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From 80b37e95f732ab5de22fda0d8d14c7d58ac29877 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
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Date: Sun, 12 Jan 2014 11:38:56 -0500
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Subject: [PATCH] core: do not segfault if swap activity happens when
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/proc/swaps is not open
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In https://bugzilla.redhat.com/show_bug.cgi?id=969795 systemd crashes
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in swap_dispatch_reload called from manager_loop becuase m->proc_swaps
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is NULL. It can legitimately be NULL if something went wrong when
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initially enumerating swap devices when starting the manager. This
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is probably a sign of significant trouble, but let's do our best
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to recover.
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---
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src/core/swap.c | 45 +++++++++++++++++++++++++++++----------------
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1 file changed, 29 insertions(+), 16 deletions(-)
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diff --git a/src/core/swap.c b/src/core/swap.c
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index 147f710..f295b65 100644
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--- a/src/core/swap.c
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+++ b/src/core/swap.c
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@@ -1068,14 +1068,40 @@ static int swap_load_proc_swaps(Manager *m, bool set_flags) {
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return r;
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}
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+static int open_proc_swaps(Manager *m) {
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+ if (!m->proc_swaps) {
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+ struct epoll_event ev = {
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+ .events = EPOLLPRI,
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+ .data.ptr = &m->swap_watch,
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+ };
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+
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+ m->proc_swaps = fopen("/proc/swaps", "re");
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+ if (!m->proc_swaps)
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+ return (errno == ENOENT) ? 0 : -errno;
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+
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+ m->swap_watch.type = WATCH_SWAP;
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+ m->swap_watch.fd = fileno(m->proc_swaps);
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+
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+ if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, m->swap_watch.fd, &ev) < 0)
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+ return -errno;
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+ }
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+
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+ return 0;
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+}
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+
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int swap_dispatch_reload(Manager *m) {
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/* This function should go as soon as the kernel properly notifies us */
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+ int r;
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if (_likely_(!m->request_reload))
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return 0;
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m->request_reload = false;
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+ r = open_proc_swaps(m);
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+ if (r < 0)
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+ return r;
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+
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return swap_fd_event(m, EPOLLPRI);
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}
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@@ -1225,22 +1251,9 @@ static int swap_enumerate(Manager *m) {
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int r;
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assert(m);
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- if (!m->proc_swaps) {
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- struct epoll_event ev = {
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- .events = EPOLLPRI,
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- .data.ptr = &m->swap_watch,
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- };
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-
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- m->proc_swaps = fopen("/proc/swaps", "re");
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- if (!m->proc_swaps)
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- return (errno == ENOENT) ? 0 : -errno;
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-
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- m->swap_watch.type = WATCH_SWAP;
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- m->swap_watch.fd = fileno(m->proc_swaps);
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-
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- if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, m->swap_watch.fd, &ev) < 0)
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- return -errno;
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- }
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+ r = open_proc_swaps(m);
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+ if (r < 0)
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+ return r;
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r = swap_load_proc_swaps(m, false);
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if (r < 0)
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