From 7eb2a8a1259043e107ebec94e30ed160a93f40a7 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Mon, 13 Nov 2017 15:08:49 +0100 Subject: [PATCH] unit: rework a bit how we keep the service fdstore from being destroyed during service restart When preparing for a restart we quickly go through the DEAD/INACTIVE service state before entering AUTO_RESTART. When doing this, we need to make sure we don't destroy the FD store. Previously this was done by checking the failure state of the unit, and keeping the FD store around when the unit failed, under the assumption that the restart logic will then get into action. This is not entirely correct howver, as there might be failure states that will no result in restarts. With this commit we slightly alter the logic: a ref counter for the fd store is added, that is increased right before we handle the restart logic, and decreased again right-after. This should ensure that the fdstore lives exactly as long as it needs. Follow-up for f0bfbfac43b7faa68ef1bb2ad659c191b9ec85d2. --- src/core/service.c | 23 ++++++++++++++++++----- src/core/service.h | 1 + src/core/unit.c | 12 ++++-------- src/core/unit.h | 5 ++--- 4 files changed, 25 insertions(+), 16 deletions(-) diff --git a/src/core/service.c b/src/core/service.c index ac3f14665d7..4b912fc3b9d 100644 --- a/src/core/service.c +++ b/src/core/service.c @@ -294,6 +294,9 @@ static void service_fd_store_unlink(ServiceFDStore *fs) { static void service_release_fd_store(Service *s) { assert(s); + if (s->n_keep_fd_store > 0) + return; + log_unit_debug(UNIT(s), "Releasing all stored fds"); while (s->fd_store) service_fd_store_unlink(s->fd_store); @@ -301,7 +304,7 @@ static void service_release_fd_store(Service *s) { assert(s->n_fd_store == 0); } -static void service_release_resources(Unit *u, bool inactive) { +static void service_release_resources(Unit *u) { Service *s = SERVICE(u); assert(s); @@ -315,8 +318,7 @@ static void service_release_resources(Unit *u, bool inactive) { s->stdout_fd = safe_close(s->stdout_fd); s->stderr_fd = safe_close(s->stderr_fd); - if (inactive) - service_release_fd_store(s); + service_release_fd_store(s); } static void service_done(Unit *u) { @@ -360,7 +362,7 @@ static void service_done(Unit *u) { s->timer_event_source = sd_event_source_unref(s->timer_event_source); - service_release_resources(u, true); + service_release_resources(u); } static int on_fd_store_io(sd_event_source *e, int fd, uint32_t revents, void *userdata) { @@ -1524,6 +1526,10 @@ static void service_enter_dead(Service *s, ServiceResult f, bool allow_restart) if (s->result != SERVICE_SUCCESS) log_unit_warning(UNIT(s), "Failed with result '%s'.", service_result_to_string(s->result)); + /* Make sure service_release_resources() doesn't destroy our FD store, while we are changing through + * SERVICE_FAILED/SERVICE_DEAD before entering into SERVICE_AUTO_RESTART. */ + s->n_keep_fd_store ++; + service_set_state(s, s->result != SERVICE_SUCCESS ? SERVICE_FAILED : SERVICE_DEAD); if (s->result != SERVICE_SUCCESS) @@ -1532,8 +1538,10 @@ static void service_enter_dead(Service *s, ServiceResult f, bool allow_restart) if (allow_restart && service_shall_restart(s)) { r = service_arm_timer(s, usec_add(now(CLOCK_MONOTONIC), s->restart_usec)); - if (r < 0) + if (r < 0) { + s->n_keep_fd_store--; goto fail; + } service_set_state(s, SERVICE_AUTO_RESTART); } else @@ -1541,6 +1549,11 @@ static void service_enter_dead(Service *s, ServiceResult f, bool allow_restart) * user can still introspect the counter. Do so on the next start. */ s->flush_n_restarts = true; + /* The new state is in effect, let's decrease the fd store ref counter again. Let's also readd us to the GC + * queue, so that the fd store is possibly gc'ed again */ + s->n_keep_fd_store--; + unit_add_to_gc_queue(UNIT(s)); + /* The next restart might not be a manual stop, hence reset the flag indicating manual stops */ s->forbid_restart = false; diff --git a/src/core/service.h b/src/core/service.h index 16b700637c2..236d37fcbc6 100644 --- a/src/core/service.h +++ b/src/core/service.h @@ -186,6 +186,7 @@ struct Service { ServiceFDStore *fd_store; unsigned n_fd_store; unsigned n_fd_store_max; + unsigned n_keep_fd_store; char *usb_function_descriptors; char *usb_function_strings; diff --git a/src/core/unit.c b/src/core/unit.c index 785bd5dc441..5c8dc4347ab 100644 --- a/src/core/unit.c +++ b/src/core/unit.c @@ -331,7 +331,6 @@ int unit_set_description(Unit *u, const char *description) { bool unit_check_gc(Unit *u) { UnitActiveState state; - bool inactive; assert(u); if (u->job) @@ -341,17 +340,14 @@ bool unit_check_gc(Unit *u) { return true; state = unit_active_state(u); - inactive = state == UNIT_INACTIVE; - /* If the unit is inactive and failed and no job is queued for - * it, then release its runtime resources */ + /* If the unit is inactive and failed and no job is queued for it, then release its runtime resources */ if (UNIT_IS_INACTIVE_OR_FAILED(state) && UNIT_VTABLE(u)->release_resources) - UNIT_VTABLE(u)->release_resources(u, inactive); + UNIT_VTABLE(u)->release_resources(u); - /* But we keep the unit object around for longer when it is - * referenced or configured to not be gc'ed */ - if (!inactive) + /* But we keep the unit object around for longer when it is referenced or configured to not be gc'ed */ + if (state != UNIT_INACTIVE) return true; if (u->perpetual) diff --git a/src/core/unit.h b/src/core/unit.h index adab6eb80f2..b0df341a03a 100644 --- a/src/core/unit.h +++ b/src/core/unit.h @@ -453,9 +453,8 @@ struct UnitVTable { * way */ bool (*check_gc)(Unit *u); - /* When the unit is not running and no job for it queued we - * shall release its runtime resources */ - void (*release_resources)(Unit *u, bool inactive); + /* When the unit is not running and no job for it queued we shall release its runtime resources */ + void (*release_resources)(Unit *u); /* Invoked on every child that died */ void (*sigchld_event)(Unit *u, pid_t pid, int code, int status); -- 2.47.3