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Subject[tip:perf/urgent] tools lib traceevent: Introduce new libtracevent API: tep_override_comm()
Commit-ID:  ca3958b1c0968a6f3105e211355f128ce871e796
Gitweb: https://git.kernel.org/tip/ca3958b1c0968a6f3105e211355f128ce871e796
Author: Tzvetomir Stoyanov <tstoyanov@vmware.com>
AuthorDate: Fri, 30 Nov 2018 10:44:11 -0500
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 8 Jan 2019 13:28:13 -0300

tools lib traceevent: Introduce new libtracevent API: tep_override_comm()

This patch adds a new API of tracevent library: tep_override_comm() It
registers a pid / command mapping. If a mapping with the same pid
already exists, the entry is updated with the new command.

Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
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/20181130154648.038915912@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/lib/traceevent/event-parse.c | 69 +++++++++++++++++++++++++++++---------
tools/lib/traceevent/event-parse.h | 1 +
2 files changed, 55 insertions(+), 15 deletions(-)

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 69a96e39f0ab..156e513074b2 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -232,11 +232,13 @@ int tep_pid_is_registered(struct tep_handle *pevent, int pid)
* we must add this pid. This is much slower than when cmdlines
* are added before the array is initialized.
*/
-static int add_new_comm(struct tep_handle *pevent, const char *comm, int pid)
+static int add_new_comm(struct tep_handle *pevent,
+ const char *comm, int pid, bool override)
{
struct cmdline *cmdlines = pevent->cmdlines;
- const struct cmdline *cmdline;
+ struct cmdline *cmdline;
struct cmdline key;
+ char *new_comm;

if (!pid)
return 0;
@@ -247,8 +249,19 @@ static int add_new_comm(struct tep_handle *pevent, const char *comm, int pid)
cmdline = bsearch(&key, pevent->cmdlines, pevent->cmdline_count,
sizeof(*pevent->cmdlines), cmdline_cmp);
if (cmdline) {
- errno = EEXIST;
- return -1;
+ if (!override) {
+ errno = EEXIST;
+ return -1;
+ }
+ new_comm = strdup(comm);
+ if (!new_comm) {
+ errno = ENOMEM;
+ return -1;
+ }
+ free(cmdline->comm);
+ cmdline->comm = new_comm;
+
+ return 0;
}

cmdlines = realloc(cmdlines, sizeof(*cmdlines) * (pevent->cmdline_count + 1));
@@ -275,21 +288,13 @@ static int add_new_comm(struct tep_handle *pevent, const char *comm, int pid)
return 0;
}

-/**
- * tep_register_comm - register a pid / comm mapping
- * @pevent: handle for the pevent
- * @comm: the command line to register
- * @pid: the pid to map the command line to
- *
- * This adds a mapping to search for command line names with
- * a given pid. The comm is duplicated.
- */
-int tep_register_comm(struct tep_handle *pevent, const char *comm, int pid)
+static int _tep_register_comm(struct tep_handle *pevent,
+ const char *comm, int pid, bool override)
{
struct cmdline_list *item;

if (pevent->cmdlines)
- return add_new_comm(pevent, comm, pid);
+ return add_new_comm(pevent, comm, pid, override);

item = malloc(sizeof(*item));
if (!item)
@@ -312,6 +317,40 @@ int tep_register_comm(struct tep_handle *pevent, const char *comm, int pid)
return 0;
}

+/**
+ * tep_register_comm - register a pid / comm mapping
+ * @pevent: handle for the pevent
+ * @comm: the command line to register
+ * @pid: the pid to map the command line to
+ *
+ * This adds a mapping to search for command line names with
+ * a given pid. The comm is duplicated. If a command with the same pid
+ * already exist, -1 is returned and errno is set to EEXIST
+ */
+int tep_register_comm(struct tep_handle *pevent, const char *comm, int pid)
+{
+ return _tep_register_comm(pevent, comm, pid, false);
+}
+
+/**
+ * tep_override_comm - register a pid / comm mapping
+ * @pevent: handle for the pevent
+ * @comm: the command line to register
+ * @pid: the pid to map the command line to
+ *
+ * This adds a mapping to search for command line names with
+ * a given pid. The comm is duplicated. If a command with the same pid
+ * already exist, the command string is udapted with the new one
+ */
+int tep_override_comm(struct tep_handle *pevent, const char *comm, int pid)
+{
+ if (!pevent->cmdlines && cmdline_init(pevent)) {
+ errno = ENOMEM;
+ return -1;
+ }
+ return _tep_register_comm(pevent, comm, pid, true);
+}
+
int tep_register_trace_clock(struct tep_handle *pevent, const char *trace_clock)
{
pevent->trace_clock = strdup(trace_clock);
diff --git a/tools/lib/traceevent/event-parse.h b/tools/lib/traceevent/event-parse.h
index 35d37087d3c5..e6f4249910e6 100644
--- a/tools/lib/traceevent/event-parse.h
+++ b/tools/lib/traceevent/event-parse.h
@@ -432,6 +432,7 @@ int tep_set_function_resolver(struct tep_handle *pevent,
tep_func_resolver_t *func, void *priv);
void tep_reset_function_resolver(struct tep_handle *pevent);
int tep_register_comm(struct tep_handle *pevent, const char *comm, int pid);
+int tep_override_comm(struct tep_handle *pevent, const char *comm, int pid);
int tep_register_trace_clock(struct tep_handle *pevent, const char *trace_clock);
int tep_register_function(struct tep_handle *pevent, char *name,
unsigned long long addr, char *mod);
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