured to use the current
         * scratch buffer. */
-       if (shader->scratch_bo == sctx->scratch_buffer)
+       if (shader->scratch_bo == sctx->scratch_buffer) {
+               si_shader_unlock(shader);
                return 0;
+       }
 
        assert(sctx->scratch_buffer);
 
@@ -2618,14 +2643,17 @@ static int si_update_scratch_buffer(struct si_context *sctx,
 
        /* Replace the shader bo with a new bo that has the relocs applied. */
        r = si_shader_binary_upload(sctx->screen, shader);
-       if (r)
+       if (r) {
+               si_shader_unlock(shader);
                return r;
+       }
 
        /* Update the shader state to use the new shader bo. */
        si_shader_init_pm4_state(sctx->screen, shader);
 
        r600_resource_reference(&shader->scratch_bo, sctx->scratch_buffer);
 
+       si_shader_unlock(shader);
        return 1;
 }