From 83e99914c9e2677d8a80f2a23eca0d215d5bfb0f Mon Sep 17 00:00:00 2001 From: Tom Zanussi Date: Thu, 3 Mar 2016 12:54:46 -0600 Subject: [PATCH] tracing: Add hist trigger support for pausing and continuing a trace Allow users to append 'pause' or 'continue' to an existing trigger in order to have it paused or to have a paused trace continue. This expands the hist trigger syntax from this: # echo hist:keys=xxx:vals=yyy:sort=zzz.descending \ [ if filter] >> event/trigger to this: # echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause or cont \ [ if filter] >> event/trigger Link: http://lkml.kernel.org/r/b672a92c14702cb924cdf6fc27ea1809bed04907.1457029949.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi Tested-by: Masami Hiramatsu Reviewed-by: Namhyung Kim Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 7 ++++++- kernel/trace/trace_events_hist.c | 31 ++++++++++++++++++++++++++++--- 2 files changed, 34 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d16fa8e1cdbf..7d5c63dd410a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3837,6 +3837,7 @@ static const char readme_msg[] = "\t [:values=]\n" "\t [:sort=]\n" "\t [:size=#entries]\n" + "\t [:pause][:continue]\n" "\t [if ]\n\n" "\t When a matching event is hit, an entry is added to a hash\n" "\t table using the key(s) and value(s) named, and the value of a\n" @@ -3851,7 +3852,11 @@ static const char readme_msg[] = "\t used to specify more or fewer than the default 2048 entries\n" "\t for the hashtable size.\n\n" "\t Reading the 'hist' file for the event will dump the hash\n" - "\t table in its entirety to stdout." + "\t table in its entirety to stdout.\n\n" + "\t The 'pause' parameter can be used to pause an existing hist\n" + "\t trigger or to start a hist trigger but not log any events\n" + "\t until told to do so. 'continue' can be used to start or\n" + "\t restart a paused hist trigger.\n\n" #endif ; diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 03ba4530c08c..e3fa9c89f125 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -86,6 +86,8 @@ struct hist_trigger_attrs { char *keys_str; char *vals_str; char *sort_key_str; + bool pause; + bool cont; unsigned int map_bits; }; @@ -193,6 +195,11 @@ static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str) attrs->vals_str = kstrdup(str, GFP_KERNEL); else if (strncmp(str, "sort=", strlen("sort=")) == 0) attrs->sort_key_str = kstrdup(str, GFP_KERNEL); + else if (strcmp(str, "pause") == 0) + attrs->pause = true; + else if ((strcmp(str, "cont") == 0) || + (strcmp(str, "continue") == 0)) + attrs->cont = true; else if (strncmp(str, "size=", strlen("size=")) == 0) { int map_bits = parse_map_size(str); @@ -871,7 +878,10 @@ static int event_hist_trigger_print(struct seq_file *m, if (data->filter_str) seq_printf(m, " if %s", data->filter_str); - seq_puts(m, " [active]"); + if (data->paused) + seq_puts(m, " [paused]"); + else + seq_puts(m, " [active]"); seq_putc(m, '\n'); @@ -910,16 +920,30 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops, struct event_trigger_data *data, struct trace_event_file *file) { + struct hist_trigger_data *hist_data = data->private_data; struct event_trigger_data *test; int ret = 0; list_for_each_entry_rcu(test, &file->triggers, list) { if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) { - ret = -EEXIST; + if (hist_data->attrs->pause) + test->paused = true; + else if (hist_data->attrs->cont) + test->paused = false; + else + ret = -EEXIST; goto out; } } + if (hist_data->attrs->cont) { + ret = -ENOENT; + goto out; + } + + if (hist_data->attrs->pause) + data->paused = true; + if (data->ops->init) { ret = data->ops->init(data->ops, data); if (ret < 0) @@ -1011,7 +1035,8 @@ static int event_hist_trigger_func(struct event_command *cmd_ops, * triggers registered a failure too. */ if (!ret) { - ret = -ENOENT; + if (!(attrs->pause || attrs->cont)) + ret = -ENOENT; goto out_free; } else if (ret < 0) goto out_free; -- 2.20.1