[RFC][PATCH 1/2] sighand: Count each thread group once in sighand_struct
From: Eric W. Biederman <hidden>
Date: 2017-04-01 05:19:38
Also in:
lkml
Subsystem:
exec & binfmt api, elf, memory management - core, scheduler, the rest · Maintainers:
Kees Cook, Andrew Morton, David Hildenbrand, Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
In practice either a thread group is either using a sighand_struct or it isn't. Therefore simplify things a bit and only increment the count in sighand_struct when a new thread group is created that uses the existing sighand_struct, and only decrement the count in sighand_struct when a thread group exits. As well as standing on it's own merits this has the potential to simply de_thread. Signed-off-by: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> --- kernel/exit.c | 2 +- kernel/fork.c | 6 ++++-- 2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/kernel/exit.c b/kernel/exit.c
index e126ebf2400c..8c5b3e106298 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c@@ -163,9 +163,9 @@ static void __exit_signal(struct task_struct *tsk) tsk->sighand = NULL; spin_unlock(&sighand->siglock); - __cleanup_sighand(sighand); clear_tsk_thread_flag(tsk, TIF_SIGPENDING); if (group_dead) { + __cleanup_sighand(sighand); flush_sigqueue(&sig->shared_pending); tty_kref_put(tty); }
diff --git a/kernel/fork.c b/kernel/fork.c
index 6c463c80e93d..fe6f1bf32bb9 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c@@ -1295,7 +1295,8 @@ static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) struct sighand_struct *sig; if (clone_flags & CLONE_SIGHAND) { - atomic_inc(¤t->sighand->count); + if (!(clone_flags & CLONE_THREAD)) + atomic_inc(¤t->sighand->count); return 0; } sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
@@ -1896,7 +1897,8 @@ static __latent_entropy struct task_struct *copy_process( if (!(clone_flags & CLONE_THREAD)) free_signal_struct(p->signal); bad_fork_cleanup_sighand: - __cleanup_sighand(p->sighand); + if (!(clone_flags & CLONE_THREAD)) + __cleanup_sighand(p->sighand); bad_fork_cleanup_fs: exit_fs(p); /* blocking */ bad_fork_cleanup_files:
--
2.10.1