[PATCH] drm/amd/ras: Reduce stack usage in amdgpu_virt_ras_get_cper_records()

[Srinivasan Shanmugam]

amdgpu_virt_ras_get_cper_records() was using a large stack array
of ras_log_info pointers. This contributed to the frame size
warning on this function.

Replace the fixed-size stack array:

    struct ras_log_info *trace[MAX_RECORD_PER_BATCH];

with a heap-allocated array using kcalloc().

We free the trace buffer together with out_buf on all exit paths.
If allocation of trace or out_buf fails, we return a generic RAS
error code.

This reduces stack usage and keeps the runtime behaviour
unchanged.

Fixes:
stack frame size: 1112 bytes (limit: 1024)

Cc: Tao Zhou <tao.zh...@amd.com>
Cc: Hawking Zhang <hawking.zh...@amd.com>
Cc: Christian König <christian.koe...@amd.com>
Cc: Alex Deucher <alexander.deuc...@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmu...@amd.com>
---
 .../drm/amd/ras/ras_mgr/amdgpu_virt_ras_cmd.c   | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/ras/ras_mgr/amdgpu_virt_ras_cmd.c 
b/drivers/gpu/drm/amd/ras/ras_mgr/amdgpu_virt_ras_cmd.c
index 5e90a187155b..a75479593864 100644
--- a/drivers/gpu/drm/amd/ras/ras_mgr/amdgpu_virt_ras_cmd.c
+++ b/drivers/gpu/drm/amd/ras/ras_mgr/amdgpu_virt_ras_cmd.c
@@ -183,7 +183,7 @@ static int amdgpu_virt_ras_get_cper_records(struct 
ras_core_context *ras_core,
                (struct ras_cmd_cper_record_rsp *)cmd->output_buff_raw;
        struct ras_log_batch_overview *overview = 
&virt_ras->batch_mgr.batch_overview;
        struct ras_cmd_batch_trace_record_rsp *rsp_cache = 
&virt_ras->batch_mgr.batch_trace;
-       struct ras_log_info *trace[MAX_RECORD_PER_BATCH] = {0};
+       struct ras_log_info **trace;
        uint32_t offset = 0, real_data_len = 0;
        uint64_t batch_id;
        uint8_t *out_buf;
@@ -195,9 +195,15 @@ static int amdgpu_virt_ras_get_cper_records(struct 
ras_core_context *ras_core,
        if (!req->buf_size || !req->buf_ptr || !req->cper_num)
                return RAS_CMD__ERROR_INVALID_INPUT_DATA;
 
+       trace = kcalloc(MAX_RECORD_PER_BATCH, sizeof(*trace), GFP_KERNEL);
+       if (!trace)
+               return RAS_CMD__ERROR_GENERIC;
+
        out_buf = kzalloc(req->buf_size, GFP_KERNEL);
-       if (!out_buf)
+       if (!out_buf) {
+               kfree(trace);
                return RAS_CMD__ERROR_GENERIC;
+       }
 
        memset(out_buf, 0, req->buf_size);
 
@@ -205,8 +211,9 @@ static int amdgpu_virt_ras_get_cper_records(struct 
ras_core_context *ras_core,
                batch_id = req->cper_start_id + i;
                if (batch_id >= overview->last_batch_id)
                        break;
-               count = amdgpu_virt_ras_get_batch_records(ras_core, batch_id, 
trace,
-                                       ARRAY_SIZE(trace), rsp_cache);
+               count = amdgpu_virt_ras_get_batch_records(ras_core, batch_id,
+                                                         trace, 
MAX_RECORD_PER_BATCH,
+                                                         rsp_cache);
                if (count > 0) {
                        ret = ras_cper_generate_cper(ras_core, trace, count,
                                        &out_buf[offset], req->buf_size - 
offset, &real_data_len);
@@ -220,6 +227,7 @@ static int amdgpu_virt_ras_get_cper_records(struct 
ras_core_context *ras_core,
        if ((ret && (ret != -ENOMEM)) ||
            copy_to_user(u64_to_user_ptr(req->buf_ptr), out_buf, offset)) {
                kfree(out_buf);
+               kfree(trace);
                return RAS_CMD__ERROR_GENERIC;
        }
 
@@ -231,6 +239,7 @@ static int amdgpu_virt_ras_get_cper_records(struct 
ras_core_context *ras_core,
        cmd->output_size = sizeof(struct ras_cmd_cper_record_rsp);
 
        kfree(out_buf);
+       kfree(trace);
 
        return RAS_CMD__SUCCESS;
 }
-- 
2.34.1