From: Markus Elfring <elfr...@users.sourceforge.net>
Date: Tue, 26 Dec 2023 18:22:54 +0100

Memory releases were triggered during error handling only over
the label “fail”.

1. Return directly after a call of the function “kcalloc” failed
   at the beginning.

2. Reduce the data processing at the end to a required kfree() call order
   also by adjusting jump targets.

3. Delete an initialisation for the variable “validated_shader”
   which became unnecessary with this refactoring.

Signed-off-by: Markus Elfring <elfr...@users.sourceforge.net>
---
 drivers/gpu/drm/vc4/vc4_validate_shaders.c | 42 +++++++++++-----------
 1 file changed, 21 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_validate_shaders.c 
b/drivers/gpu/drm/vc4/vc4_validate_shaders.c
index 9745f8810eca..d76787bb7d51 100644
--- a/drivers/gpu/drm/vc4/vc4_validate_shaders.c
+++ b/drivers/gpu/drm/vc4/vc4_validate_shaders.c
@@ -783,7 +783,7 @@ vc4_validate_shader(struct drm_gem_dma_object *shader_obj)
        int shader_end_ip = 0;
        uint32_t last_thread_switch_ip = -3;
        uint32_t ip;
-       struct vc4_validated_shader_info *validated_shader = NULL;
+       struct vc4_validated_shader_info *validated_shader;
        struct vc4_shader_validation_state validation_state;

        if (WARN_ON_ONCE(vc4->is_vc5))
@@ -799,14 +799,14 @@ vc4_validate_shader(struct drm_gem_dma_object *shader_obj)
                kcalloc(BITS_TO_LONGS(validation_state.max_ip),
                        sizeof(unsigned long), GFP_KERNEL);
        if (!validation_state.branch_targets)
-               goto fail;
+               return NULL;

        validated_shader = kcalloc(1, sizeof(*validated_shader), GFP_KERNEL);
        if (!validated_shader)
-               goto fail;
+               goto free_targets;

        if (!vc4_validate_branches(&validation_state))
-               goto fail;
+               goto free_shader;

        for (ip = 0; ip < validation_state.max_ip; ip++) {
                uint64_t inst = validation_state.shader[ip];
@@ -815,7 +815,7 @@ vc4_validate_shader(struct drm_gem_dma_object *shader_obj)
                validation_state.ip = ip;

                if (!vc4_handle_branch_target(&validation_state))
-                       goto fail;
+                       goto free_offsets;

                if (ip == last_thread_switch_ip + 3) {
                        /* Reset r0-r3 live clamp data */
@@ -842,12 +842,12 @@ vc4_validate_shader(struct drm_gem_dma_object *shader_obj)
                        if (!check_instruction_writes(validated_shader,
                                                      &validation_state)) {
                                DRM_DEBUG("Bad write at ip %d\n", ip);
-                               goto fail;
+                               goto free_offsets;
                        }

                        if (!check_instruction_reads(validated_shader,
                                                     &validation_state))
-                               goto fail;
+                               goto free_offsets;

                        if (sig == QPU_SIG_PROG_END) {
                                found_shader_end = true;
@@ -861,7 +861,7 @@ vc4_validate_shader(struct drm_gem_dma_object *shader_obj)
                                if (ip < last_thread_switch_ip + 3) {
                                        DRM_DEBUG("Thread switch too soon after 
"
                                                  "last switch at ip %d\n", ip);
-                                       goto fail;
+                                       goto free_offsets;
                                }
                                last_thread_switch_ip = ip;
                        }
@@ -872,26 +872,26 @@ vc4_validate_shader(struct drm_gem_dma_object *shader_obj)
                        if (!check_instruction_writes(validated_shader,
                                                      &validation_state)) {
                                DRM_DEBUG("Bad LOAD_IMM write at ip %d\n", ip);
-                               goto fail;
+                               goto free_offsets;
                        }
                        break;

                case QPU_SIG_BRANCH:
                        if (!check_branch(inst, validated_shader,
                                          &validation_state, ip))
-                               goto fail;
+                               goto free_offsets;

                        if (ip < last_thread_switch_ip + 3) {
                                DRM_DEBUG("Branch in thread switch at ip %d",
                                          ip);
-                               goto fail;
+                               goto free_offsets;
                        }

                        break;
                default:
                        DRM_DEBUG("Unsupported QPU signal %d at "
                                  "instruction %d\n", sig, ip);
-                       goto fail;
+                       goto free_offsets;
                }

                /* There are two delay slots after program end is signaled
@@ -905,7 +905,7 @@ vc4_validate_shader(struct drm_gem_dma_object *shader_obj)
                DRM_DEBUG("shader failed to terminate before "
                          "shader BO end at %zd\n",
                          shader_obj->base.size);
-               goto fail;
+               goto free_offsets;
        }

        /* Might corrupt other thread */
@@ -913,7 +913,7 @@ vc4_validate_shader(struct drm_gem_dma_object *shader_obj)
            validation_state.all_registers_used) {
                DRM_DEBUG("Shader uses threading, but uses the upper "
                          "half of the registers, too\n");
-               goto fail;
+               goto free_offsets;
        }

        /* If we did a backwards branch and we haven't emitted a uniforms
@@ -927,7 +927,7 @@ vc4_validate_shader(struct drm_gem_dma_object *shader_obj)
         */
        if (validation_state.needs_uniform_address_for_loop) {
                if (!require_uniform_address_uniform(validated_shader))
-                       goto fail;
+                       goto free_offsets;
                validated_shader->uniforms_size += 4;
        }

@@ -943,12 +943,12 @@ vc4_validate_shader(struct drm_gem_dma_object *shader_obj)

        return validated_shader;

-fail:
+free_offsets:
+       kfree(validated_shader->uniform_addr_offsets);
+       kfree(validated_shader->texture_samples);
+free_shader:
+       kfree(validated_shader);
+free_targets:
        kfree(validation_state.branch_targets);
-       if (validated_shader) {
-               kfree(validated_shader->uniform_addr_offsets);
-               kfree(validated_shader->texture_samples);
-               kfree(validated_shader);
-       }
        return NULL;
 }
--
2.43.0

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