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tools lib traceevent: Add pevent_data_pid_from_comm()

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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: Steven 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: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Steven Rostedt (Red Hat) 2015-03-24 09:57:52 -04:00 committed by Arnaldo Carvalho de Melo
parent 5542629696
commit 2771984c7f
2 changed files with 95 additions and 0 deletions
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90
tools/lib/traceevent/event-parse.c
View file

@ -4954,6 +4954,96 @@ const char *pevent_data_comm_from_pid(struct pevent *pevent, int pid)
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
* @s: the trace_seq to write to

5
tools/lib/traceevent/event-parse.h
View file

@ -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);
int pevent_data_pid(struct pevent *pevent, struct pevent_record *rec);
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,
struct pevent_record *record);
int pevent_strerror(struct pevent *pevent, enum pevent_errno errnum,