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Commit 2771984c authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Arnaldo Carvalho de Melo
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tools lib traceevent: Add pevent_data_pid_from_comm() 



There is a pevent_data_comm_from_pid() that returns the cmdline stored for
a given pid in order for users to map pids to comms, but there's no method
to convert a comm back to a pid. This is useful for filters that specify
a comm instead of a PID (it's faster than searching each individual event).

Add a way to retrieve a comm from a pid. Since there can be more than one
pid associated to a comm, it returns a data structure that lets the user
iterate over all the saved comms for a given pid.

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20150324135923.001103479@goodmis.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 55426296

tools/lib/traceevent/event-parse.c

+90 −0
Original line number Original line Diff line number Diff line
@@ -4954,6 +4954,96 @@ const char *pevent_data_comm_from_pid(struct pevent *pevent, int pid) 
	return comm;

	return comm;

}

}





static struct cmdline *

pid_from_cmdlist(struct pevent *pevent, const char *comm, struct cmdline *next)

{

	struct cmdline_list *cmdlist = (struct cmdline_list *)next;



	if (cmdlist)

		cmdlist = cmdlist->next;

	else

		cmdlist = pevent->cmdlist;



	while (cmdlist && strcmp(cmdlist->comm, comm) != 0)

		cmdlist = cmdlist->next;



	return (struct cmdline *)cmdlist;

}



/**

 * pevent_data_pid_from_comm - return the pid from a given comm

 * @pevent: a handle to the pevent

 * @comm: the cmdline to find the pid from

 * @next: the cmdline structure to find the next comm

 *

 * This returns the cmdline structure that holds a pid for a given

 * comm, or NULL if none found. As there may be more than one pid for

 * a given comm, the result of this call can be passed back into

 * a recurring call in the @next paramater, and then it will find the

 * next pid.

 * Also, it does a linear seach, so it may be slow.

 */

struct cmdline *pevent_data_pid_from_comm(struct pevent *pevent, const char *comm,

					  struct cmdline *next)

{

	struct cmdline *cmdline;



	/*

	 * If the cmdlines have not been converted yet, then use

	 * the list.

	 */

	if (!pevent->cmdlines)

		return pid_from_cmdlist(pevent, comm, next);



	if (next) {

		/*

		 * The next pointer could have been still from

		 * a previous call before cmdlines were created

		 */

		if (next < pevent->cmdlines ||

		    next >= pevent->cmdlines + pevent->cmdline_count)

			next = NULL;

		else

			cmdline  = next++;

	}



	if (!next)

		cmdline = pevent->cmdlines;



	while (cmdline < pevent->cmdlines + pevent->cmdline_count) {

		if (strcmp(cmdline->comm, comm) == 0)

			return cmdline;

		cmdline++;

	}

	return NULL;

}



/**

 * pevent_cmdline_pid - return the pid associated to a given cmdline

 * @cmdline: The cmdline structure to get the pid from

 *

 * Returns the pid for a give cmdline. If @cmdline is NULL, then

 * -1 is returned.

 */

int pevent_cmdline_pid(struct pevent *pevent, struct cmdline *cmdline)

{

	struct cmdline_list *cmdlist = (struct cmdline_list *)cmdline;



	if (!cmdline)

		return -1;



	/*

	 * If cmdlines have not been created yet, or cmdline is

	 * not part of the array, then treat it as a cmdlist instead.

	 */

	if (!pevent->cmdlines ||

	    cmdline < pevent->cmdlines ||

	    cmdline >= pevent->cmdlines + pevent->cmdline_count)

		return cmdlist->pid;



	return cmdline->pid;

}



/**

/**

 * pevent_data_comm_from_pid - parse the data into the print format

 * pevent_data_comm_from_pid - parse the data into the print format

 * @s: the trace_seq to write to

 * @s: the trace_seq to write to

tools/lib/traceevent/event-parse.h

+5 −0
Original line number Original line Diff line number Diff line
@@ -678,6 +678,11 @@ int pevent_data_type(struct pevent *pevent, struct pevent_record *rec); 
struct event_format *pevent_data_event_from_type(struct pevent *pevent, int type);

struct event_format *pevent_data_event_from_type(struct pevent *pevent, int type);

int pevent_data_pid(struct pevent *pevent, struct pevent_record *rec);

int pevent_data_pid(struct pevent *pevent, struct pevent_record *rec);

const char *pevent_data_comm_from_pid(struct pevent *pevent, int pid);

const char *pevent_data_comm_from_pid(struct pevent *pevent, int pid);

struct cmdline;

struct cmdline *pevent_data_pid_from_comm(struct pevent *pevent, const char *comm,

					  struct cmdline *next);

int pevent_cmdline_pid(struct pevent *pevent, struct cmdline *cmdline);



void pevent_event_info(struct trace_seq *s, struct event_format *event,

void pevent_event_info(struct trace_seq *s, struct event_format *event,

		       struct pevent_record *record);

		       struct pevent_record *record);

int pevent_strerror(struct pevent *pevent, enum pevent_errno errnum,

int pevent_strerror(struct pevent *pevent, enum pevent_errno errnum,