Fix: remove padding field after variable sized array

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

diff --git a/libringbuffer/frontend_types.h b/libringbuffer/frontend_types.h
index 9c733d170fe7fadfb8fa8fe8a958bc7ef4de6d43..b6b34470ce28447b8f6dea168369078ec5a608ff 100644 (file)
--- a/libringbuffer/frontend_types.h
+++ b/libringbuffer/frontend_types.h
@@ -1,19 +1,31 @@
-#ifndef _LINUX_RING_BUFFER_FRONTEND_TYPES_H
-#define _LINUX_RING_BUFFER_FRONTEND_TYPES_H
+#ifndef _LTTNG_RING_BUFFER_FRONTEND_TYPES_H
+#define _LTTNG_RING_BUFFER_FRONTEND_TYPES_H
 
 /*
- * linux/ringbuffer/frontend_types.h
- *
- * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * libringbuffer/frontend_types.h
  *
  * Ring Buffer Library Synchronization Header (types).
  *
+ * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
  * Author:
  *     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  *
  * See ring_buffer_frontend.c for more information on wait-free algorithms.
- *
- * Dual LGPL v2.1/GPL v2 license.
  */
 
 #include <string.h>
@@ -21,10 +33,8 @@
 #include <urcu/list.h>
 #include <urcu/uatomic.h>
 
-#include "lttng/core.h"
-
-#include <lttng/usterr-signal-safe.h>
 #include <lttng/ringbuffer-config.h>
+#include <usterr-signal-safe.h>
 #include "backend_types.h"
 #include "shm_internal.h"
 #include "vatomic.h"
@@ -50,6 +60,7 @@ struct channel {
        //wait_queue_head_t read_wait;          /* reader wait queue */
        int finalized;                          /* Has channel been finalized */
        size_t priv_data_offset;
+       /* Note: padding field is missing */
        /*
         * Associated backend contains a variable-length array. Needs to
         * be last member.
@@ -58,17 +69,22 @@ struct channel {
 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
 
 /* Per-subbuffer commit counters used on the hot path */
+#define RB_COMMIT_COUNT_HOT_PADDING    16
 struct commit_counters_hot {
        union v_atomic cc;              /* Commit counter */
        union v_atomic seq;             /* Consecutive commits */
+       char padding[RB_COMMIT_COUNT_HOT_PADDING];
 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
 
 /* Per-subbuffer commit counters used only on cold paths */
+#define RB_COMMIT_COUNT_COLD_PADDING   24
 struct commit_counters_cold {
        union v_atomic cc_sb;           /* Incremented _once_ at sb switch */
+       char padding[RB_COMMIT_COUNT_COLD_PADDING];
 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
 
 /* ring buffer state */
+#define RB_RING_BUFFER_PADDING         64
 struct lttng_ust_lib_ring_buffer {
        /* First 32 bytes cache-hot cacheline */
        union v_atomic offset;          /* Current offset in the buffer */
@@ -106,11 +122,12 @@ struct lttng_ust_lib_ring_buffer {
        unsigned long get_subbuf_consumed;      /* Read-side consumed */
        unsigned long prod_snapshot;    /* Producer count snapshot */
        unsigned long cons_snapshot;    /* Consumer count snapshot */
-       int get_subbuf:1;               /* Sub-buffer being held by reader */
-       int switch_timer_enabled:1;     /* Protected by ring_buffer_nohz_lock */
-       int read_timer_enabled:1;       /* Protected by ring_buffer_nohz_lock */
+       unsigned int get_subbuf:1,      /* Sub-buffer being held by reader */
+               switch_timer_enabled:1, /* Protected by ring_buffer_nohz_lock */
+               read_timer_enabled:1;   /* Protected by ring_buffer_nohz_lock */
        /* shmp pointer to self */
        DECLARE_SHMP(struct lttng_ust_lib_ring_buffer, self);
+       char padding[RB_RING_BUFFER_PADDING];
 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
 
 static inline
@@ -119,6 +136,10 @@ void *channel_get_private(struct channel *chan)
        return ((char *) chan) + chan->priv_data_offset;
 }
 
+#ifndef __rb_same_type
+#define __rb_same_type(a, b)   __builtin_types_compatible_p(typeof(a), typeof(b))
+#endif
+
 /*
  * Issue warnings and disable channels upon internal error.
  * Can receive struct lttng_ust_lib_ring_buffer or struct lttng_ust_lib_ring_buffer_backend
@@ -129,11 +150,11 @@ void *channel_get_private(struct channel *chan)
                struct channel *__chan;                                 \
                int _____ret = caa_unlikely(cond);                              \
                if (_____ret) {                                         \
-                       if (__same_type(*(c), struct channel_backend))  \
+                       if (__rb_same_type(*(c), struct channel_backend))       \
                                __chan = caa_container_of((void *) (c), \
                                                        struct channel, \
                                                        backend);       \
-                       else if (__same_type(*(c), struct channel))     \
+                       else if (__rb_same_type(*(c), struct channel))  \
                                __chan = (void *) (c);                  \
                        else                                            \
                                BUG_ON(1);                              \
@@ -143,4 +164,4 @@ void *channel_get_private(struct channel *chan)
                _____ret;                                               \
        })
 
-#endif /* _LINUX_RING_BUFFER_FRONTEND_TYPES_H */
+#endif /* _LTTNG_RING_BUFFER_FRONTEND_TYPES_H */