1 files changed, 153 insertions, 0 deletions
diff --git a/tools/perf/util/comm.c b/tools/perf/util/comm.c
new file mode 100644
index 000000000..afb8d4fd2
--- /dev/null
+++ b/tools/perf/util/comm.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "comm.h"
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <linux/refcount.h>
+#include <linux/rbtree.h>
+#include <linux/zalloc.h>
+#include "rwsem.h"
+
+struct comm_str {
+	char *str;
+	struct rb_node rb_node;
+	refcount_t refcnt;
+};
+
+/* Should perhaps be moved to struct machine */
+static struct rb_root comm_str_root;
+static struct rw_semaphore comm_str_lock = {.lock = PTHREAD_RWLOCK_INITIALIZER,};
+
+static struct comm_str *comm_str__get(struct comm_str *cs)
+{
+	if (cs && refcount_inc_not_zero(&cs->refcnt))
+		return cs;
+
+	return NULL;
+}
+
+static void comm_str__put(struct comm_str *cs)
+{
+	if (cs && refcount_dec_and_test(&cs->refcnt)) {
+		down_write(&comm_str_lock);
+		rb_erase(&cs->rb_node, &comm_str_root);
+		up_write(&comm_str_lock);
+		zfree(&cs->str);
+		free(cs);
+	}
+}
+
+static struct comm_str *comm_str__alloc(const char *str)
+{
+	struct comm_str *cs;
+
+	cs = zalloc(sizeof(*cs));
+	if (!cs)
+		return NULL;
+
+	cs->str = strdup(str);
+	if (!cs->str) {
+		free(cs);
+		return NULL;
+	}
+
+	refcount_set(&cs->refcnt, 1);
+
+	return cs;
+}
+
+static
+struct comm_str *__comm_str__findnew(const char *str, struct rb_root *root)
+{
+	struct rb_node **p = &root->rb_node;
+	struct rb_node *parent = NULL;
+	struct comm_str *iter, *new;
+	int cmp;
+
+	while (*p != NULL) {
+		parent = *p;
+		iter = rb_entry(parent, struct comm_str, rb_node);
+
+		/*
+		 * If we race with comm_str__put, iter->refcnt is 0
+		 * and it will be removed within comm_str__put call
+		 * shortly, ignore it in this search.
+		 */
+		cmp = strcmp(str, iter->str);
+		if (!cmp && comm_str__get(iter))
+			return iter;
+
+		if (cmp < 0)
+			p = &(*p)->rb_left;
+		else
+			p = &(*p)->rb_right;
+	}
+
+	new = comm_str__alloc(str);
+	if (!new)
+		return NULL;
+
+	rb_link_node(&new->rb_node, parent, p);
+	rb_insert_color(&new->rb_node, root);
+
+	return new;
+}
+
+static struct comm_str *comm_str__findnew(const char *str, struct rb_root *root)
+{
+	struct comm_str *cs;
+
+	down_write(&comm_str_lock);
+	cs = __comm_str__findnew(str, root);
+	up_write(&comm_str_lock);
+
+	return cs;
+}
+
+struct comm *comm__new(const char *str, u64 timestamp, bool exec)
+{
+	struct comm *comm = zalloc(sizeof(*comm));
+
+	if (!comm)
+		return NULL;
+
+	comm->start = timestamp;
+	comm->exec = exec;
+
+	comm->comm_str = comm_str__findnew(str, &comm_str_root);
+	if (!comm->comm_str) {
+		free(comm);
+		return NULL;
+	}
+
+	return comm;
+}
+
+int comm__override(struct comm *comm, const char *str, u64 timestamp, bool exec)
+{
+	struct comm_str *new, *old = comm->comm_str;
+
+	new = comm_str__findnew(str, &comm_str_root);
+	if (!new)
+		return -ENOMEM;
+
+	comm_str__put(old);
+	comm->comm_str = new;
+	comm->start = timestamp;
+	if (exec)
+		comm->exec = true;
+
+	return 0;
+}
+
+void comm__free(struct comm *comm)
+{
+	comm_str__put(comm->comm_str);
+	free(comm);
+}
+
+const char *comm__str(const struct comm *comm)
+{
+	return comm->comm_str->str;
+}