From: Christian Brauner <christian.brauner@ubuntu.com>
Date: Sat, 10 Feb 2018 22:25:18 +0000 (+0100)
Subject: lxclock: remove pthread_atfork_handlers
X-Git-Tag: lxc-2.0.10~334
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5cdc9b306b15f5986b4d71a36b03216f85b00d8f;p=thirdparty%2Flxc.git

lxclock: remove pthread_atfork_handlers

They shouldn't be needed anymore.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---

diff --git a/src/lxc/attach.c b/src/lxc/attach.c
index 502847533..cb1d7b977 100644
--- a/src/lxc/attach.c
+++ b/src/lxc/attach.c
@@ -1189,13 +1189,10 @@ int lxc_attach(const char *name, const char *lxcpath,
 		return -1;
 	}
 
-	/* Create intermediate subprocess, three reasons:
-	 *       1. Runs all pthread_atfork handlers and the child will no
-	 *          longer be threaded (we can't properly setns() in a threaded
-	 *          process).
-	 *       2. We can't setns() in the child itself, since we want to make
+	/* Create intermediate subprocess, two reasons:
+	 *       1. We can't setns() in the child itself, since we want to make
 	 *          sure we are properly attached to the pidns.
-	 *       3. Also, the initial thread has to put the attached process
+	 *       2. Also, the initial thread has to put the attached process
 	 *          into the cgroup, which we can only do if we didn't already
 	 *          setns() (otherwise, user namespaces will hate us).
 	 */
diff --git a/src/lxc/lxclock.c b/src/lxc/lxclock.c
index ccf9079da..600a7402d 100644
--- a/src/lxc/lxclock.c
+++ b/src/lxc/lxclock.c
@@ -317,23 +317,6 @@ void process_unlock(void)
 	unlock_mutex(&thread_mutex);
 }
 
-/* One thread can do fork() while another one is holding a mutex.
- * There is only one thread in child just after the fork(), so no one will ever release that mutex.
- * We setup a "child" fork handler to unlock the mutex just after the fork().
- * For several mutex types, unlocking an unlocked mutex can lead to undefined behavior.
- * One way to deal with it is to setup "prepare" fork handler
- * to lock the mutex before fork() and both "parent" and "child" fork handlers
- * to unlock the mutex.
- * This forbids doing fork() while explicitly holding the lock.
- */
-#ifdef HAVE_PTHREAD_ATFORK
-__attribute__((constructor))
-static void process_lock_setup_atfork(void)
-{
-	pthread_atfork(process_lock, process_unlock, process_unlock);
-}
-#endif
-
 int container_mem_lock(struct lxc_container *c)
 {
 	return lxclock(c->privlock, 0);