perf tools: Simplify debugfs mountpoint handling code

We don't need to have two PATH_MAX char sized arrays holding it, just
one in util/debugfs.c will do.

Also rename debugfs_path to tracing_events_path, as it is not the path
to debugfs, that is debugfs_mountpoint. Both are now accessible.

This will allow accessing this code in the perf python binding without
having to drag in perf.c and util/parse-events.c.

The defaults for these variables are the canonical "/sys/kernel/debug"
and "/sys/kernel/debug/tracing/events/", removing the need for simple
tools to call debugfs_mount(NULL).

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-ug9jvtjrsqbluuhqqxpvg30f@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 4 insertions, 29 deletions

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 73d0cac8b67e..2b2e225a4d4c 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -29,8 +29,6 @@ struct pager_config {
 	int val;
 };
 
-static char debugfs_mntpt[MAXPATHLEN];
-
 static int pager_command_config(const char *var, const char *value, void *data)
 {
 	struct pager_config *c = data;
@@ -81,15 +79,6 @@ static void commit_pager_choice(void)
 	}
 }
 
-static void set_debugfs_path(void)
-{
-	char *path;
-
-	path = getenv(PERF_DEBUGFS_ENVIRONMENT);
-	snprintf(debugfs_path, MAXPATHLEN, "%s/%s", path ?: debugfs_mntpt,
-		 "tracing/events");
-}
-
 static int handle_options(const char ***argv, int *argc, int *envchanged)
 {
 	int handled = 0;
@@ -161,15 +150,14 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 				fprintf(stderr, "No directory given for --debugfs-dir.\n");
 				usage(perf_usage_string);
 			}
-			strncpy(debugfs_mntpt, (*argv)[1], MAXPATHLEN);
-			debugfs_mntpt[MAXPATHLEN - 1] = '\0';
+			debugfs_set_path((*argv)[1]);
 			if (envchanged)
 				*envchanged = 1;
 			(*argv)++;
 			(*argc)--;
 		} else if (!prefixcmp(cmd, CMD_DEBUGFS_DIR)) {
-			strncpy(debugfs_mntpt, cmd + strlen(CMD_DEBUGFS_DIR), MAXPATHLEN);
-			debugfs_mntpt[MAXPATHLEN - 1] = '\0';
+			debugfs_set_path(cmd + strlen(CMD_DEBUGFS_DIR));
+			fprintf(stderr, "dir: %s\n", debugfs_mountpoint);
 			if (envchanged)
 				*envchanged = 1;
 		} else {
@@ -281,7 +269,6 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 	if (use_pager == -1 && p->option & USE_PAGER)
 		use_pager = 1;
 	commit_pager_choice();
-	set_debugfs_path();
 
 	status = p->fn(argc, argv, prefix);
 	exit_browser(status);
@@ -416,17 +403,6 @@ static int run_argv(int *argcp, const char ***argv)
 	return done_alias;
 }
 
-/* mini /proc/mounts parser: searching for "^blah /mount/point debugfs" */
-static void get_debugfs_mntpt(void)
-{
-	const char *path = debugfs_mount(NULL);
-
-	if (path)
-		strncpy(debugfs_mntpt, path, sizeof(debugfs_mntpt));
-	else
-		debugfs_mntpt[0] = '\0';
-}
-
 static void pthread__block_sigwinch(void)
 {
 	sigset_t set;
@@ -453,7 +429,7 @@ int main(int argc, const char **argv)
 	if (!cmd)
 		cmd = "perf-help";
 	/* get debugfs mount point from /proc/mounts */
-	get_debugfs_mntpt();
+	debugfs_mount(NULL);
 	/*
 	 * "perf-xxxx" is the same as "perf xxxx", but we obviously:
 	 *
@@ -476,7 +452,6 @@ int main(int argc, const char **argv)
 	argc--;
 	handle_options(&argv, &argc, NULL);
 	commit_pager_choice();
-	set_debugfs_path();
 	set_buildid_dir();
 
 	if (argc > 0) {