Use shm handle, fix allocation space, take care of alignment

[lttng-ust.git] / libringbuffer / ring_buffer_backend.c

diff --git a/libringbuffer/ring_buffer_backend.c b/libringbuffer/ring_buffer_backend.c
index 8aa8c86fa7511a5d467815fa946f25277ceb87fc..797beb307e78d889dc8365cf05e018df0cfbd717 100644 (file)
--- a/libringbuffer/ring_buffer_backend.c
+++ b/libringbuffer/ring_buffer_backend.c
@@ -14,6 +14,7 @@
 #include "backend.h"
 #include "frontend.h"
 #include "smp.h"
+#include "shm.h"
 
 /**
  * lib_ring_buffer_backend_allocate - allocate a channel buffer
@@ -41,11 +42,18 @@ int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config *config
        if (extra_reader_sb)
                num_subbuf_alloc++;
 
+       /* Align the entire buffer backend data on PAGE_SIZE */
+       align_shm(shm_header, PAGE_SIZE);
        set_shmp(bufb->array, zalloc_shm(shm_header,
                        sizeof(*bufb->array) * num_subbuf_alloc));
        if (unlikely(!shmp(bufb->array)))
                goto array_error;
 
+       /*
+        * This is the largest element (the buffer pages) which needs to
+        * be aligned on PAGE_SIZE.
+        */
+       align_shm(shm_header, PAGE_SIZE);
        set_shmp(bufb->memory_map, zalloc_shm(shm_header,
                        subbuf_size * num_subbuf_alloc));
        if (unlikely(!shmp(bufb->memory_map)))
@@ -53,15 +61,16 @@ int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config *config
 
        /* Allocate backend pages array elements */
        for (i = 0; i < num_subbuf_alloc; i++) {
+               align_shm(shm_header, __alignof__(struct lib_ring_buffer_backend_pages));
                set_shmp(bufb->array[i],
                        zalloc_shm(shm_header,
-                               sizeof(struct lib_ring_buffer_backend_pages) +
-                               subbuf_size));
+                               sizeof(struct lib_ring_buffer_backend_pages)));
                if (!shmp(bufb->array[i]))
                        goto free_array;
        }
 
        /* Allocate write-side subbuffer table */
+       align_shm(shm_header, __alignof__(struct lib_ring_buffer_backend_subbuffer));
        bufb->buf_wsb = zalloc_shm(shm_header,
                                sizeof(struct lib_ring_buffer_backend_subbuffer)
                                * num_subbuf);
@@ -87,6 +96,12 @@ int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config *config
                        mmap_offset += subbuf_size;
                }
        }
+       /*
+        * Align the end of each buffer backend data on PAGE_SIZE, to
+        * behave like an array which contains elements that need to be
+        * aligned on PAGE_SIZE.
+        */
+       align_shm(shm_header, PAGE_SIZE);
 
        return 0;
 
@@ -235,6 +250,7 @@ int channel_backend_init(struct channel_backend *chanb,
                size_t alloc_size;
 
                /* Allocating the buffer per-cpu structures */
+               align_shm(shm_header, __alignof__(struct lib_ring_buffer));
                alloc_size = sizeof(struct lib_ring_buffer);
                buf = zalloc_shm(shm_header, alloc_size * num_possible_cpus());
                if (!buf)
@@ -254,8 +270,8 @@ int channel_backend_init(struct channel_backend *chanb,
                struct lib_ring_buffer *buf;
                size_t alloc_size;
 
+               align_shm(shm_header, __alignof__(struct lib_ring_buffer));
                alloc_size = sizeof(struct lib_ring_buffer);
-               chanb->buf = zmalloc(sizeof(struct lib_ring_buffer));
                buf = zalloc_shm(shm_header, alloc_size);
                if (!buf)
                        goto end;