Introduce new libtracevent API: tep_override_comm()
diff mbox series

Message ID 20180830150900.27412-1-tz.stoyanov@gmail.com
State New, archived
Headers show
Series
  • Introduce new libtracevent API: tep_override_comm()
Related show

Commit Message

Tzvetomir Stoyanov (VMware) Aug. 30, 2018, 3:09 p.m. UTC
Added a new API of tracevent library: tep_override_comm()
It registers a pid / comm mapping. If a mapping with the same
pid already exists, the entry is updated with the new comm.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/traceevent/event-parse.h |  1 +
 lib/traceevent/event-parse.c     | 67 +++++++++++++++++++++++++-------
 2 files changed, 53 insertions(+), 15 deletions(-)

Comments

Steven Rostedt Aug. 30, 2018, 4:32 p.m. UTC | #1
On Thu, 30 Aug 2018 18:09:00 +0300
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> Added a new API of tracevent library: tep_override_comm()
> It registers a pid / comm mapping. If a mapping with the same
> pid already exists, the entry is updated with the new comm.
> 
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>  include/traceevent/event-parse.h |  1 +
>  lib/traceevent/event-parse.c     | 67 +++++++++++++++++++++++++-------
>  2 files changed, 53 insertions(+), 15 deletions(-)
> 
> diff --git a/include/traceevent/event-parse.h b/include/traceevent/event-parse.h
> index 713a4e4..0dcc024 100644
> --- a/include/traceevent/event-parse.h
> +++ b/include/traceevent/event-parse.h
> @@ -607,6 +607,7 @@ 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);
> diff --git a/lib/traceevent/event-parse.c b/lib/traceevent/event-parse.c
> index ce1e202..e40f63c 100644
> --- a/lib/traceevent/event-parse.c
> +++ b/lib/traceevent/event-parse.c
> @@ -230,10 +230,11 @@ 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, int overrite)

Typo, should be "overwrite" or "override". Also make it a "bool" type.

>  {
>  	struct cmdline *cmdlines = pevent->cmdlines;
> -	const struct cmdline *cmdline;
> +	struct cmdline *cmdline;
>  	struct cmdline key;
>  
>  	if (!pid)
> @@ -245,8 +246,18 @@ 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 (!overrite) {
> +			errno = EEXIST;
> +			return -1;
> +		}
> +		if (cmdline->comm)
> +			free(cmdline->comm);
> +		cmdline->comm = strdup(comm);

We don't want to lose the old comm if the new comm fails to be
allocated. Thus, use a temp variable to save the strdup().

		char *new_comm;

		new_comm = strdup(comm);
		if (!new_comm) {
			errno = ENOMEM;
			return -1;
		}

		free(cmdline->comm);
		cmdline->comm = new_comm;

> +		if(!cmdline->comm) {
> +			errno = ENOMEM;
> +			return -1;
> +		}
> +		return 0;
>  	}
>  
>  	cmdlines = realloc(cmdlines, sizeof(*cmdlines) * (pevent->cmdline_count + 1));
> @@ -273,21 +284,13 @@ 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, int overrite)

Same comment here for "overrite".

>  {
>  	struct cmdline_list *item;
>  
>  	if (pevent->cmdlines)
> -		return add_new_comm(pevent, comm, pid);
> +		return add_new_comm(pevent, comm, pid, overrite);
>  
>  	item = malloc(sizeof(*item));
>  	if (!item)
> @@ -310,6 +313,40 @@ 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, 0);

Pass in "false" instead of 0.

> +}
> +
> +/**
> + * 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, 1);

Pass in "true" instead of 1.

> +}
> +

Rest looks good.

Thanks Tzvetomir!

-- Steve

>  int tep_register_trace_clock(struct tep_handle *pevent, const char *trace_clock)
>  {
>  	pevent->trace_clock = strdup(trace_clock);

Patch
diff mbox series

diff --git a/include/traceevent/event-parse.h b/include/traceevent/event-parse.h
index 713a4e4..0dcc024 100644
--- a/include/traceevent/event-parse.h
+++ b/include/traceevent/event-parse.h
@@ -607,6 +607,7 @@  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);
diff --git a/lib/traceevent/event-parse.c b/lib/traceevent/event-parse.c
index ce1e202..e40f63c 100644
--- a/lib/traceevent/event-parse.c
+++ b/lib/traceevent/event-parse.c
@@ -230,10 +230,11 @@  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, int overrite)
 {
 	struct cmdline *cmdlines = pevent->cmdlines;
-	const struct cmdline *cmdline;
+	struct cmdline *cmdline;
 	struct cmdline key;
 
 	if (!pid)
@@ -245,8 +246,18 @@  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 (!overrite) {
+			errno = EEXIST;
+			return -1;
+		}
+		if (cmdline->comm)
+			free(cmdline->comm);
+		cmdline->comm = strdup(comm);
+		if(!cmdline->comm) {
+			errno = ENOMEM;
+			return -1;
+		}
+		return 0;
 	}
 
 	cmdlines = realloc(cmdlines, sizeof(*cmdlines) * (pevent->cmdline_count + 1));
@@ -273,21 +284,13 @@  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, int overrite)
 {
 	struct cmdline_list *item;
 
 	if (pevent->cmdlines)
-		return add_new_comm(pevent, comm, pid);
+		return add_new_comm(pevent, comm, pid, overrite);
 
 	item = malloc(sizeof(*item));
 	if (!item)
@@ -310,6 +313,40 @@  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, 0);
+}
+
+/**
+ * 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, 1);
+}
+
 int tep_register_trace_clock(struct tep_handle *pevent, const char *trace_clock)
 {
 	pevent->trace_clock = strdup(trace_clock);