Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756317Ab3JKAvA (ORCPT ); Thu, 10 Oct 2013 20:51:00 -0400 Received: from mga11.intel.com ([192.55.52.93]:32156 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755822Ab3JKAss (ORCPT ); Thu, 10 Oct 2013 20:48:48 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.90,1075,1371106800"; d="scan'208";a="415183136" From: Tom Zanussi To: rostedt@goodmis.org Cc: masami.hiramatsu.pt@hitachi.com, linux-kernel@vger.kernel.org, Tom Zanussi Subject: [PATCH v10 04/12] tracing: Add 'snapshot' event trigger command Date: Thu, 10 Oct 2013 19:48:28 -0500 Message-Id: <4ed13a4c303b83164992b92dc17d79717bea2116.1381445299.git.tom.zanussi@linux.intel.com> X-Mailer: git-send-email 1.7.11.4 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7243 Lines: 239 Add 'snapshot' event_command. snapshot event triggers are added by the user via this command in a similar way and using practically the same syntax as the analogous 'snapshot' ftrace function command, but instead of writing to the set_ftrace_filter file, the snapshot event trigger is written to the per-event 'trigger' files: echo 'snapshot' > .../somesys/someevent/trigger The above command will turn on snapshots for someevent i.e. whenever someevent is hit, a snapshot will be done. This also adds a 'count' version that limits the number of times the command will be invoked: echo 'snapshot:N' > .../somesys/someevent/trigger Where N is the number of times the command will be invoked. The above command will snapshot N times for someevent i.e. whenever someevent is hit N times, a snapshot will be done. Also adds a new tracing_alloc_snapshot() function - the existing tracing_snapshot_alloc() function is a special version of tracing_snapshot() that also does the snapshot allocation - the snapshot triggers would like to be able to do just the allocation but not take a snapshot; the existing tracing_snapshot_alloc() in turn now also calls tracing_alloc_snapshot() underneath to do that allocation. Signed-off-by: Tom Zanussi --- include/linux/ftrace_event.h | 1 + include/linux/kernel.h | 2 + kernel/trace/trace.c | 33 ++++++++++++-- kernel/trace/trace_events_trigger.c | 85 +++++++++++++++++++++++++++++++++++++ 4 files changed, 118 insertions(+), 3 deletions(-) diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index a14650b..40b517b 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -319,6 +319,7 @@ struct ftrace_event_file { enum event_trigger_type { ETT_NONE = (0), ETT_TRACE_ONOFF = (1 << 0), + ETT_SNAPSHOT = (1 << 1), }; extern void destroy_preds(struct ftrace_event_call *call); diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 672ddc4..51d6e90 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -497,6 +497,7 @@ void tracing_on(void); void tracing_off(void); int tracing_is_on(void); void tracing_snapshot(void); +int tracing_alloc_snapshot(void); void tracing_snapshot_alloc(void); extern void tracing_start(void); @@ -646,6 +647,7 @@ static inline void tracing_on(void) { } static inline void tracing_off(void) { } static inline int tracing_is_on(void) { return 0; } static inline void tracing_snapshot(void) { } +static inline int tracing_alloc_snapshot(void) { return -ENODEV; } static inline void tracing_snapshot_alloc(void) { } static inline __printf(1, 2) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 7974ba2..5e41e6d0 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -575,6 +575,28 @@ void free_snapshot(struct trace_array *tr) } /** + * tracing_alloc_snapshot - allocate snapshot buffer. + * + * This only allocates the snapshot buffer if it isn't already + * allocated - it doesn't also take a snapshot. + * + * This is meant to be used in cases where the snapshot buffer needs + * to be set up for events that can't sleep but need to be able to + * trigger a snapshot. + */ +int tracing_alloc_snapshot(void) +{ + struct trace_array *tr = &global_trace; + int ret; + + ret = alloc_snapshot(tr); + WARN_ON(ret < 0); + + return ret; +} +EXPORT_SYMBOL_GPL(tracing_alloc_snapshot); + +/** * trace_snapshot_alloc - allocate and take a snapshot of the current buffer. * * This is similar to trace_snapshot(), but it will allocate the @@ -587,11 +609,10 @@ void free_snapshot(struct trace_array *tr) */ void tracing_snapshot_alloc(void) { - struct trace_array *tr = &global_trace; int ret; - ret = alloc_snapshot(tr); - if (WARN_ON(ret < 0)) + ret = tracing_alloc_snapshot(); + if (ret < 0) return; tracing_snapshot(); @@ -603,6 +624,12 @@ void tracing_snapshot(void) WARN_ONCE(1, "Snapshot feature not enabled, but internal snapshot used"); } EXPORT_SYMBOL_GPL(tracing_snapshot); +int tracing_alloc_snapshot(void) +{ + WARN_ONCE(1, "Snapshot feature not enabled, but snapshot allocation used"); + return -ENODEV; +} +EXPORT_SYMBOL_GPL(tracing_alloc_snapshot); void tracing_snapshot_alloc(void) { /* Give warning */ diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c index 4ea72ee..d775c3d 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -696,6 +696,90 @@ static struct event_command trigger_traceoff_cmd = { .get_trigger_ops = onoff_get_trigger_ops, }; +#ifdef CONFIG_TRACER_SNAPSHOT +static void +snapshot_trigger(struct event_trigger_data *data) +{ + tracing_snapshot(); +} + +static void +snapshot_count_trigger(struct event_trigger_data *data) +{ + if (!data->count) + return; + + if (data->count != -1) + (data->count)--; + + snapshot_trigger(data); +} + +static int +register_snapshot_trigger(char *glob, struct event_trigger_ops *ops, + struct event_trigger_data *data, + struct ftrace_event_file *file) +{ + int ret = register_trigger(glob, ops, data, file); + + if (ret > 0 && tracing_alloc_snapshot() != 0) { + unregister_trigger(glob, ops, data, file); + ret = 0; + } + + return ret; +} + +static int +snapshot_trigger_print(struct seq_file *m, struct event_trigger_ops *ops, + struct event_trigger_data *data) +{ + return event_trigger_print("snapshot", m, (void *)data->count, + data->filter_str); +} + +static struct event_trigger_ops snapshot_trigger_ops = { + .func = snapshot_trigger, + .print = snapshot_trigger_print, + .init = event_trigger_init, + .free = event_trigger_free, +}; + +static struct event_trigger_ops snapshot_count_trigger_ops = { + .func = snapshot_count_trigger, + .print = snapshot_trigger_print, + .init = event_trigger_init, + .free = event_trigger_free, +}; + +static struct event_trigger_ops * +snapshot_get_trigger_ops(char *cmd, char *param) +{ + return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops; +} + +static struct event_command trigger_snapshot_cmd = { + .name = "snapshot", + .trigger_type = ETT_SNAPSHOT, + .func = event_trigger_callback, + .reg = register_snapshot_trigger, + .unreg = unregister_trigger, + .get_trigger_ops = snapshot_get_trigger_ops, +}; + +static __init int register_trigger_snapshot_cmd(void) +{ + int ret; + + ret = register_event_command(&trigger_snapshot_cmd); + WARN_ON(ret < 0); + + return ret; +} +#else +static __init int register_trigger_snapshot_cmd(void) { return 0; } +#endif /* CONFIG_TRACER_SNAPSHOT */ + static __init void unregister_trigger_traceon_traceoff_cmds(void) { unregister_event_command(&trigger_traceon_cmd); @@ -719,6 +803,7 @@ static __init int register_trigger_traceon_traceoff_cmds(void) __init int register_trigger_cmds(void) { register_trigger_traceon_traceoff_cmds(); + register_trigger_snapshot_cmd(); return 0; } -- 1.7.11.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/