perf target: Remove uid from target

Gathering threads with a uid by scanning /proc is inherently racy
leading to perf_event_open failures that quit perf. All users of the
functionality now use BPF filters, so remove uid and uid_str from
target.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250604174545.2853620-10-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

tools/perf/builtin-ftrace.c

@@ -1663,7 +1663,6 @@ int cmd_ftrace(int argc, const char **argv)
 	int (*cmd_func)(struct perf_ftrace *) = NULL;
 	struct perf_ftrace ftrace = {
 		.tracer = DEFAULT_TRACER,
-		.target = { .uid = UINT_MAX, },
 	};
 	const struct option common_options[] = {
 	OPT_STRING('p', "pid", &ftrace.target.pid, "pid",

tools/perf/builtin-kvm.c

@@ -1871,8 +1871,6 @@ static int kvm_events_live(struct perf_kvm_stat *kvm,
 	kvm->opts.user_interval = 1;
 	kvm->opts.mmap_pages = 512;
 	kvm->opts.target.uses_mmap = false;
-	kvm->opts.target.uid_str = NULL;
-	kvm->opts.target.uid = UINT_MAX;
 
 	symbol__init(NULL);
 	disable_buildid_cache();

tools/perf/builtin-stat.c

@@ -108,9 +108,7 @@ static struct parse_events_option_args parse_events_option_args = {
 
 static bool all_counters_use_bpf = true;
 
-static struct target target = {
+static struct target target;
-	.uid	= UINT_MAX,
-};
 
 static volatile sig_atomic_t	child_pid			= -1;
 static int			detailed_run			=  0;

tools/perf/builtin-trace.c

@@ -5399,7 +5399,6 @@ int cmd_trace(int argc, const char **argv)
 	struct trace trace = {
 		.opts = {
 			.target = {
-				.uid	   = UINT_MAX,
 				.uses_mmap = true,
 			},
 			.user_freq     = UINT_MAX,

tools/perf/tests/backward-ring-buffer.c

@@ -91,7 +91,6 @@ static int test__backward_ring_buffer(struct test_suite *test __maybe_unused, in
 	struct parse_events_error parse_error;
 	struct record_opts opts = {
 		.target = {
-			.uid = UINT_MAX,
 			.uses_mmap = true,
 		},
 		.freq	      = 0,

tools/perf/tests/event-times.c

@@ -17,9 +17,7 @@
 static int attach__enable_on_exec(struct evlist *evlist)
 {
 	struct evsel *evsel = evlist__last(evlist);
-	struct target target = {
+	struct target target = {};
-		.uid = UINT_MAX,
-	};
 	const char *argv[] = { "true", NULL, };
 	char sbuf[STRERR_BUFSIZE];
 	int err;

tools/perf/tests/openat-syscall-tp-fields.c

@@ -28,7 +28,6 @@ static int test__syscall_openat_tp_fields(struct test_suite *test __maybe_unused
 {
 	struct record_opts opts = {
 		.target = {
-			.uid = UINT_MAX,
 			.uses_mmap = true,
 		},
 		.no_buffering = true,

tools/perf/tests/perf-record.c

@@ -45,7 +45,6 @@ static int test__PERF_RECORD(struct test_suite *test __maybe_unused, int subtest
 {
 	struct record_opts opts = {
 		.target = {
-			.uid = UINT_MAX,
 			.uses_mmap = true,
 		},
 		.no_buffering = true,

tools/perf/tests/task-exit.c

@@ -46,7 +46,6 @@ static int test__task_exit(struct test_suite *test __maybe_unused, int subtest _
 	struct evsel *evsel;
 	struct evlist *evlist;
 	struct target target = {
-		.uid		= UINT_MAX,
 		.uses_mmap	= true,
 	};
 	const char *argv[] = { "true", NULL };

tools/perf/util/bpf-filter.c

@@ -450,7 +450,7 @@ int perf_bpf_filter__prepare(struct evsel *evsel, struct target *target)
 	struct bpf_program *prog;
 	struct bpf_link *link;
 	struct perf_bpf_filter_entry *entry;
-	bool needs_idx_hash = !target__has_cpu(target) && !target->uid_str;
+	bool needs_idx_hash = !target__has_cpu(target);
 
 	entry = calloc(MAX_FILTERS, sizeof(*entry));
 	if (entry == NULL)

tools/perf/util/evlist.c

@@ -1006,8 +1006,7 @@ int evlist__create_maps(struct evlist *evlist, struct target *target)
 	 * per-thread data. thread_map__new_str will call
 	 * thread_map__new_all_cpus to enumerate all threads.
 	 */
-	threads = thread_map__new_str(target->pid, target->tid, target->uid,
+	threads = thread_map__new_str(target->pid, target->tid, UINT_MAX, all_threads);
-				      all_threads);
 
 	if (!threads)
 		return -1;

tools/perf/util/target.c

@@ -28,20 +28,6 @@ enum target_errno target__validate(struct target *target)
 			ret = TARGET_ERRNO__PID_OVERRIDE_CPU;
 	}
 
-	/* UID and PID are mutually exclusive */
-	if (target->tid && target->uid_str) {
-		target->uid_str = NULL;
-		if (ret == TARGET_ERRNO__SUCCESS)
-			ret = TARGET_ERRNO__PID_OVERRIDE_UID;
-	}
-
-	/* UID and CPU are mutually exclusive */
-	if (target->uid_str && target->cpu_list) {
-		target->cpu_list = NULL;
-		if (ret == TARGET_ERRNO__SUCCESS)
-			ret = TARGET_ERRNO__UID_OVERRIDE_CPU;
-	}
-
 	/* PID and SYSTEM are mutually exclusive */
 	if (target->tid && target->system_wide) {
 		target->system_wide = false;
@@ -49,13 +35,6 @@ enum target_errno target__validate(struct target *target)
 			ret = TARGET_ERRNO__PID_OVERRIDE_SYSTEM;
 	}
 
-	/* UID and SYSTEM are mutually exclusive */
-	if (target->uid_str && target->system_wide) {
-		target->system_wide = false;
-		if (ret == TARGET_ERRNO__SUCCESS)
-			ret = TARGET_ERRNO__UID_OVERRIDE_SYSTEM;
-	}
-
 	/* BPF and CPU are mutually exclusive */
 	if (target->bpf_str && target->cpu_list) {
 		target->cpu_list = NULL;
@@ -70,13 +49,6 @@ enum target_errno target__validate(struct target *target)
 			ret = TARGET_ERRNO__BPF_OVERRIDE_PID;
 	}
 
-	/* BPF and UID are mutually exclusive */
-	if (target->bpf_str && target->uid_str) {
-		target->uid_str = NULL;
-		if (ret == TARGET_ERRNO__SUCCESS)
-			ret = TARGET_ERRNO__BPF_OVERRIDE_UID;
-	}
-
 	/* BPF and THREADS are mutually exclusive */
 	if (target->bpf_str && target->per_thread) {
 		target->per_thread = false;
@@ -124,31 +96,19 @@ uid_t parse_uid(const char *str)
 	return result->pw_uid;
 }
 
-enum target_errno target__parse_uid(struct target *target)
-{
-	target->uid = parse_uid(target->uid_str);
-
-	return target->uid != UINT_MAX ? TARGET_ERRNO__SUCCESS : TARGET_ERRNO__INVALID_UID;
-}
-
 /*
  * This must have a same ordering as the enum target_errno.
  */
 static const char *target__error_str[] = {
 	"PID/TID switch overriding CPU",
-	"PID/TID switch overriding UID",
-	"UID switch overriding CPU",
 	"PID/TID switch overriding SYSTEM",
-	"UID switch overriding SYSTEM",
 	"SYSTEM/CPU switch overriding PER-THREAD",
 	"BPF switch overriding CPU",
 	"BPF switch overriding PID/TID",
-	"BPF switch overriding UID",
 	"BPF switch overriding THREAD",
-	"Invalid User: %s",
 };
 
-int target__strerror(struct target *target, int errnum,
+int target__strerror(struct target *target __maybe_unused, int errnum,
 			  char *buf, size_t buflen)
 {
 	int idx;
@@ -173,10 +133,6 @@ int target__strerror(struct target *target, int errnum,
 		snprintf(buf, buflen, "%s", msg);
 		break;
 
-	case TARGET_ERRNO__INVALID_UID:
-		snprintf(buf, buflen, msg, target->uid_str);
-		break;
-
 	default:
 		/* cannot reach here */
 		break;

tools/perf/util/target.h

@@ -9,9 +9,7 @@ struct target {
 	const char   *pid;
 	const char   *tid;
 	const char   *cpu_list;
-	const char   *uid_str;
 	const char   *bpf_str;
-	uid_t	     uid;
 	bool	     system_wide;
 	bool	     uses_mmap;
 	bool	     default_per_cpu;
@@ -36,32 +34,24 @@ enum target_errno {
 
 	/* for target__validate() */
 	TARGET_ERRNO__PID_OVERRIDE_CPU	= __TARGET_ERRNO__START,
-	TARGET_ERRNO__PID_OVERRIDE_UID,
-	TARGET_ERRNO__UID_OVERRIDE_CPU,
 	TARGET_ERRNO__PID_OVERRIDE_SYSTEM,
-	TARGET_ERRNO__UID_OVERRIDE_SYSTEM,
 	TARGET_ERRNO__SYSTEM_OVERRIDE_THREAD,
 	TARGET_ERRNO__BPF_OVERRIDE_CPU,
 	TARGET_ERRNO__BPF_OVERRIDE_PID,
-	TARGET_ERRNO__BPF_OVERRIDE_UID,
 	TARGET_ERRNO__BPF_OVERRIDE_THREAD,
 
-	/* for target__parse_uid() */
-	TARGET_ERRNO__INVALID_UID,
-
 	__TARGET_ERRNO__END,
 };
 
 enum target_errno target__validate(struct target *target);
 
 uid_t parse_uid(const char *str);
-enum target_errno target__parse_uid(struct target *target);
 
 int target__strerror(struct target *target, int errnum, char *buf, size_t buflen);
 
 static inline bool target__has_task(struct target *target)
 {
-	return target->tid || target->pid || target->uid_str;
+	return target->tid || target->pid;
 }
 
 static inline bool target__has_cpu(struct target *target)