priod: finish basic operation
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7713850987
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B715679E3A361BE6
190
priod.c
190
priod.c
@ -2,6 +2,7 @@
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* priod.c: process reprioritizing daemon
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*
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* Thanks to http://netsplit.com/the-proc-connector-and-socket-filters
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* for showing the way around the proc connector and BPF.
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*
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* Copyright (c) 2017, Přemysl Janouch <p.janouch@gmail.com>
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*
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@ -27,6 +28,8 @@
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#define PROGRAM_NAME "priod"
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#include "liberty/liberty.c"
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#include <dirent.h>
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#include <linux/cn_proc.h>
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#include <linux/netlink.h>
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#include <linux/connector.h>
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@ -37,6 +40,17 @@
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// --- Main program ------------------------------------------------------------
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#define RULE_UNSET INT_MIN
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struct rule
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{
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char *program_name; ///< Program name to match against
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int oom_score_adj; ///< For /proc/%/oom_score_adj
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int prio; ///< For setpriority()
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int ioprio; ///< For SYS_ioprio_set
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};
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struct app_context
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{
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struct poller poller; ///< Poller
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@ -44,6 +58,9 @@ struct app_context
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int proc_fd; ///< Proc connector FD
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struct poller_fd proc_event; ///< Proc connector read event
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struct rule *rules; ///< Rules
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size_t rules_len; ///< Number of rules
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};
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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@ -61,6 +78,77 @@ log_message_custom (void *user_data, const char *quote, const char *fmt,
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fputs ("\n", stream);
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}
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// --- Configuration -----------------------------------------------------------
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static bool
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load_integer (struct str_map *root, const char *key, int min, int max,
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int *value, struct error **e)
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{
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*value = RULE_UNSET;
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struct config_item *item;
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if (!(item = str_map_find (root, key)))
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return true;
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if (item->type != CONFIG_ITEM_INTEGER
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|| item->value.integer < min || item->value.integer > max)
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return error_set (e, "%s: must be an integer (%d..%d)", key, min, max);
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*value = item->value.integer;
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return true;
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}
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static bool
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load_rule (const char *name, struct str_map *m, struct rule *r,
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struct error **e)
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{
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r->program_name = xstrdup (name);
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if (!load_integer (m, "oom_score_adj", -1000, 1000, &r->oom_score_adj, e)
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|| !load_integer (m, "prio", -20, 19, &r->prio, e)
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|| !load_integer (m, "ioprio", 0, 7, &r->ioprio, e))
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return false;
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return true;
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}
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static struct rule *
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find_rule (struct app_context *ctx, const char *program_name)
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{
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for (size_t i = 0; i < ctx->rules_len; i++)
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if (!strcmp (ctx->rules[i].program_name, program_name))
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return ctx->rules + i;
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return NULL;
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}
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static void
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load_configuration (struct app_context *ctx, const char *config_path)
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{
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struct error *e = NULL;
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struct config_item *root = config_read_from_file (config_path, &e);
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if (e)
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{
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print_error ("error loading configuration: %s", e->message);
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error_free (e);
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exit (EXIT_FAILURE);
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}
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struct str_map_iter iter;
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str_map_iter_init (&iter, &root->value.object);
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ctx->rules = xcalloc (iter.map->len, sizeof *ctx->rules);
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ctx->rules_len = 0;
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struct config_item *subtree;
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while ((subtree = str_map_iter_next (&iter)))
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{
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const char *path = iter.link->key;
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if (subtree->type != CONFIG_ITEM_OBJECT)
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exit_fatal ("rule `%s' in configuration is not an object", path);
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if (!load_rule (path, &subtree->value.object,
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&ctx->rules[ctx->rules_len++], &e))
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exit_fatal ("rule `%s': %s", path, e->message);
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}
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}
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// --- Signals -----------------------------------------------------------------
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static int g_signal_pipe[2]; ///< A pipe used to signal... signals
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@ -125,35 +213,95 @@ enum
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#define IOPRIO_CLASS_SHIFT 13
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static void
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on_exec_name (struct app_context *ctx, int pid, const char *name)
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adj_oom_score (int pid, const char *program_name, int score)
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{
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print_status ("exec %d %s", pid, name);
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if (true)
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return;
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setpriority (PRIO_PROCESS, pid, 0 /* TODO -20..20 */);
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// TODO: this is per thread, and there's an inherent race condition;
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// keep going through /proc/%d/task and reprioritize all threads;
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// stop trying after N-th try
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syscall (SYS_ioprio_set, IOPRIO_WHO_PROCESS,
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IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT | 0 /* TODO 0..7 */);
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char buf[16]; snprintf (buf, sizeof buf, "%d\n", score);
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char *path = xstrdup_printf ("/proc/%d/oom_score_adj", pid);
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struct error *e = NULL;
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// TODO: figure out the contents
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if (!write_file (path, "", 0, &e))
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if (!write_file (path, buf, strlen (buf), &e))
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{
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print_error ("%s", e->message);
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print_error ("%d (%s): %s", pid, program_name, e->message);
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error_free (e);
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}
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free (path);
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}
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static bool
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reprioritize (int pid, const char *program_name, DIR *dir, struct rule *rule,
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struct str_map *set)
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{
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size_t not_previously_visited = 0;
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struct dirent *iter;
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while ((errno = 0, iter = readdir (dir)))
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{
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int tid = atoi (iter->d_name);
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if (!tid || str_map_find (set, iter->d_name))
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continue;
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print_debug (" - thread %d", tid);
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str_map_set (set, iter->d_name, (void *) ++not_previously_visited);
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if (RULE_UNSET != rule->prio
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&& setpriority (PRIO_PROCESS, pid, rule->prio))
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print_error ("%d (%s): thread %d: setpriority: %s",
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pid, program_name, tid, strerror (errno));
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if (RULE_UNSET != rule->ioprio
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&& syscall (SYS_ioprio_set, IOPRIO_WHO_PROCESS, tid,
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IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT | rule->ioprio))
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print_error ("%d (%s): thread %d: ioprio_set: %s",
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pid, program_name, tid, strerror (errno));
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}
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if (errno)
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{
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print_error ("%d (%s): readdir: %s",
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pid, program_name, strerror (errno));
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}
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return not_previously_visited == 0;
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}
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static void
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on_exec_name (struct app_context *ctx, int pid, const char *program_name)
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{
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// TODO: we might want to at least provide more criteria to match on,
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// so as to not blindly trust everything, despite these priorities being
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// relatively harmless if you overlook possible "denial of service"
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struct rule *rule = find_rule (ctx, program_name);
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const char *slash = strrchr (program_name, '/');
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if (!rule && (!slash || !(rule = find_rule (ctx, slash + 1))))
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return;
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print_debug ("%d (%s) matched", pid, program_name);
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if (RULE_UNSET != rule->oom_score_adj)
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adj_oom_score (pid, program_name, rule->oom_score_adj);
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// Priority APIs are strictly per-thread (i.e. Linux "task"), so we must
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// iterate through all tasks within a thread group
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char *path = xstrdup_printf ("/proc/%d/task", pid);
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DIR *dir = opendir (path);
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free (path);
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if (!dir)
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{
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print_error ("%d (%s): opendir: %s",
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pid, program_name, strerror (errno));
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return;
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}
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struct str_map set;
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str_map_init (&set);
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// This has an inherent race condition, but let's give it a try
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for (size_t retries = 3; retries--; )
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if (reprioritize (pid, program_name, dir, rule, &set))
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break;
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str_map_free (&set);
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closedir (dir);
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}
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static void
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on_exec (struct app_context *ctx, int pid)
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{
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// This is inherently racy but there seems to be no better way to do it
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char *path = xstrdup_printf ("/proc/%d/cmdline", pid);
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struct str cmdline;
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str_init (&cmdline);
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@ -240,7 +388,8 @@ parse_program_arguments (int argc, char **argv)
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};
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struct opt_handler oh;
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opt_handler_init (&oh, argc, argv, opts, "CONFIG", "Fan controller.");
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opt_handler_init (&oh, argc, argv, opts, "CONFIG",
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"Process reprioritizing daemon.");
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int c;
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while ((c = opt_handler_get (&oh)) != -1)
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@ -334,7 +483,7 @@ main (int argc, char *argv[])
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signal_event.user_data = &ctx;
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poller_fd_set (&signal_event, POLLIN);
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// TODO: load configuration so that we know what to do with the events
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load_configuration (&ctx, config_path);
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ctx.proc_fd = socket (PF_NETLINK,
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SOCK_DGRAM | SOCK_NONBLOCK | SOCK_CLOEXEC, NETLINK_CONNECTOR);
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@ -379,5 +528,8 @@ main (int argc, char *argv[])
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poller_free (&ctx.poller);
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xclose (ctx.proc_fd);
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for (size_t i = 0; i < ctx.rules_len; i++)
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free (ctx.rules[i].program_name);
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free (ctx.rules);
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return EXIT_SUCCESS;
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}
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