overlay: Constify perf ringbuffer

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/overlay/gpu-perf.c b/overlay/gpu-perf.c
index 7751132..4a3bc34 100644 (file)
--- a/overlay/gpu-perf.c
+++ b/overlay/gpu-perf.c
@@ -74,7 +74,7 @@ static uint64_t tracepoint_id(const char *sys, const char *name)
 
 static int perf_tracepoint_open(struct gpu_perf *gp,
                                const char *sys, const char *name,
-                               int (*func)(struct gpu_perf *, void *))
+                               int (*func)(struct gpu_perf *, const void *))
 {
        struct perf_event_attr attr;
        struct gpu_perf_sample *sample;
@@ -151,17 +151,17 @@ err:
        return EINVAL;
 }
 
-static int seqno_start(struct gpu_perf *gp, void *event)
+static int seqno_start(struct gpu_perf *gp, const void *event)
 {
        return 0;
 }
 
-static int seqno_end(struct gpu_perf *gp, void *event)
+static int seqno_end(struct gpu_perf *gp, const void *event)
 {
        return 0;
 }
 
-static int flip_complete(struct gpu_perf *gp, void *event)
+static int flip_complete(struct gpu_perf *gp, const void *event)
 {
        gp->flip_complete++;
        return 1;
@@ -186,9 +186,9 @@ void gpu_perf_init(struct gpu_perf *gp, unsigned flags)
 }
 
 static int process_sample(struct gpu_perf *gp,
-                         struct perf_event_header *header)
+                         const struct perf_event_header *header)
 {
-       struct sample_event *sample = (struct sample_event *)header;
+       const struct sample_event *sample = (const struct sample_event *)header;
        int n, update = 0;
 
        /* hash me! */
@@ -218,7 +218,7 @@ int gpu_perf_update(struct gpu_perf *gp)
 
        for (n = 0; n < gp->nr_cpus; n++) {
                struct perf_event_mmap_page *mmap = gp->map[n];
-               uint8_t *data;
+               const uint8_t *data;
                uint64_t head, tail;
 
                tail = mmap->data_tail;
@@ -230,14 +230,14 @@ int gpu_perf_update(struct gpu_perf *gp)
 
                data = (uint8_t *)mmap + gp->page_size;
                while (head - tail >= sizeof (struct perf_event_header)) {
-                       struct perf_event_header *header;
+                       const struct perf_event_header *header;
 
-                       header = (struct perf_event_header *)(data + (tail & mask));
+                       header = (const struct perf_event_header *)(data + (tail & mask));
                        if (header->size > head - tail)
                                break;
 
-                       if (data + (tail & mask) + header->size > data + size) {
-                               int before, after;
+                       if ((const uint8_t *)header + header->size > data + size) {
+                               int before;
 
                                if (header->size > buffer_size) {
                                        uint8_t *b = realloc(buffer, header->size);
@@ -248,11 +248,10 @@ int gpu_perf_update(struct gpu_perf *gp)
                                        buffer_size = header->size;
                                }
 
-                               after = (tail & mask) + header->size - size;
-                               before = header->size - after;
+                               before = data + size - (const uint8_t *)header;
 
-                               memcpy(buffer, data + (tail & mask), before);
-                               memcpy(buffer + before, data, after);
+                               memcpy(buffer, header, before);
+                               memcpy(buffer + before, data, header->size - before);
 
                                header = (struct perf_event_header *)buffer;
                        }

diff --git a/overlay/gpu-perf.h b/overlay/gpu-perf.h
index 58bf306..6a3e00d 100644 (file)
--- a/overlay/gpu-perf.h
+++ b/overlay/gpu-perf.h
@@ -8,7 +8,7 @@ struct gpu_perf {
        void **map;
        struct gpu_perf_sample {
                uint64_t id;
-               int (*func)(struct gpu_perf *, void *);
+               int (*func)(struct gpu_perf *, const void *);
        } *sample;
 
        int flip_complete;