diff options
| -rw-r--r-- | priod.c | 190 |
1 files changed, 171 insertions, 19 deletions
@@ -2,6 +2,7 @@ * priod.c: process reprioritizing daemon * * Thanks to http://netsplit.com/the-proc-connector-and-socket-filters + * for showing the way around the proc connector and BPF. * * Copyright (c) 2017, Přemysl Janouch <p.janouch@gmail.com> * @@ -27,6 +28,8 @@ #define PROGRAM_NAME "priod" #include "liberty/liberty.c" +#include <dirent.h> + #include <linux/cn_proc.h> #include <linux/netlink.h> #include <linux/connector.h> @@ -37,6 +40,17 @@ // --- Main program ------------------------------------------------------------ +#define RULE_UNSET INT_MIN + +struct rule +{ + char *program_name; ///< Program name to match against + + int oom_score_adj; ///< For /proc/%/oom_score_adj + int prio; ///< For setpriority() + int ioprio; ///< For SYS_ioprio_set +}; + struct app_context { struct poller poller; ///< Poller @@ -44,6 +58,9 @@ struct app_context int proc_fd; ///< Proc connector FD struct poller_fd proc_event; ///< Proc connector read event + + struct rule *rules; ///< Rules + size_t rules_len; ///< Number of rules }; // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - @@ -61,6 +78,77 @@ log_message_custom (void *user_data, const char *quote, const char *fmt, fputs ("\n", stream); } +// --- Configuration ----------------------------------------------------------- + +static bool +load_integer (struct str_map *root, const char *key, int min, int max, + int *value, struct error **e) +{ + *value = RULE_UNSET; + + struct config_item *item; + if (!(item = str_map_find (root, key))) + return true; + + if (item->type != CONFIG_ITEM_INTEGER + || item->value.integer < min || item->value.integer > max) + return error_set (e, "%s: must be an integer (%d..%d)", key, min, max); + + *value = item->value.integer; + return true; +} + +static bool +load_rule (const char *name, struct str_map *m, struct rule *r, + struct error **e) +{ + r->program_name = xstrdup (name); + if (!load_integer (m, "oom_score_adj", -1000, 1000, &r->oom_score_adj, e) + || !load_integer (m, "prio", -20, 19, &r->prio, e) + || !load_integer (m, "ioprio", 0, 7, &r->ioprio, e)) + return false; + return true; +} + +static struct rule * +find_rule (struct app_context *ctx, const char *program_name) +{ + for (size_t i = 0; i < ctx->rules_len; i++) + if (!strcmp (ctx->rules[i].program_name, program_name)) + return ctx->rules + i; + return NULL; +} + +static void +load_configuration (struct app_context *ctx, const char *config_path) +{ + struct error *e = NULL; + struct config_item *root = config_read_from_file (config_path, &e); + + if (e) + { + print_error ("error loading configuration: %s", e->message); + error_free (e); + exit (EXIT_FAILURE); + } + + struct str_map_iter iter; + str_map_iter_init (&iter, &root->value.object); + ctx->rules = xcalloc (iter.map->len, sizeof *ctx->rules); + ctx->rules_len = 0; + + struct config_item *subtree; + while ((subtree = str_map_iter_next (&iter))) + { + const char *path = iter.link->key; + if (subtree->type != CONFIG_ITEM_OBJECT) + exit_fatal ("rule `%s' in configuration is not an object", path); + if (!load_rule (path, &subtree->value.object, + &ctx->rules[ctx->rules_len++], &e)) + exit_fatal ("rule `%s': %s", path, e->message); + } +} + // --- Signals ----------------------------------------------------------------- static int g_signal_pipe[2]; ///< A pipe used to signal... signals @@ -125,35 +213,95 @@ enum #define IOPRIO_CLASS_SHIFT 13 static void -on_exec_name (struct app_context *ctx, int pid, const char *name) +adj_oom_score (int pid, const char *program_name, int score) { - print_status ("exec %d %s", pid, name); - - if (true) - return; - - setpriority (PRIO_PROCESS, pid, 0 /* TODO -20..20 */); - - // TODO: this is per thread, and there's an inherent race condition; - // keep going through /proc/%d/task and reprioritize all threads; - // stop trying after N-th try - syscall (SYS_ioprio_set, IOPRIO_WHO_PROCESS, - IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT | 0 /* TODO 0..7 */); - + char buf[16]; snprintf (buf, sizeof buf, "%d\n", score); char *path = xstrdup_printf ("/proc/%d/oom_score_adj", pid); struct error *e = NULL; - // TODO: figure out the contents - if (!write_file (path, "", 0, &e)) + if (!write_file (path, buf, strlen (buf), &e)) { - print_error ("%s", e->message); + print_error ("%d (%s): %s", pid, program_name, e->message); error_free (e); } free (path); } +static bool +reprioritize (int pid, const char *program_name, DIR *dir, struct rule *rule, + struct str_map *set) +{ + size_t not_previously_visited = 0; + struct dirent *iter; + while ((errno = 0, iter = readdir (dir))) + { + int tid = atoi (iter->d_name); + if (!tid || str_map_find (set, iter->d_name)) + continue; + + print_debug (" - thread %d", tid); + str_map_set (set, iter->d_name, (void *) ++not_previously_visited); + + if (RULE_UNSET != rule->prio + && setpriority (PRIO_PROCESS, pid, rule->prio)) + print_error ("%d (%s): thread %d: setpriority: %s", + pid, program_name, tid, strerror (errno)); + if (RULE_UNSET != rule->ioprio + && syscall (SYS_ioprio_set, IOPRIO_WHO_PROCESS, tid, + IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT | rule->ioprio)) + print_error ("%d (%s): thread %d: ioprio_set: %s", + pid, program_name, tid, strerror (errno)); + } + if (errno) + { + print_error ("%d (%s): readdir: %s", + pid, program_name, strerror (errno)); + } + return not_previously_visited == 0; +} + +static void +on_exec_name (struct app_context *ctx, int pid, const char *program_name) +{ + // TODO: we might want to at least provide more criteria to match on, + // so as to not blindly trust everything, despite these priorities being + // relatively harmless if you overlook possible "denial of service" + struct rule *rule = find_rule (ctx, program_name); + const char *slash = strrchr (program_name, '/'); + if (!rule && (!slash || !(rule = find_rule (ctx, slash + 1)))) + return; + + print_debug ("%d (%s) matched", pid, program_name); + if (RULE_UNSET != rule->oom_score_adj) + adj_oom_score (pid, program_name, rule->oom_score_adj); + + // Priority APIs are strictly per-thread (i.e. Linux "task"), so we must + // iterate through all tasks within a thread group + char *path = xstrdup_printf ("/proc/%d/task", pid); + DIR *dir = opendir (path); + free (path); + if (!dir) + { + print_error ("%d (%s): opendir: %s", + pid, program_name, strerror (errno)); + return; + } + + struct str_map set; + str_map_init (&set); + + // This has an inherent race condition, but let's give it a try + for (size_t retries = 3; retries--; ) + if (reprioritize (pid, program_name, dir, rule, &set)) + break; + + str_map_free (&set); + closedir (dir); +} + static void on_exec (struct app_context *ctx, int pid) { + // This is inherently racy but there seems to be no better way to do it char *path = xstrdup_printf ("/proc/%d/cmdline", pid); struct str cmdline; str_init (&cmdline); @@ -240,7 +388,8 @@ parse_program_arguments (int argc, char **argv) }; struct opt_handler oh; - opt_handler_init (&oh, argc, argv, opts, "CONFIG", "Fan controller."); + opt_handler_init (&oh, argc, argv, opts, "CONFIG", + "Process reprioritizing daemon."); int c; while ((c = opt_handler_get (&oh)) != -1) @@ -334,7 +483,7 @@ main (int argc, char *argv[]) signal_event.user_data = &ctx; poller_fd_set (&signal_event, POLLIN); - // TODO: load configuration so that we know what to do with the events + load_configuration (&ctx, config_path); ctx.proc_fd = socket (PF_NETLINK, SOCK_DGRAM | SOCK_NONBLOCK | SOCK_CLOEXEC, NETLINK_CONNECTOR); @@ -379,5 +528,8 @@ main (int argc, char *argv[]) poller_free (&ctx.poller); xclose (ctx.proc_fd); + for (size_t i = 0; i < ctx.rules_len; i++) + free (ctx.rules[i].program_name); + free (ctx.rules); return EXIT_SUCCESS; } |