ring buffer: handle shmp errors

[lttng-ust.git] / libringbuffer / backend.h

diff --git a/libringbuffer/backend.h b/libringbuffer/backend.h
index 53a97140bf33bfd70c21f6b7939c1f48251cb20f..2dec003883c7536ce3912b94b4a9987cc5d3b777 100644 (file)
--- a/libringbuffer/backend.h
+++ b/libringbuffer/backend.h
@@ -83,6 +83,8 @@ void lib_ring_buffer_write(const struct lttng_ust_lib_ring_buffer_config *config
        size_t offset = ctx->buf_offset;
        struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
        unsigned long sb_bindex, id;
+       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+       void *p;
 
        if (caa_unlikely(!len))
                return;
@@ -91,6 +93,8 @@ void lib_ring_buffer_write(const struct lttng_ust_lib_ring_buffer_config *config
        id = shmp_index(handle, bufb->buf_wsb, sbidx)->id;
        sb_bindex = subbuffer_id_get_index(config, id);
        rpages = shmp_index(handle, bufb->array, sb_bindex);
+       if (caa_unlikely(!rpages))
+               return;
        CHAN_WARN_ON(ctx->chan,
                     config->mode == RING_BUFFER_OVERWRITE
                     && subbuffer_id_is_noref(config, id));
@@ -99,9 +103,13 @@ void lib_ring_buffer_write(const struct lttng_ust_lib_ring_buffer_config *config
         * subbuffers.
         */
        CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
-       lib_ring_buffer_do_copy(config,
-                               shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1)),
-                               src, len);
+       backend_pages = shmp(handle, rpages->shmp);
+       if (caa_unlikely(!backend_pages))
+               return;
+       p = shmp_index(handle, backend_pages->p, offset & (chanb->subbuf_size - 1));
+       if (caa_unlikely(!p))
+               return;
+       lib_ring_buffer_do_copy(config, p, src, len);
        ctx->buf_offset += len;
 }
 
@@ -207,21 +215,42 @@ unsigned long lib_ring_buffer_get_records_unread(
                                struct lttng_ust_shm_handle *handle)
 {
        struct lttng_ust_lib_ring_buffer_backend *bufb = &buf->backend;
-       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages;
-       unsigned long records_unread = 0, sb_bindex, id;
+       unsigned long records_unread = 0, sb_bindex;
        unsigned int i;
+       struct channel *chan;
 
-       for (i = 0; i < shmp(handle, bufb->chan)->backend.num_subbuf; i++) {
-               id = shmp_index(handle, bufb->buf_wsb, i)->id;
-               sb_bindex = subbuffer_id_get_index(config, id);
-               pages = shmp_index(handle, bufb->array, sb_bindex);
-               records_unread += v_read(config, &shmp(handle, pages->shmp)->records_unread);
+       chan = shmp(handle, bufb->chan);
+       if (!chan)
+               return 0;
+       for (i = 0; i < chan->backend.num_subbuf; i++) {
+               struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
+               struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
+               struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+
+               wsb = shmp_index(handle, bufb->buf_wsb, i);
+               if (!wsb)
+                       return 0;
+               sb_bindex = subbuffer_id_get_index(config, wsb->id);
+               rpages = shmp_index(handle, bufb->array, sb_bindex);
+               if (!rpages)
+                       return 0;
+               backend_pages = shmp(handle, rpages->shmp);
+               if (!backend_pages)
+                       return 0;
+               records_unread += v_read(config, &backend_pages->records_unread);
        }
        if (config->mode == RING_BUFFER_OVERWRITE) {
-               id = bufb->buf_rsb.id;
-               sb_bindex = subbuffer_id_get_index(config, id);
-               pages = shmp_index(handle, bufb->array, sb_bindex);
-               records_unread += v_read(config, &shmp(handle, pages->shmp)->records_unread);
+               struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
+               struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+
+               sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id);
+               rpages = shmp_index(handle, bufb->array, sb_bindex);
+               if (!rpages)
+                       return 0;
+               backend_pages = shmp(handle, rpages->shmp);
+               if (!backend_pages)
+                       return 0;
+               records_unread += v_read(config, &backend_pages->records_unread);
        }
        return records_unread;
 }