diff options
Diffstat (limited to 'src/shared')
| -rw-r--r-- | src/shared/common-signal.c | 94 | ||||
| -rw-r--r-- | src/shared/common-signal.h | 58 | ||||
| -rw-r--r-- | src/shared/meson.build | 1 |
3 files changed, 153 insertions, 0 deletions
diff --git a/src/shared/common-signal.c b/src/shared/common-signal.c new file mode 100644 index 0000000000..1896443632 --- /dev/null +++ b/src/shared/common-signal.c @@ -0,0 +1,94 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include "common-signal.h" +#include "fd-util.h" +#include "fileio.h" +#include "process-util.h" +#include "signal-util.h" + +int sigrtmin18_handler(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) { + struct sigrtmin18_info *info = userdata; + _cleanup_free_ char *comm = NULL; + int r; + + assert(s); + assert(si); + + (void) get_process_comm(si->ssi_pid, &comm); + + if (si->ssi_code != SI_QUEUE) { + log_notice("Received control signal %s from process " PID_FMT " (%s) without command value, ignoring.", + signal_to_string(si->ssi_signo), + (pid_t) si->ssi_pid, + strna(comm)); + return 0; + } + + log_debug("Received control signal %s from process " PID_FMT " (%s) with command 0x%08x.", + signal_to_string(si->ssi_signo), + (pid_t) si->ssi_pid, + strna(comm), + (unsigned) si->ssi_int); + + switch (si->ssi_int) { + + case _COMMON_SIGNAL_COMMAND_LOG_LEVEL_BASE..._COMMON_SIGNAL_COMMAND_LOG_LEVEL_END: + log_set_max_level(si->ssi_int - _COMMON_SIGNAL_COMMAND_LOG_LEVEL_BASE); + break; + + case COMMON_SIGNAL_COMMAND_CONSOLE: + log_set_target_and_open(LOG_TARGET_CONSOLE); + break; + case COMMON_SIGNAL_COMMAND_JOURNAL: + log_set_target_and_open(LOG_TARGET_JOURNAL); + break; + case COMMON_SIGNAL_COMMAND_KMSG: + log_set_target_and_open(LOG_TARGET_KMSG); + break; + case COMMON_SIGNAL_COMMAND_NULL: + log_set_target_and_open(LOG_TARGET_NULL); + break; + + case COMMON_SIGNAL_COMMAND_MEMORY_PRESSURE: + if (info && info->memory_pressure_handler) + return info->memory_pressure_handler(s, info->memory_pressure_userdata); + + sd_event_trim_memory(); + break; + + case COMMON_SIGNAL_COMMAND_MALLOC_INFO: { + _cleanup_free_ char *data = NULL; + _cleanup_fclose_ FILE *f = NULL; + size_t sz; + + f = open_memstream_unlocked(&data, &sz); + if (!f) { + log_oom(); + break; + } + + if (malloc_info(0, f) < 0) { + log_error_errno(errno, "Failed to invoke malloc_info(): %m"); + break; + } + + fputc(0, f); + + r = fflush_and_check(f); + if (r < 0) { + log_error_errno(r, "Failed to flush malloc_info() buffer: %m"); + break; + } + + log_dump(LOG_INFO, data); + break; + } + + default: + log_notice("Received control signal %s with unknown command 0x%08x, ignoring.", + signal_to_string(si->ssi_signo), (unsigned) si->ssi_int); + break; + } + + return 0; +} diff --git a/src/shared/common-signal.h b/src/shared/common-signal.h new file mode 100644 index 0000000000..7d2ab28f51 --- /dev/null +++ b/src/shared/common-signal.h @@ -0,0 +1,58 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <syslog.h> + +#include <sd-event.h> + +/* All our long-running services should implement a SIGRTMIN+18 handler that can be used to trigger certain + * actions that affect service runtime. The specific action is indicated via the "value integer" you can pass + * along realtime signals. This is mostly intended for debugging purposes and is entirely asynchronous in + * nature. Specifically, these are the commands: + * + * Currently available operations: + * + * • Change maximum log level + * • Change log target + * • Invoke memory trimming, like under memory pressure + * • Write glibc malloc() allocation info to logs + * + * How to use this? Via a command like the following: + * + * /usr/bin/kill -s RTMIN+18 -q 768 1 + * + * (This will tell PID 1 to trim its memory use.) + * + * or: + * + * systemctl kill --kill-value=0x300 -s RTMIN+18 systemd-journald + * + * (This will tell journald to trim its memory use.) + */ + +enum { + _COMMON_SIGNAL_COMMAND_LOG_LEVEL_BASE = 0x100, + COMMON_SIGNAL_COMMAND_LOG_EMERG = _COMMON_SIGNAL_COMMAND_LOG_LEVEL_BASE + LOG_EMERG, + COMMON_SIGNAL_COMMAND_LOG_ALERT = _COMMON_SIGNAL_COMMAND_LOG_LEVEL_BASE + LOG_ALERT, + COMMON_SIGNAL_COMMAND_LOG_CRIT = _COMMON_SIGNAL_COMMAND_LOG_LEVEL_BASE + LOG_CRIT, + COMMON_SIGNAL_COMMAND_LOG_ERR = _COMMON_SIGNAL_COMMAND_LOG_LEVEL_BASE + LOG_ERR, + COMMON_SIGNAL_COMMAND_LOG_WARNING = _COMMON_SIGNAL_COMMAND_LOG_LEVEL_BASE + LOG_WARNING, + COMMON_SIGNAL_COMMAND_LOG_NOTICE = _COMMON_SIGNAL_COMMAND_LOG_LEVEL_BASE + LOG_NOTICE, + COMMON_SIGNAL_COMMAND_LOG_INFO = _COMMON_SIGNAL_COMMAND_LOG_LEVEL_BASE + LOG_INFO, + COMMON_SIGNAL_COMMAND_LOG_DEBUG = _COMMON_SIGNAL_COMMAND_LOG_LEVEL_BASE + LOG_DEBUG, + _COMMON_SIGNAL_COMMAND_LOG_LEVEL_END = COMMON_SIGNAL_COMMAND_LOG_DEBUG, + + COMMON_SIGNAL_COMMAND_CONSOLE = 0x200, + COMMON_SIGNAL_COMMAND_JOURNAL, + COMMON_SIGNAL_COMMAND_KMSG, + COMMON_SIGNAL_COMMAND_NULL, + + COMMON_SIGNAL_COMMAND_MEMORY_PRESSURE = 0x300, + COMMON_SIGNAL_COMMAND_MALLOC_INFO, +}; + +struct sigrtmin18_info { + sd_event_handler_t memory_pressure_handler; + void *memory_pressure_userdata; +}; + +int sigrtmin18_handler(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata); diff --git a/src/shared/meson.build b/src/shared/meson.build index d8a688b275..82fd206d69 100644 --- a/src/shared/meson.build +++ b/src/shared/meson.build @@ -35,6 +35,7 @@ shared_sources = files( 'chown-recursive.c', 'clean-ipc.c', 'clock-util.c', + 'common-signal.c', 'compare-operator.c', 'condition.c', 'conf-parser.c', |