X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=lttng-events.c;h=8befa34f7ad6f4d5dc7d676adf4b40709d5ef814;hb=de9b16cda94d0e1cab5f9980f2a699e2b2fb93a1;hp=2820a0e4d1f9045017dd772d08b7f9325be85cc9;hpb=165eee701dce7f180d958125c1794459280fe64d;p=lttng-modules.git diff --git a/lttng-events.c b/lttng-events.c index 2820a0e4..8befa34f 100644 --- a/lttng-events.c +++ b/lttng-events.c @@ -34,6 +34,8 @@ #include #include #include +#include + #include "wrapper/uuid.h" #include "wrapper/vmalloc.h" /* for wrapper_vmalloc_sync_all() */ #include "wrapper/random.h" @@ -42,6 +44,9 @@ #include "lttng-events.h" #include "lttng-tracer.h" #include "lttng-abi-old.h" +#include "wrapper/vzalloc.h" +#include "wrapper/ringbuffer/backend.h" +#include "wrapper/ringbuffer/frontend.h" #define METADATA_CACHE_DEFAULT_SIZE 4096 @@ -96,12 +101,12 @@ struct lttng_session *lttng_session_create(void) GFP_KERNEL); if (!metadata_cache) goto err_free_session; - metadata_cache->data = kzalloc(METADATA_CACHE_DEFAULT_SIZE, - GFP_KERNEL); + metadata_cache->data = lttng_vzalloc(METADATA_CACHE_DEFAULT_SIZE); if (!metadata_cache->data) goto err_free_cache; metadata_cache->cache_alloc = METADATA_CACHE_DEFAULT_SIZE; kref_init(&metadata_cache->refcount); + mutex_init(&metadata_cache->lock); session->metadata_cache = metadata_cache; INIT_LIST_HEAD(&metadata_cache->metadata_stream); memcpy(&metadata_cache->uuid, &session->uuid, @@ -123,7 +128,7 @@ void metadata_cache_destroy(struct kref *kref) { struct lttng_metadata_cache *cache = container_of(kref, struct lttng_metadata_cache, refcount); - kfree(cache->data); + vfree(cache->data); kfree(cache); } @@ -183,6 +188,12 @@ int lttng_session_enable(struct lttng_session *session) chan->header_type = 2; /* large */ } + /* Clear each stream's quiescent state. */ + list_for_each_entry(chan, &session->chan, list) { + if (chan->channel_type != METADATA_CHANNEL) + lib_ring_buffer_clear_quiescent_channel(chan->chan); + } + ACCESS_ONCE(session->active) = 1; ACCESS_ONCE(session->been_active) = 1; ret = _lttng_session_metadata_statedump(session); @@ -201,6 +212,7 @@ end: int lttng_session_disable(struct lttng_session *session) { int ret = 0; + struct lttng_channel *chan; mutex_lock(&sessions_mutex); if (!session->active) { @@ -208,6 +220,13 @@ int lttng_session_disable(struct lttng_session *session) goto end; } ACCESS_ONCE(session->active) = 0; + + /* Set each stream's quiescent state. */ + list_for_each_entry(chan, &session->chan, list) { + if (chan->channel_type != METADATA_CHANNEL) + lib_ring_buffer_set_quiescent_channel(chan->chan); + } + end: mutex_unlock(&sessions_mutex); return ret; @@ -595,10 +614,12 @@ void _lttng_event_destroy(struct lttng_event *event) /* * Serialize at most one packet worth of metadata into a metadata * channel. - * We have exclusive access to our metadata buffer (protected by the - * sessions_mutex), so we can do racy operations such as looking for - * remaining space left in packet and write, since mutual exclusion - * protects us from concurrent writes. + * We grab the metadata cache mutex to get exclusive access to our metadata + * buffer and to the metadata cache. Exclusive access to the metadata buffer + * allows us to do racy operations such as looking for remaining space left in + * packet and write, since mutual exclusion protects us from concurrent writes. + * Mutual exclusion on the metadata cache allow us to read the cache content + * without racing against reallocation of the cache by updates. * Returns the number of bytes written in the channel, 0 if no data * was written and a negative value on error. */ @@ -610,13 +631,15 @@ int lttng_metadata_output_channel(struct lttng_metadata_stream *stream, size_t len, reserve_len; /* - * Ensure we support mutiple get_next / put sequences followed - * by put_next. The metadata stream lock internally protects - * reading the metadata cache. It can indeed be read - * concurrently by "get_next_subbuf" and "flush" operations on - * the buffer invoked by different processes. + * Ensure we support mutiple get_next / put sequences followed by + * put_next. The metadata cache lock protects reading the metadata + * cache. It can indeed be read concurrently by "get_next_subbuf" and + * "flush" operations on the buffer invoked by different processes. + * Moreover, since the metadata cache memory can be reallocated, we + * need to have exclusive access against updates even though we only + * read it. */ - mutex_lock(&stream->lock); + mutex_lock(&stream->metadata_cache->lock); WARN_ON(stream->metadata_in < stream->metadata_out); if (stream->metadata_in != stream->metadata_out) goto end; @@ -646,13 +669,15 @@ int lttng_metadata_output_channel(struct lttng_metadata_stream *stream, ret = reserve_len; end: - mutex_unlock(&stream->lock); + mutex_unlock(&stream->metadata_cache->lock); return ret; } /* * Write the metadata to the metadata cache. * Must be called with sessions_mutex held. + * The metadata cache lock protects us from concurrent read access from + * thread outputting metadata content to ring buffer. */ int lttng_metadata_printf(struct lttng_session *session, const char *fmt, ...) @@ -671,6 +696,7 @@ int lttng_metadata_printf(struct lttng_session *session, return -ENOMEM; len = strlen(str); + mutex_lock(&session->metadata_cache->lock); if (session->metadata_cache->metadata_written + len > session->metadata_cache->cache_alloc) { char *tmp_cache_realloc; @@ -679,10 +705,16 @@ int lttng_metadata_printf(struct lttng_session *session, tmp_cache_alloc_size = max_t(unsigned int, session->metadata_cache->cache_alloc + len, session->metadata_cache->cache_alloc << 1); - tmp_cache_realloc = krealloc(session->metadata_cache->data, - tmp_cache_alloc_size, GFP_KERNEL); + tmp_cache_realloc = lttng_vzalloc(tmp_cache_alloc_size); if (!tmp_cache_realloc) goto err; + if (session->metadata_cache->data) { + memcpy(tmp_cache_realloc, + session->metadata_cache->data, + session->metadata_cache->cache_alloc); + vfree(session->metadata_cache->data); + } + session->metadata_cache->cache_alloc = tmp_cache_alloc_size; session->metadata_cache->data = tmp_cache_realloc; } @@ -690,6 +722,7 @@ int lttng_metadata_printf(struct lttng_session *session, session->metadata_cache->metadata_written, str, len); session->metadata_cache->metadata_written += len; + mutex_unlock(&session->metadata_cache->lock); kfree(str); list_for_each_entry(stream, &session->metadata_cache->metadata_stream, list) @@ -698,6 +731,7 @@ int lttng_metadata_printf(struct lttng_session *session, return 0; err: + mutex_unlock(&session->metadata_cache->lock); kfree(str); return -ENOMEM; }