On Tue, May 10, 2022 at 11:57:04AM +0200, Daniel Bristot de Oliveira wrote:
> +static int procfs_is_workload_pid(const char *comm_prefix, struct dirent *proc_entry)
> +{
> + char buffer[MAX_PATH];
> + int comm_fd, retval;
> + char *t_name;
> +
> + if (proc_entry->d_type != DT_DIR)
> + return 0;
> +
> + if (*proc_entry->d_name == '.')
> + return 0;
> +
> + /* check if the string is a pid */
> + for (t_name = proc_entry->d_name; t_name; t_name++) {
> + if (!isdigit(*t_name))
> + break;
> + }
> +
> + if (*t_name != '\0')
> + return 0;
> +
> + snprintf(buffer, MAX_PATH, "/proc/%s/comm", proc_entry->d_name);
> + comm_fd = open(buffer, O_RDONLY);
> + if (comm_fd < 0)
> + return 0;
> +
> + memset(buffer, 0, MAX_PATH);
> + retval = read(comm_fd, buffer, MAX_PATH);
> +
> + close(comm_fd);
> +
> + if (retval <= 0)
> + return 0;
> +
> + retval = strncmp(comm_prefix, buffer, strlen(comm_prefix));
> + if (retval)
> + return 0;
> +
> + /* comm already have \n */
> + debug_msg("Found workload pid:%s comm:%s", proc_entry->d_name, buffer);
> +
> + return 1;
> +}
> +
> +/*
> + * set_comm_sched_attr - set sched params to threads starting with char *comm_prefix
> + *
> + * This function uses /procfs to list the currently running threads and then set the
> + * sched_attr *attr to the threads that start with char *comm_prefix. It is
> * mainly used to set the priority to the kernel threads created by the
> * tracers.
> */
> -int set_comm_sched_attr(const char *comm, struct sched_attr *attr)
> +int set_comm_sched_attr(const char *comm_prefix, struct sched_attr *attr)
> {
> - int flags = PROC_FILLCOM | PROC_FILLSTAT;
> - PROCTAB *ptp;
> - proc_t task;
> + struct dirent *proc_entry;
> + DIR *procfs;
> int retval;
>
> - ptp = openproc(flags);
> - if (!ptp) {
> - err_msg("error openproc()\n");
> - return -ENOENT;
> + if (strlen(comm_prefix) >= MAX_PATH) {
> + err_msg("Command prefix is too long: %d < strlen(%s)\n",
> + MAX_PATH, comm_prefix);
> + exit(EINVAL);
> }
>
> - memset(&task, 0, sizeof(task));
> + procfs = opendir("/proc");
Maybe you want to check if procfs is a valid handle before using it.
> +
> + while ((proc_entry = readdir(procfs))) {
>
> - while (readproc(ptp, &task)) {
> - retval = strncmp(comm, task.cmd, strlen(comm));
> - if (retval)
> + retval = procfs_is_workload_pid(comm_prefix, proc_entry);
> + if (!retval)
> continue;
> - retval = __set_sched_attr(task.tid, attr);
> - if (retval)
> +
> + /* procfs_is_workload_pid confirmed it is a pid */
> + retval = __set_sched_attr(atoi(proc_entry->d_name), attr);
> + if (retval) {
> + err_msg("Error setting sched attributes for pid:%s\n", proc_entry->d_name);
> goto out_err;
> - }
> + }
>
> - closeproc(ptp);
> + debug_msg("Set sched attributes for pid:%s\n", proc_entry->d_name);
> + }
> return 0;
>
> out_err:
> - closeproc(ptp);
> + closedir(procfs);
> return 1;
> }
>
> diff --git a/tools/tracing/rtla/src/utils.h b/tools/tracing/rtla/src/utils.h
> index fa08e374870a..5571afd3b549 100644
> --- a/tools/tracing/rtla/src/utils.h
> +++ b/tools/tracing/rtla/src/utils.h
> @@ -6,6 +6,7 @@
> * '18446744073709551615\0'
> */
> #define BUFF_U64_STR_SIZE 24
> +#define MAX_PATH 1024
linux/limits.h defined MAX_PATH as well, though as 4096. Maybe use that
definition? If you want to make it dynamic you could use fpathconf(fd,
_PC_PATH_MAX) but one could argue that is over engineering :)
Thanks for the fix. Anyway just nitpicking.
Reviewed-by: Daniel Wagner <dwagner@xxxxxxx>
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