From 67962036f6c6cfd34828c1f1f1fbdc0018fb9898 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= Date: Tue, 23 Apr 2019 15:24:56 +0200 Subject: [PATCH] basic/socket-util: put a limit on the loop to flush connections Follow-up for #12346. --- src/basic/socket-util.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/src/basic/socket-util.c b/src/basic/socket-util.c index cf2e08c2df8..32a0d9c5d06 100644 --- a/src/basic/socket-util.c +++ b/src/basic/socket-util.c @@ -1219,6 +1219,10 @@ ssize_t next_datagram_size_fd(int fd) { return (ssize_t) k; } +/* Put a limit on how many times will attempt to call accept4(). We loop + * only on "transient" errors, but let's make sure we don't loop forever. */ +#define MAX_FLUSH_ITERATIONS 1024 + int flush_accept(int fd) { struct pollfd pollfd = { @@ -1242,7 +1246,7 @@ int flush_accept(int fd) { * we can loop safely on transient errors below. */ return -ENOTTY; - for (;;) { + for (unsigned iteration = 0;; iteration++) { int cfd; r = poll(&pollfd, 1, 0); @@ -1255,6 +1259,10 @@ int flush_accept(int fd) { if (r == 0) return 0; + if (iteration >= MAX_FLUSH_ITERATIONS) + return log_debug_errno(SYNTHETIC_ERRNO(EBUSY), + "Failed to flush connections within " STRINGIFY(MAX_FLUSH_ITERATIONS) " iterations."); + cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC); if (cfd < 0) { if (errno == EAGAIN)