Fix: remove padding field after variable sized array
[lttng-ust.git] / libringbuffer / frontend_types.h
index 974f782e0dc86b3ed3903ec861ede6754504fbd9..b6b34470ce28447b8f6dea168369078ec5a608ff 100644 (file)
@@ -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>
 #include <urcu/list.h>
 #include <urcu/uatomic.h>
 
-#include "ust/core.h"
-
-#include <ust/usterr-signal-safe.h>
-#include <ust/ringbuffer-config.h>
+#include <lttng/ringbuffer-config.h>
+#include <usterr-signal-safe.h>
 #include "backend_types.h"
 #include "shm_internal.h"
+#include "vatomic.h"
 
 /*
  * A switch is done during tracing or as a final flush after tracing (so it
@@ -44,27 +55,37 @@ struct channel {
                                                 * subbuffer index.
                                                 */
 
-       struct channel_backend backend;         /* Associated backend */
-
        unsigned long switch_timer_interval;    /* Buffer flush (jiffies) */
        unsigned long read_timer_interval;      /* Reader wakeup (jiffies) */
        //wait_queue_head_t read_wait;          /* reader wait queue */
        int finalized;                          /* Has channel been finalized */
-} ____cacheline_aligned;
+       size_t priv_data_offset;
+       /* Note: padding field is missing */
+       /*
+        * Associated backend contains a variable-length array. Needs to
+        * be last member.
+        */
+       struct channel_backend backend;         /* Associated backend */
+} __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 */
-} ____cacheline_aligned;
+       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 */
-} ____cacheline_aligned;
+       char padding[RB_COMMIT_COUNT_COLD_PADDING];
+} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
 
 /* ring buffer state */
-struct lib_ring_buffer {
+#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 */
        DECLARE_SHMP(struct commit_counters_hot, commit_hot);
@@ -79,7 +100,7 @@ struct lib_ring_buffer {
                                         * Last timestamp written in the buffer.
                                         */
 
-       struct lib_ring_buffer_backend backend; /* Associated backend */
+       struct lttng_ust_lib_ring_buffer_backend backend;       /* Associated backend */
 
        DECLARE_SHMP(struct commit_counters_cold, commit_cold);
                                        /* Commit count per sub-buffer */
@@ -87,6 +108,7 @@ struct lib_ring_buffer {
                                         * Active readers count
                                         * standard atomic access (shared)
                                         */
+       long active_shadow_readers;
                                        /* Dropped records */
        union v_atomic records_lost_full;       /* Buffer full */
        union v_atomic records_lost_wrap;       /* Nested wrap-around */
@@ -100,32 +122,39 @@ struct 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 */
-} ____cacheline_aligned;
+       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
 void *channel_get_private(struct channel *chan)
 {
-       return chan->backend.priv;
+       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 lib_ring_buffer or struct lib_ring_buffer_backend
+ * Can receive struct lttng_ust_lib_ring_buffer or struct lttng_ust_lib_ring_buffer_backend
  * parameters.
  */
 #define CHAN_WARN_ON(c, cond)                                          \
        ({                                                              \
                struct channel *__chan;                                 \
-               int _____ret = unlikely(cond);                          \
+               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);                              \
@@ -135,4 +164,4 @@ void *channel_get_private(struct channel *chan)
                _____ret;                                               \
        })
 
-#endif /* _LINUX_RING_BUFFER_FRONTEND_TYPES_H */
+#endif /* _LTTNG_RING_BUFFER_FRONTEND_TYPES_H */
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