On Sun, Mar 08, 2020 at 04:36:17PM -0500, Eric W. Biederman wrote:
This makes the code clearer and makes it easier to implement a mutex that is not taken over any locations that may block indefinitely waiting for userspace.
Signed-off-by: "Eric W. Biederman" ebiederm@xmission.com
fs/exec.c | 39 ++++++++++++++++++++++++++------------- 1 file changed, 26 insertions(+), 13 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c index c3f34791f2f0..ff74b9a74d34 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1194,6 +1194,23 @@ static int de_thread(struct task_struct *tsk) flush_itimer_signals(); #endif
- BUG_ON(!thread_group_leader(tsk));
- return 0;
+killed:
- /* protects against exit_notify() and __exit_signal() */
- read_lock(&tasklist_lock);
- sig->group_exit_task = NULL;
- sig->notify_count = 0;
- read_unlock(&tasklist_lock);
- return -EAGAIN;
+}
+static int unshare_sighand(struct task_struct *me) +{
- struct sighand_struct *oldsighand = me->sighand;
- if (refcount_read(&oldsighand->count) != 1) { struct sighand_struct *newsighand; /*
@@ -1210,23 +1227,13 @@ static int de_thread(struct task_struct *tsk) write_lock_irq(&tasklist_lock); spin_lock(&oldsighand->siglock);
rcu_assign_pointer(tsk->sighand, newsighand);
rcu_assign_pointer(me->sighand, newsighand);__cleanup_sighand(oldsighand); }
This is fine for now but we share an aweful lot of code with copy_sighand(). We should earmark this to look into consolidating the core operations into a common helper called from both copy_sighand() and unshare_sighand() maybe even dumbing it down to one helper. But not needed for now.
Otherwise: Acked-by: Christian Brauner christian.brauner@ubuntu.com