From: David Goulet Date: Tue, 25 Mar 2014 16:14:01 +0000 (-0400) Subject: Fix: don't set enabled flag is session start fails X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=a5a2d0c25460639304b9bd3991d874774553a39c;p=lttng-tools.git Fix: don't set enabled flag is session start fails The "started" var. is changed to the flag "has_been_started" indicating if at least ONE start command has been seen. The "enabled" var. is changed to the flag "active" and the semantic is the same. Backported from master. Signed-off-by: David Goulet Fixes #801 Conflicts: src/bin/lttng-sessiond/cmd.c --- diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c index c1f5a4e70..14390f3ec 100644 --- a/src/bin/lttng-sessiond/cmd.c +++ b/src/bin/lttng-sessiond/cmd.c @@ -850,6 +850,15 @@ int cmd_enable_channel(struct ltt_session *session, rcu_read_lock(); + /* + * Don't try to enable a channel if the session has been started at + * some point in time before. The tracer does not allow it. + */ + if (session->has_been_started) { + ret = LTTNG_ERR_TRACE_ALREADY_STARTED; + goto error; + } + /* * The ringbuffer (both in user space and kernel) behave badly in overwrite * mode and with less than 2 subbuf so block it right away and send back an @@ -868,15 +877,6 @@ int cmd_enable_channel(struct ltt_session *session, kchan = trace_kernel_get_channel_by_name(attr->name, session->kernel_session); if (kchan == NULL) { - /* - * Don't try to create a channel if the session - * has been started at some point in time - * before. The tracer does not allow it. - */ - if (session->started) { - ret = LTTNG_ERR_TRACE_ALREADY_STARTED; - goto error; - } ret = channel_kernel_create(session->kernel_session, attr, wpipe); if (attr->name[0] != '\0') { session->kernel_session->has_non_default_channel = 1; @@ -900,15 +900,6 @@ int cmd_enable_channel(struct ltt_session *session, uchan = trace_ust_find_channel_by_name(chan_ht, attr->name); if (uchan == NULL) { - /* - * Don't try to create a channel if the session - * has been started at some point in time - * before. The tracer does not allow it. - */ - if (session->started) { - ret = LTTNG_ERR_TRACE_ALREADY_STARTED; - goto error; - } ret = channel_ust_create(usess, attr, domain->buf_type); if (attr->name[0] != '\0') { usess->has_non_default_channel = 1; @@ -1603,8 +1594,8 @@ int cmd_start_trace(struct ltt_session *session) ksession = session->kernel_session; usess = session->ust_session; - if (session->enabled) { - /* Already started. */ + /* Is the session already started? */ + if (session->active) { ret = LTTNG_ERR_TRACE_ALREADY_STARTED; goto error; } @@ -1624,8 +1615,6 @@ int cmd_start_trace(struct ltt_session *session) goto error; } - session->enabled = 1; - /* Kernel tracing */ if (ksession != NULL) { ret = start_kernel_session(ksession, kernel_tracer_fd); @@ -1645,7 +1634,9 @@ int cmd_start_trace(struct ltt_session *session) } } - session->started = 1; + /* Flag this after a successful start. */ + session->has_been_started = 1; + session->active = 1; ret = LTTNG_OK; @@ -1669,13 +1660,12 @@ int cmd_stop_trace(struct ltt_session *session) ksession = session->kernel_session; usess = session->ust_session; - if (!session->enabled) { + /* Session is not active. Skip everythong and inform the client. */ + if (!session->active) { ret = LTTNG_ERR_TRACE_ALREADY_STOPPED; goto error; } - session->enabled = 0; - /* Kernel tracer */ if (ksession && ksession->started) { DBG("Stop kernel tracing"); @@ -1717,6 +1707,8 @@ int cmd_stop_trace(struct ltt_session *session) } } + /* Flag inactive after a successful stop. */ + session->active = 0; ret = LTTNG_OK; error: @@ -1738,8 +1730,8 @@ int cmd_set_consumer_uri(int domain, struct ltt_session *session, assert(uris); assert(nb_uri > 0); - /* Can't enable consumer after session started. */ - if (session->enabled) { + /* Can't set consumer URI if the session is active. */ + if (session->active) { ret = LTTNG_ERR_TRACE_ALREADY_STARTED; goto error; } @@ -2300,7 +2292,7 @@ void cmd_list_lttng_sessions(struct lttng_session *sessions, uid_t uid, strncpy(sessions[i].name, session->name, NAME_MAX); sessions[i].name[NAME_MAX - 1] = '\0'; - sessions[i].enabled = session->enabled; + sessions[i].enabled = session->active; sessions[i].snapshot_mode = session->snapshot_mode; i++; } @@ -2319,7 +2311,7 @@ int cmd_data_pending(struct ltt_session *session) assert(session); /* Session MUST be stopped to ask for data availability. */ - if (session->enabled) { + if (session->active) { ret = LTTNG_ERR_SESSION_STARTED; goto error; } else { @@ -2333,7 +2325,7 @@ int cmd_data_pending(struct ltt_session *session) * *VERY* important that we don't ask the consumer before a start * trace. */ - if (!session->started) { + if (!session->has_been_started) { ret = 0; goto error; } @@ -2765,7 +2757,7 @@ int cmd_snapshot_record(struct ltt_session *session, } /* The session needs to be started at least once. */ - if (!session->started) { + if (!session->has_been_started) { ret = LTTNG_ERR_START_SESSION_ONCE; goto error; } diff --git a/src/bin/lttng-sessiond/session.h b/src/bin/lttng-sessiond/session.h index 0fd2fb16a..f0e7bdb0e 100644 --- a/src/bin/lttng-sessiond/session.h +++ b/src/bin/lttng-sessiond/session.h @@ -68,7 +68,6 @@ struct ltt_session { */ pthread_mutex_t lock; struct cds_list_head list; - int enabled; /* enabled/started flag */ uint64_t id; /* session unique identifier */ /* UID/GID of the user owning the session */ uid_t uid; @@ -86,8 +85,13 @@ struct ltt_session { */ struct consumer_output *consumer; - /* Did a start command occured before the kern/ust session creation? */ - unsigned int started; + /* Did at least ONE start command has been triggered?. */ + unsigned int has_been_started:1; + /* + * Is the session active? Start trace command sets this to 1 and the stop + * command reset it to 0. + */ + unsigned int active:1; /* Snapshot representation in a session. */ struct snapshot snapshot;