Ring buffer: use shmp (shared-memory pointers) for per-channel shm structures

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

diff --git a/libringbuffer/backend.h b/libringbuffer/backend.h
index 61d2f3277f3192765b14b51f8175d40e1b8a8d42..1bd61109ca0096e2685b864324449b5760dc3128 100644 (file)
--- a/libringbuffer/backend.h
+++ b/libringbuffer/backend.h
@@ -32,10 +32,6 @@ extern size_t lib_ring_buffer_read(struct lib_ring_buffer_backend *bufb,
 extern int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb,
                                     size_t offset, void *dest, size_t len);
 
-extern struct page **
-lib_ring_buffer_read_get_page(struct lib_ring_buffer_backend *bufb, size_t offset,
-                             void ***virt);
-
 /*
  * Return the address where a given offset is located.
  * Should be used to get the current subbuffer header pointer. Given we know
@@ -68,29 +64,27 @@ void lib_ring_buffer_write(const struct lib_ring_buffer_config *config,
 {
        struct lib_ring_buffer_backend *bufb = &ctx->buf->backend;
        struct channel_backend *chanb = &ctx->chan->backend;
-       size_t sbidx, index;
+       size_t sbidx;
        size_t offset = ctx->buf_offset;
-       ssize_t pagecpy;
        struct lib_ring_buffer_backend_pages *rpages;
        unsigned long sb_bindex, id;
 
        offset &= chanb->buf_size - 1;
        sbidx = offset >> chanb->subbuf_size_order;
-       index = (offset & (chanb->subbuf_size - 1)) >> get_count_order(PAGE_SIZE);
-       pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK);
-       id = bufb->buf_wsb[sbidx].id;
+       id = shmp(bufb->buf_wsb)[sbidx].id;
        sb_bindex = subbuffer_id_get_index(config, id);
-       rpages = bufb->array[sb_bindex];
+       rpages = shmp(bufb->array)[sb_bindex];
        CHAN_WARN_ON(ctx->chan,
                     config->mode == RING_BUFFER_OVERWRITE
                     && subbuffer_id_is_noref(config, id));
-       if (likely(pagecpy == len))
-               lib_ring_buffer_do_copy(config,
-                                       rpages->p[index].virt
-                                           + (offset & ~PAGE_MASK),
-                                       src, len);
-       else
-               _lib_ring_buffer_write(bufb, offset, src, len, 0);
+       /*
+        * Underlying layer should never ask for writes across
+        * subbuffers.
+        */
+       CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
+       lib_ring_buffer_do_copy(config,
+                               shmp(rpages->p) + (offset & ~(chanb->subbuf_size - 1)),
+                               src, len);
        ctx->buf_offset += len;
 }
 
@@ -109,16 +103,16 @@ unsigned long lib_ring_buffer_get_records_unread(
        unsigned long records_unread = 0, sb_bindex, id;
        unsigned int i;
 
-       for (i = 0; i < bufb->chan->backend.num_subbuf; i++) {
-               id = bufb->buf_wsb[i].id;
+       for (i = 0; i < shmp(bufb->chan)->backend.num_subbuf; i++) {
+               id = shmp(bufb->buf_wsb)[i].id;
                sb_bindex = subbuffer_id_get_index(config, id);
-               pages = bufb->array[sb_bindex];
+               pages = shmp(bufb->array)[sb_bindex];
                records_unread += v_read(config, &pages->records_unread);
        }
        if (config->mode == RING_BUFFER_OVERWRITE) {
                id = bufb->buf_rsb.id;
                sb_bindex = subbuffer_id_get_index(config, id);
-               pages = bufb->array[sb_bindex];
+               pages = shmp(bufb->array)[sb_bindex];
                records_unread += v_read(config, &pages->records_unread);
        }
        return records_unread;