freedreno: Take a lock around shader variant creation.

Shaders are shared across contexts in gallium (part of making it so
that you get shader compile at link time, for shader-db and to reduce
compiles at draw time).  So, we need to protect from variant creation
for a shader from multiple threads at the same time.

Reviewed-by: Rob Clark <robdclark@gmail.com>

src/freedreno/ir3/ir3_shader.c

@@ -239,6 +239,7 @@ struct ir3_shader_variant *
 ir3_shader_get_variant(struct ir3_shader *shader, struct ir3_shader_key *key,
 		bool binning_pass, bool *created)
 {
+	mtx_lock(&shader->variants_lock);
 	struct ir3_shader_variant *v =
 			shader_variant(shader, key, created);
 
@@ -247,8 +248,10 @@ ir3_shader_get_variant(struct ir3_shader *shader, struct ir3_shader_key *key,
 			v->binning = create_variant(shader, key, true);
 			*created = true;
 		}
+		mtx_unlock(&shader->variants_lock);
 		return v->binning;
 	}
+	mtx_unlock(&shader->variants_lock);
 
 	return v;
 }
@@ -264,6 +267,7 @@ ir3_shader_destroy(struct ir3_shader *shader)
 	}
 	free(shader->const_state.immediates);
 	ralloc_free(shader->nir);
+	mtx_destroy(&shader->variants_lock);
 	free(shader);
 }
 
@@ -272,6 +276,7 @@ ir3_shader_from_nir(struct ir3_compiler *compiler, nir_shader *nir)
 {
 	struct ir3_shader *shader = CALLOC_STRUCT(ir3_shader);
 
+	mtx_init(&shader->variants_lock, mtx_plain);
 	shader->compiler = compiler;
 	shader->id = ++shader->compiler->shader_count;
 	shader->type = nir->info.stage;

src/freedreno/ir3/ir3_shader.h

@@ -29,6 +29,7 @@
 
 #include <stdio.h>
 
+#include "c11/threads.h"
 #include "compiler/shader_enums.h"
 #include "compiler/nir/nir.h"
 #include "util/bitscan.h"
@@ -544,6 +545,7 @@ struct ir3_shader {
 	struct ir3_stream_output_info stream_output;
 
 	struct ir3_shader_variant *variants;
+	mtx_t variants_lock;
 };
 
 void * ir3_shader_assemble(struct ir3_shader_variant *v, uint32_t gpu_id);