From f173657bccae4dd0cbfe0a7ed33ebc9117b74f05 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Wed, 24 Jul 2013 07:24:05 +0200 Subject: [PATCH] core: synchronously block when logging Previously, the logging sockets were asynchronous and if clogged we'd lose messages. We did this to be extra careful given that PID 1 might need to spawn the logging daemon as response to PID 1's own log messages and we really should avoid a deadlock in that case. As it turns out this causes loss of too many messages, hence make the socket blocking again, however put a time limit on it to avoid unbounded deadlocks in the unlikely case they happen. https://bugs.freedesktop.org/show_bug.cgi?id=66664 --- src/shared/log.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/src/shared/log.c b/src/shared/log.c index 27317f7..8f4995a 100644 --- a/src/shared/log.c +++ b/src/shared/log.c @@ -115,16 +115,20 @@ void log_close_syslog(void) { static int create_log_socket(int type) { int fd; + struct timeval tv; - /* All output to the syslog/journal fds we do asynchronously, - * and if the buffers are full we just drop the messages */ - - fd = socket(AF_UNIX, type|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); + fd = socket(AF_UNIX, type|SOCK_CLOEXEC, 0); if (fd < 0) return -errno; fd_inc_sndbuf(fd, SNDBUF_SIZE); + /* We need a blocking fd here since we'd otherwise lose + messages way too early. However, let's not hang forever in the + unlikely case of a deadlock. */ + timeval_store(&tv, 1*USEC_PER_MINUTE); + setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)); + return fd; }