diff options
author | Michal Sojka <sojkam1@fel.cvut.cz> | 2017-09-12 14:12:31 +0300 |
---|---|---|
committer | Yousong Zhou <yszhou4tech@gmail.com> | 2017-09-15 10:39:42 +0300 |
commit | 7a1057604ed2ad83434ed3be03728065b14a5e9c (patch) | |
tree | 24c780a18e7eb246adee4165731cd9f25c3b920c /uloop.c | |
parent | fd57eea9f37e447814afbf934db626288aac23c4 (diff) |
uloop: Fix race condition in SIGCHLD handling
When uloop_process_add() is called outside of uloop_run(), i.e. not
from a callback (which is the case of at least utrace and ujail),
child events can be missed. The reason is that when SIGCHILD handler
is installed in uloop_run(), after the uloop_process_add() is called,
then an initial signal could be missed.
Commit 4e3a47a ("uloop: use a waker for notifying sigchld and loop
cancel events", 2016-06-09) solved a similar problem and introduced
uloop_init() but forgot to move a call to uloop_setup_signals() there.
This is what this commit does.
Now, uloop_process_add() can be called any time after uloop_init()
without missing any event.
Signed-off-by: Michal Sojka <sojkam1@fel.cvut.cz>
Acked-by: Yousong Zhou <yszhou4tech@gmail.com>
Diffstat (limited to 'uloop.c')
-rw-r--r-- | uloop.c | 16 |
1 files changed, 8 insertions, 8 deletions
@@ -116,6 +116,8 @@ static int waker_init(void) return 0; } +static void uloop_setup_signals(bool add); + int uloop_init(void) { if (uloop_init_pollfd() < 0) @@ -126,6 +128,8 @@ int uloop_init(void) return -1; } + uloop_setup_signals(true); + return 0; } @@ -525,12 +529,7 @@ int uloop_run_timeout(int timeout) int next_time = 0; struct timeval tv; - /* - * Handlers are only updated for the first call to uloop_run() (and restored - * when this call is done). - */ - if (!uloop_run_depth++) - uloop_setup_signals(true); + uloop_run_depth++; uloop_status = 0; uloop_cancelled = false; @@ -553,14 +552,15 @@ int uloop_run_timeout(int timeout) uloop_run_events(next_time); } - if (!--uloop_run_depth) - uloop_setup_signals(false); + --uloop_run_depth; return uloop_status; } void uloop_done(void) { + uloop_setup_signals(false); + if (poll_fd >= 0) { close(poll_fd); poll_fd = -1; |