Re: [PATCH v11 13/28] tracing: Add hist trigger support for pausing and continuing a trace

2015-11-03 Thread Tom Zanussi 
On Tue, 2015-11-03 at 17:38 +0900, Namhyung Kim wrote:
> On Thu, Oct 22, 2015 at 01:14:17PM -0500, Tom Zanussi wrote:
> > 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
> 
> What if 'cont' is used for a non-existing hist?  I think it should
> fail with -ENOENT but it seems that it'd create a new hist trigger..
> 

You're right - 'pause' is the only one that should create a new trigger,
not 'cont' or 'clear'.

Thanks,

Tom

> Thanks,
> Namhyung
> 
> 
> > 
> > Signed-off-by: Tom Zanussi 
> > Tested-by: Masami Hiramatsu 
> > ---
> >  kernel/trace/trace.c |  7 ++-
> >  kernel/trace/trace_events_hist.c | 26 +++---
> >  2 files changed, 29 insertions(+), 4 deletions(-)
> > 
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index efa8d05..a223959 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -3802,6 +3802,7 @@ static const char readme_msg[] =
> > "\t[:values= > "\t[:sort=field1,field2,...]\n"
> > "\t[:size=#entries]\n"
> > +   "\t[:pause][:continue]\n"
> > "\t[if ]\n\n"
> > "\tWhen a matching event is hit, an entry is added to a hash\n"
> > "\ttable using the key(s) and value(s) named, and the value of a\n"
> > @@ -3816,7 +3817,11 @@ static const char readme_msg[] =
> > "\tused to specify more or fewer than the default 2048 entries\n"
> > "\tfor the hashtable size.\n\n"
> > "\tReading the 'hist' file for the event will dump the hash\n"
> > -   "\ttable in its entirety to stdout."
> > +   "\ttable in its entirety to stdout.\n\n"
> > +   "\tThe 'pause' parameter can be used to pause an existing hist\n"
> > +   "\ttrigger or to start a hist trigger but not log any events\n"
> > +   "\tuntil told to do so.  'continue' can be used to start or\n"
> > +   "\trestart a paused hist trigger.\n\n"
> >  #endif
> >  ;
> >  
> > diff --git a/kernel/trace/trace_events_hist.c 
> > b/kernel/trace/trace_events_hist.c
> > index 4fc3136..8753c3b 100644
> > --- a/kernel/trace/trace_events_hist.c
> > +++ b/kernel/trace/trace_events_hist.c
> > @@ -78,6 +78,8 @@ struct hist_trigger_attrs {
> > char*keys_str;
> > char*vals_str;
> > char*sort_key_str;
> > +   boolpause;
> > +   boolcont;
> > unsigned intmap_bits;
> >  };
> >  
> > @@ -184,6 +186,11 @@ 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")))
> > attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
> > +   else if (!strncmp(str, "pause", strlen("pause")))
> > +   attrs->pause = true;
> > +   else if (!strncmp(str, "continue", strlen("continue")) ||
> > +!strncmp(str, "cont", strlen("cont")))
> > +   attrs->cont = true;
> > else if (!strncmp(str, "size", strlen("size"))) {
> > int map_bits = parse_map_size(str);
> >  
> > @@ -843,7 +850,10 @@ 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');
> >  
> > @@ -882,16 +892,25 @@ 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, >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->pause)
> > +   data->paused = true;
> > +
> > if (data->ops->init) {
> > ret = data->ops->init(data->ops,

Re: [PATCH v11 13/28] tracing: Add hist trigger support for pausing and continuing a trace

2015-11-03 Thread Namhyung Kim 
On Thu, Oct 22, 2015 at 01:14:17PM -0500, Tom Zanussi wrote:
> 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

What if 'cont' is used for a non-existing hist?  I think it should
fail with -ENOENT but it seems that it'd create a new hist trigger..

Thanks,
Namhyung


> 
> Signed-off-by: Tom Zanussi 
> Tested-by: Masami Hiramatsu 
> ---
>  kernel/trace/trace.c |  7 ++-
>  kernel/trace/trace_events_hist.c | 26 +++---
>  2 files changed, 29 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index efa8d05..a223959 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -3802,6 +3802,7 @@ static const char readme_msg[] =
>   "\t[:values=   "\t[:sort=field1,field2,...]\n"
>   "\t[:size=#entries]\n"
> + "\t[:pause][:continue]\n"
>   "\t[if ]\n\n"
>   "\tWhen a matching event is hit, an entry is added to a hash\n"
>   "\ttable using the key(s) and value(s) named, and the value of a\n"
> @@ -3816,7 +3817,11 @@ static const char readme_msg[] =
>   "\tused to specify more or fewer than the default 2048 entries\n"
>   "\tfor the hashtable size.\n\n"
>   "\tReading the 'hist' file for the event will dump the hash\n"
> - "\ttable in its entirety to stdout."
> + "\ttable in its entirety to stdout.\n\n"
> + "\tThe 'pause' parameter can be used to pause an existing hist\n"
> + "\ttrigger or to start a hist trigger but not log any events\n"
> + "\tuntil told to do so.  'continue' can be used to start or\n"
> + "\trestart a paused hist trigger.\n\n"
>  #endif
>  ;
>  
> diff --git a/kernel/trace/trace_events_hist.c 
> b/kernel/trace/trace_events_hist.c
> index 4fc3136..8753c3b 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -78,6 +78,8 @@ struct hist_trigger_attrs {
>   char*keys_str;
>   char*vals_str;
>   char*sort_key_str;
> + boolpause;
> + boolcont;
>   unsigned intmap_bits;
>  };
>  
> @@ -184,6 +186,11 @@ 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")))
>   attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
> + else if (!strncmp(str, "pause", strlen("pause")))
> + attrs->pause = true;
> + else if (!strncmp(str, "continue", strlen("continue")) ||
> +  !strncmp(str, "cont", strlen("cont")))
> + attrs->cont = true;
>   else if (!strncmp(str, "size", strlen("size"))) {
>   int map_bits = parse_map_size(str);
>  
> @@ -843,7 +850,10 @@ 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');
>  
> @@ -882,16 +892,25 @@ 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, >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->pause)
> + data->paused = true;
> +
>   if (data->ops->init) {
>   ret = data->ops->init(data->ops, data);
>   if (ret < 0)
> @@ -984,7 +1003,8 @@ 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))

Re: [PATCH v11 13/28] tracing: Add hist trigger support for pausing and continuing a trace

2015-11-03 Thread Namhyung Kim 
On Thu, Oct 22, 2015 at 01:14:17PM -0500, Tom Zanussi wrote:
> 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

What if 'cont' is used for a non-existing hist?  I think it should
fail with -ENOENT but it seems that it'd create a new hist trigger..

Thanks,
Namhyung


> 
> Signed-off-by: Tom Zanussi 
> Tested-by: Masami Hiramatsu 
> ---
>  kernel/trace/trace.c |  7 ++-
>  kernel/trace/trace_events_hist.c | 26 +++---
>  2 files changed, 29 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index efa8d05..a223959 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -3802,6 +3802,7 @@ static const char readme_msg[] =
>   "\t[:values=   "\t[:sort=field1,field2,...]\n"
>   "\t[:size=#entries]\n"
> + "\t[:pause][:continue]\n"
>   "\t[if ]\n\n"
>   "\tWhen a matching event is hit, an entry is added to a hash\n"
>   "\ttable using the key(s) and value(s) named, and the value of a\n"
> @@ -3816,7 +3817,11 @@ static const char readme_msg[] =
>   "\tused to specify more or fewer than the default 2048 entries\n"
>   "\tfor the hashtable size.\n\n"
>   "\tReading the 'hist' file for the event will dump the hash\n"
> - "\ttable in its entirety to stdout."
> + "\ttable in its entirety to stdout.\n\n"
> + "\tThe 'pause' parameter can be used to pause an existing hist\n"
> + "\ttrigger or to start a hist trigger but not log any events\n"
> + "\tuntil told to do so.  'continue' can be used to start or\n"
> + "\trestart a paused hist trigger.\n\n"
>  #endif
>  ;
>  
> diff --git a/kernel/trace/trace_events_hist.c 
> b/kernel/trace/trace_events_hist.c
> index 4fc3136..8753c3b 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -78,6 +78,8 @@ struct hist_trigger_attrs {
>   char*keys_str;
>   char*vals_str;
>   char*sort_key_str;
> + boolpause;
> + boolcont;
>   unsigned intmap_bits;
>  };
>  
> @@ -184,6 +186,11 @@ 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")))
>   attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
> + else if (!strncmp(str, "pause", strlen("pause")))
> + attrs->pause = true;
> + else if (!strncmp(str, "continue", strlen("continue")) ||
> +  !strncmp(str, "cont", strlen("cont")))
> + attrs->cont = true;
>   else if (!strncmp(str, "size", strlen("size"))) {
>   int map_bits = parse_map_size(str);
>  
> @@ -843,7 +850,10 @@ 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');
>  
> @@ -882,16 +892,25 @@ 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, >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->pause)
> + data->paused = true;
> +
>   if (data->ops->init) {
>   ret = data->ops->init(data->ops, data);
>   if (ret < 0)
> @@ -984,7 +1003,8 @@ static int event_hist_trigger_func(struct event_command 
> *cmd_ops,
>* triggers registered a failure too.
>*/
>   if

Re: [PATCH v11 13/28] tracing: Add hist trigger support for pausing and continuing a trace

2015-11-03 Thread Tom Zanussi 
On Tue, 2015-11-03 at 17:38 +0900, Namhyung Kim wrote:
> On Thu, Oct 22, 2015 at 01:14:17PM -0500, Tom Zanussi wrote:
> > 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
> 
> What if 'cont' is used for a non-existing hist?  I think it should
> fail with -ENOENT but it seems that it'd create a new hist trigger..
> 

You're right - 'pause' is the only one that should create a new trigger,
not 'cont' or 'clear'.

Thanks,

Tom

> Thanks,
> Namhyung
> 
> 
> > 
> > Signed-off-by: Tom Zanussi 
> > Tested-by: Masami Hiramatsu 
> > ---
> >  kernel/trace/trace.c |  7 ++-
> >  kernel/trace/trace_events_hist.c | 26 +++---
> >  2 files changed, 29 insertions(+), 4 deletions(-)
> > 
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index efa8d05..a223959 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -3802,6 +3802,7 @@ static const char readme_msg[] =
> > "\t[:values= > "\t[:sort=field1,field2,...]\n"
> > "\t[:size=#entries]\n"
> > +   "\t[:pause][:continue]\n"
> > "\t[if ]\n\n"
> > "\tWhen a matching event is hit, an entry is added to a hash\n"
> > "\ttable using the key(s) and value(s) named, and the value of a\n"
> > @@ -3816,7 +3817,11 @@ static const char readme_msg[] =
> > "\tused to specify more or fewer than the default 2048 entries\n"
> > "\tfor the hashtable size.\n\n"
> > "\tReading the 'hist' file for the event will dump the hash\n"
> > -   "\ttable in its entirety to stdout."
> > +   "\ttable in its entirety to stdout.\n\n"
> > +   "\tThe 'pause' parameter can be used to pause an existing hist\n"
> > +   "\ttrigger or to start a hist trigger but not log any events\n"
> > +   "\tuntil told to do so.  'continue' can be used to start or\n"
> > +   "\trestart a paused hist trigger.\n\n"
> >  #endif
> >  ;
> >  
> > diff --git a/kernel/trace/trace_events_hist.c 
> > b/kernel/trace/trace_events_hist.c
> > index 4fc3136..8753c3b 100644
> > --- a/kernel/trace/trace_events_hist.c
> > +++ b/kernel/trace/trace_events_hist.c
> > @@ -78,6 +78,8 @@ struct hist_trigger_attrs {
> > char*keys_str;
> > char*vals_str;
> > char*sort_key_str;
> > +   boolpause;
> > +   boolcont;
> > unsigned intmap_bits;
> >  };
> >  
> > @@ -184,6 +186,11 @@ 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")))
> > attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
> > +   else if (!strncmp(str, "pause", strlen("pause")))
> > +   attrs->pause = true;
> > +   else if (!strncmp(str, "continue", strlen("continue")) ||
> > +!strncmp(str, "cont", strlen("cont")))
> > +   attrs->cont = true;
> > else if (!strncmp(str, "size", strlen("size"))) {
> > int map_bits = parse_map_size(str);
> >  
> > @@ -843,7 +850,10 @@ 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');
> >  
> > @@ -882,16 +892,25 @@ 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, >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->pause)
> > +   data->paused = true;
> >

[PATCH v11 13/28] tracing: Add hist trigger support for pausing and continuing a trace

2015-10-22 Thread Tom Zanussi 
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

Signed-off-by: Tom Zanussi 
Tested-by: Masami Hiramatsu 
---
 kernel/trace/trace.c |  7 ++-
 kernel/trace/trace_events_hist.c | 26 +++---
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index efa8d05..a223959 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3802,6 +3802,7 @@ static const char readme_msg[] =
"\t[:values=]\n\n"
"\tWhen a matching event is hit, an entry is added to a hash\n"
"\ttable using the key(s) and value(s) named, and the value of a\n"
@@ -3816,7 +3817,11 @@ static const char readme_msg[] =
"\tused to specify more or fewer than the default 2048 entries\n"
"\tfor the hashtable size.\n\n"
"\tReading the 'hist' file for the event will dump the hash\n"
-   "\ttable in its entirety to stdout."
+   "\ttable in its entirety to stdout.\n\n"
+   "\tThe 'pause' parameter can be used to pause an existing hist\n"
+   "\ttrigger or to start a hist trigger but not log any events\n"
+   "\tuntil told to do so.  'continue' can be used to start or\n"
+   "\trestart a paused hist trigger.\n\n"
 #endif
 ;
 
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 4fc3136..8753c3b 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -78,6 +78,8 @@ struct hist_trigger_attrs {
char*keys_str;
char*vals_str;
char*sort_key_str;
+   boolpause;
+   boolcont;
unsigned intmap_bits;
 };
 
@@ -184,6 +186,11 @@ 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")))
attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
+   else if (!strncmp(str, "pause", strlen("pause")))
+   attrs->pause = true;
+   else if (!strncmp(str, "continue", strlen("continue")) ||
+!strncmp(str, "cont", strlen("cont")))
+   attrs->cont = true;
else if (!strncmp(str, "size", strlen("size"))) {
int map_bits = parse_map_size(str);
 
@@ -843,7 +850,10 @@ 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');
 
@@ -882,16 +892,25 @@ 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, >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->pause)
+   data->paused = true;
+
if (data->ops->init) {
ret = data->ops->init(data->ops, data);
if (ret < 0)
@@ -984,7 +1003,8 @@ 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;
-- 
1.9.3

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[PATCH v11 13/28] tracing: Add hist trigger support for pausing and continuing a trace

2015-10-22 Thread Tom Zanussi 
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

Signed-off-by: Tom Zanussi 
Tested-by: Masami Hiramatsu 
---
 kernel/trace/trace.c |  7 ++-
 kernel/trace/trace_events_hist.c | 26 +++---
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index efa8d05..a223959 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3802,6 +3802,7 @@ static const char readme_msg[] =
"\t[:values=vals_str = kstrdup(str, GFP_KERNEL);
else if (!strncmp(str, "sort", strlen("sort")))
attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
+   else if (!strncmp(str, "pause", strlen("pause")))
+   attrs->pause = true;
+   else if (!strncmp(str, "continue", strlen("continue")) ||
+!strncmp(str, "cont", strlen("cont")))
+   attrs->cont = true;
else if (!strncmp(str, "size", strlen("size"))) {
int map_bits = parse_map_size(str);
 
@@ -843,7 +850,10 @@ 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');
 
@@ -882,16 +892,25 @@ 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, >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->pause)
+   data->paused = true;
+
if (data->ops->init) {
ret = data->ops->init(data->ops, data);
if (ret < 0)
@@ -984,7 +1003,8 @@ 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;
-- 
1.9.3

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