tools/rtla: Deduplicate cgroup path opening code

Both set_pid_cgroup() and set_comm_cgroup() functions contain
identical code for opening the cgroup.procs file.

Extract this common code into a new helper function open_cgroup_procs()
to reduce code duplication and improve maintainability.

Signed-off-by: Costa Shulyupin <costa.shul@redhat.com>
Link: https://lore.kernel.org/r/20251224125058.1771519-1-costa.shul@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>

diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c
index 9cf5a0098e9aa9278cb620ce963dc7338a5bd22f..0b84e02b13df3a74e6182aeb6fd682c932981319 100644 (file)
--- a/tools/tracing/rtla/src/utils.c
+++ b/tools/tracing/rtla/src/utils.c
@@ -784,27 +784,27 @@ static int get_self_cgroup(char *self_cg, int sizeof_self_cg)
 }
 
 /*
- * set_comm_cgroup - Set cgroup to pid_t pid
+ * open_cgroup_procs - Open the cgroup.procs file for the given cgroup
  *
- * If cgroup argument is not NULL, the threads will move to the given cgroup.
- * Otherwise, the cgroup of the calling, i.e., rtla, thread will be used.
+ * If cgroup argument is not NULL, the cgroup.procs file for that cgroup
+ * will be opened. Otherwise, the cgroup of the calling, i.e., rtla, thread
+ * will be used.
  *
  * Supports cgroup v2.
  *
- * Returns 1 on success, 0 otherwise.
+ * Returns the file descriptor on success, -1 otherwise.
  */
-int set_pid_cgroup(pid_t pid, const char *cgroup)
+static int open_cgroup_procs(const char *cgroup)
 {
        char cgroup_path[MAX_PATH - strlen("/cgroup.procs")];
        char cgroup_procs[MAX_PATH];
-       char pid_str[24];
        int retval;
        int cg_fd;
 
        retval = find_mount("cgroup2", cgroup_path, sizeof(cgroup_path));
        if (!retval) {
                err_msg("Did not find cgroupv2 mount point\n");
-               return 0;
+               return -1;
        }
 
        if (!cgroup) {
@@ -812,7 +812,7 @@ int set_pid_cgroup(pid_t pid, const char *cgroup)
                                sizeof(cgroup_path) - strlen(cgroup_path));
                if (!retval) {
                        err_msg("Did not find self cgroup\n");
-                       return 0;
+                       return -1;
                }
        } else {
                snprintf(&cgroup_path[strlen(cgroup_path)],
@@ -824,6 +824,29 @@ int set_pid_cgroup(pid_t pid, const char *cgroup)
        debug_msg("Using cgroup path at: %s\n", cgroup_procs);
 
        cg_fd = open(cgroup_procs, O_RDWR);
+       if (cg_fd < 0)
+               return -1;
+
+       return cg_fd;
+}
+
+/*
+ * set_pid_cgroup - Set cgroup to pid_t pid
+ *
+ * If cgroup argument is not NULL, the threads will move to the given cgroup.
+ * Otherwise, the cgroup of the calling, i.e., rtla, thread will be used.
+ *
+ * Supports cgroup v2.
+ *
+ * Returns 1 on success, 0 otherwise.
+ */
+int set_pid_cgroup(pid_t pid, const char *cgroup)
+{
+       char pid_str[24];
+       int retval;
+       int cg_fd;
+
+       cg_fd = open_cgroup_procs(cgroup);
        if (cg_fd < 0)
                return 0;
 
@@ -853,8 +876,6 @@ int set_pid_cgroup(pid_t pid, const char *cgroup)
  */
 int set_comm_cgroup(const char *comm_prefix, const char *cgroup)
 {
-       char cgroup_path[MAX_PATH - strlen("/cgroup.procs")];
-       char cgroup_procs[MAX_PATH];
        struct dirent *proc_entry;
        DIR *procfs;
        int retval;
@@ -866,29 +887,7 @@ int set_comm_cgroup(const char *comm_prefix, const char *cgroup)
                return 0;
        }
 
-       retval = find_mount("cgroup2", cgroup_path, sizeof(cgroup_path));
-       if (!retval) {
-               err_msg("Did not find cgroupv2 mount point\n");
-               return 0;
-       }
-
-       if (!cgroup) {
-               retval = get_self_cgroup(&cgroup_path[strlen(cgroup_path)],
-                               sizeof(cgroup_path) - strlen(cgroup_path));
-               if (!retval) {
-                       err_msg("Did not find self cgroup\n");
-                       return 0;
-               }
-       } else {
-               snprintf(&cgroup_path[strlen(cgroup_path)],
-                               sizeof(cgroup_path) - strlen(cgroup_path), "%s/", cgroup);
-       }
-
-       snprintf(cgroup_procs, MAX_PATH, "%s/cgroup.procs", cgroup_path);
-
-       debug_msg("Using cgroup path at: %s\n", cgroup_procs);
-
-       cg_fd = open(cgroup_procs, O_RDWR);
+       cg_fd = open_cgroup_procs(cgroup);
        if (cg_fd < 0)
                return 0;