Fix: consumer should await for initial streams

[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 11701aebfb9869b7e6dbac8deb26828bd3d8cebe..5a219fc0b6c543d5c0f5270c3febd4ccfb4adb3a 100644 (file)
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -118,7 +118,8 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
                                -1, -1,
                                msg.u.channel.mmap_len,
-                               msg.u.channel.max_sb_size);
+                               msg.u.channel.max_sb_size,
+                               msg.u.channel.nb_init_streams);
                if (new_channel == NULL) {
                        lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
                        goto end_nosignal;
@@ -295,7 +296,7 @@ end_nosignal:
 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                struct lttng_consumer_local_data *ctx)
 {
-       unsigned long len;
+       unsigned long len, subbuf_size, padding;
        int err;
        ssize_t ret = 0;
        int infd = stream->wait_fd;
@@ -304,6 +305,7 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
        /* Get the next subbuffer */
        err = kernctl_get_next_subbuf(infd);
        if (err != 0) {
+               ret = err;
                /*
                 * This is a debug message even for single-threaded consumer,
                 * because poll() have more relaxed criterions than get subbuf,
@@ -315,60 +317,92 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                goto end;
        }
 
+       /* Get the full subbuffer size including padding */
+       err = kernctl_get_padded_subbuf_size(infd, &len);
+       if (err != 0) {
+               errno = -err;
+               perror("Getting sub-buffer len failed.");
+               ret = err;
+               goto end;
+       }
+
        switch (stream->output) {
-               case LTTNG_EVENT_SPLICE:
-                       /* read the whole subbuffer */
-                       err = kernctl_get_padded_subbuf_size(infd, &len);
-                       if (err != 0) {
-                               errno = -ret;
-                               perror("Getting sub-buffer len failed.");
-                               goto end;
-                       }
+       case LTTNG_EVENT_SPLICE:
 
-                       /* splice the subbuffer to the tracefile */
-                       ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, len);
-                       if (ret != len) {
-                               /*
-                                * display the error but continue processing to try
-                                * to release the subbuffer
-                                */
-                               ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
-                                               ret, len);
-                       }
+               /*
+                * XXX: The lttng-modules splice "actor" does not handle copying
+                * partial pages hence only using the subbuffer size without the
+                * padding makes the splice fail.
+                */
+               subbuf_size = len;
+               padding = 0;
 
-                       break;
-               case LTTNG_EVENT_MMAP:
-                       /* read the used subbuffer size */
-                       err = kernctl_get_padded_subbuf_size(infd, &len);
-                       if (err != 0) {
-                               errno = -ret;
-                               perror("Getting sub-buffer len failed.");
-                               goto end;
-                       }
-                       /* write the subbuffer to the tracefile */
-                       ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
-                       if (ret != len) {
-                               /*
-                                * display the error but continue processing to try
-                                * to release the subbuffer
-                                */
-                               ERR("Error writing to tracefile");
-                       }
-                       break;
-               default:
-                       ERR("Unknown output method");
-                       ret = -1;
+               /* splice the subbuffer to the tracefile */
+               ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
+                               padding);
+               /*
+                * XXX: Splice does not support network streaming so the return value
+                * is simply checked against subbuf_size and not like the mmap() op.
+                */
+               if (ret != subbuf_size) {
+                       /*
+                        * display the error but continue processing to try
+                        * to release the subbuffer
+                        */
+                       ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
+                                       ret, subbuf_size);
+               }
+               break;
+       case LTTNG_EVENT_MMAP:
+               /* Get subbuffer size without padding */
+               err = kernctl_get_subbuf_size(infd, &subbuf_size);
+               if (err != 0) {
+                       errno = -err;
+                       perror("Getting sub-buffer len failed.");
+                       ret = err;
+                       goto end;
+               }
+
+               /* 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,
+                               padding);
+               /*
+                * The mmap operation should write subbuf_size amount of data when
+                * network streaming or the full padding (len) size when we are _not_
+                * streaming.
+                */
+               if ((ret != subbuf_size && stream->net_seq_idx != -1) ||
+                               (ret != len && stream->net_seq_idx == -1)) {
+                       /*
+                        * Display the error but continue processing to try to release the
+                        * subbuffer
+                        */
+                       ERR("Error writing to tracefile "
+                                       "(ret: %zd != len: %lu != subbuf_size: %lu)",
+                                       ret, len, subbuf_size);
+               }
+               break;
+       default:
+               ERR("Unknown output method");
+               ret = -1;
        }
 
        err = kernctl_put_next_subbuf(infd);
        if (err != 0) {
-               errno = -ret;
+               errno = -err;
                if (errno == EFAULT) {
                        perror("Error in unreserving sub buffer\n");
                } else if (errno == EIO) {
                        /* Should never happen with newer LTTng versions */
                        perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
                }
+
+               ret = -err;
                goto end;
        }