consumerd: move address computation from on_read_subbuffer_mmap

[lttng-tools.git] / src / common / kernel-consumer / kernel-consumer.c

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index c5c87cc9e12ff191337c2e40283ca7a860193a26..275c963df2305dee886327378f0a6a78e977e8db 100644 (file)
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -1,22 +1,13 @@
 /*
- * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
- *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (C) 2017 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ * Copyright (C) 2011 Julien Desfossez <julien.desfossez@polymtl.ca>
+ * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License, version 2 only,
- * as published by the Free Software Foundation.
+ * SPDX-License-Identifier: GPL-2.0-only
  *
- * This program 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 General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#include <stdint.h>
 #define _LGPL_SOURCE
 #include <assert.h>
 #include <poll.h>
@@ -123,6 +114,25 @@ int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
        return ret;
 }
 
+static
+int get_current_subbuf_addr(struct lttng_consumer_stream *stream,
+               const char **addr)
+{
+       int ret;
+       unsigned long mmap_offset;
+       const char *mmap_base = stream->mmap_base;
+
+       ret = kernctl_get_mmap_read_offset(stream->wait_fd, &mmap_offset);
+       if (ret < 0) {
+               PERROR("Failed to get mmap read offset");
+               goto error;
+       }
+
+       *addr = mmap_base + mmap_offset;
+error:
+       return ret;
+}
+
 /*
  * Take a snapshot of all the stream of a channel
  * RCU read-side lock must be held across this function to ensure existence of
@@ -238,6 +248,7 @@ static int lttng_kconsumer_snapshot_channel(
                while ((long) (consumed_pos - produced_pos) < 0) {
                        ssize_t read_len;
                        unsigned long len, padded_len;
+                       const char *subbuf_addr;
 
                        health_code_update();
 
@@ -267,7 +278,13 @@ static int lttng_kconsumer_snapshot_channel(
                                goto error_put_subbuf;
                        }
 
-                       read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
+                       ret = get_current_subbuf_addr(stream, &subbuf_addr);
+                       if (ret) {
+                               goto error_put_subbuf;
+                       }
+
+                       read_len = lttng_consumer_on_read_subbuffer_mmap(ctx,
+                                       stream, subbuf_addr, len,
                                        padded_len - len, NULL);
                        /*
                         * We write the padded len in local tracefiles but the data len
@@ -1701,6 +1718,9 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                }
                break;
        case CONSUMER_CHANNEL_MMAP:
+       {
+               const char *subbuf_addr;
+
                /* Get subbuffer size without padding */
                err = kernctl_get_subbuf_size(infd, &subbuf_size);
                if (err != 0) {
@@ -1720,13 +1740,20 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                        goto error;
                }
 
+               ret = get_current_subbuf_addr(stream, &subbuf_addr);
+               if (ret) {
+                       goto error_put_subbuf;
+               }
+
                /* Make sure the tracer is not gone mad on us! */
                assert(len >= subbuf_size);
 
                padding = len - subbuf_size;
 
                /* write the subbuffer to the tracefile */
-               ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
+               ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream,
+                               subbuf_addr,
+                               subbuf_size,
                                padding, &index);
                /*
                 * The mmap operation should write subbuf_size amount of data when
@@ -1746,11 +1773,12 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                        write_index = 0;
                }
                break;
+       }
        default:
                ERR("Unknown output method");
                ret = -EPERM;
        }
-
+error_put_subbuf:
        err = kernctl_put_next_subbuf(infd);
        if (err != 0) {
                if (err == -EFAULT) {