From: ebiederm@xmission.com (Eric W. Biederman)
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Aleksa Sarai <asarai@suse.com>,
Andy Lutomirski <luto@amacapital.net>,
Attila Fazekas <afazekas@redhat.com>, Jann Horn <jann@thejh.net>,
Kees Cook <keescook@chromium.org>,
Michal Hocko <mhocko@kernel.org>,
Ulrich Obergfell <uobergfe@redhat.com>,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org
Subject: [RFC][PATCH 1/2] sighand: Count each thread group once in sighand_struct
Date: Sat, 01 Apr 2017 00:14:17 -0500 [thread overview]
Message-ID: <8737dspv4m.fsf_-_@xmission.com> (raw)
In-Reply-To: <878tnkpv8h.fsf_-_@xmission.com> (Eric W. Biederman's message of "Sat, 01 Apr 2017 00:11:58 -0500")
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@xmission.com>
---
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
next prev parent reply other threads:[~2017-04-01 5:19 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-13 14:14 [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov
2017-02-13 14:15 ` [PATCH 1/2] exec: don't wait for zombie threads with cred_guard_mutex held Oleg Nesterov
2017-02-13 16:12 ` kbuild test robot
2017-02-13 16:47 ` Oleg Nesterov
2017-02-13 16:39 ` kbuild test robot
2017-02-13 17:27 ` Mika Penttilä
2017-02-13 18:01 ` Oleg Nesterov
2017-02-13 18:04 ` [PATCH V2 " Oleg Nesterov
2017-02-16 11:42 ` Eric W. Biederman
2017-02-20 15:22 ` Oleg Nesterov
2017-02-20 15:36 ` Oleg Nesterov
2017-02-20 22:30 ` Eric W. Biederman
2017-02-21 17:53 ` Oleg Nesterov
2017-02-21 20:20 ` Eric W. Biederman
2017-02-22 17:41 ` Oleg Nesterov
2017-02-17 4:42 ` Eric W. Biederman
2017-02-20 15:50 ` Oleg Nesterov
2017-02-13 14:15 ` [PATCH 2/2] ptrace: ensure PTRACE_EVENT_EXIT won't stop if the tracee is killed by exec Oleg Nesterov
2017-02-24 16:03 ` [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov
2017-03-03 1:05 ` Eric W. Biederman
2017-03-03 17:33 ` Oleg Nesterov
2017-03-03 18:23 ` Eric W. Biederman
2017-03-03 18:59 ` Eric W. Biederman
2017-03-03 20:06 ` Eric W. Biederman
2017-03-03 20:11 ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Eric W. Biederman
2017-03-04 17:03 ` Oleg Nesterov
2017-03-30 8:07 ` Eric W. Biederman
2017-04-01 5:11 ` [RFC][PATCH 0/2] exec: Fixing ptrace'd mulit-threaded hang Eric W. Biederman
2017-04-01 5:14 ` Eric W. Biederman [this message]
2017-04-01 5:16 ` [RFC][PATCH 2/2] exec: If possible don't wait for ptraced threads to be reaped Eric W. Biederman
2017-04-02 15:35 ` Oleg Nesterov
2017-04-02 18:53 ` Eric W. Biederman
2017-04-03 18:12 ` Oleg Nesterov
2017-04-03 21:04 ` Eric W. Biederman
2017-04-05 16:44 ` Oleg Nesterov
2017-04-02 15:38 ` [RFC][PATCH 0/2] exec: Fixing ptrace'd mulit-threaded hang Oleg Nesterov
2017-04-02 22:50 ` [RFC][PATCH v2 0/5] " Eric W. Biederman
2017-04-02 22:51 ` [RFC][PATCH v2 1/5] ptrace: Don't wait in PTRACE_O_TRACEEXIT for exec or coredump Eric W. Biederman
2017-04-05 16:19 ` Oleg Nesterov
2017-04-02 22:51 ` [RFC][PATCH v2 2/5] sighand: Count each thread group once in sighand_struct Eric W. Biederman
2017-04-02 22:52 ` [RFC][PATCH v2 3/5] clone: Disallown CLONE_THREAD with a shared sighand_struct Eric W. Biederman
2017-04-05 16:24 ` Oleg Nesterov
2017-04-05 17:34 ` Eric W. Biederman
2017-04-05 18:11 ` Oleg Nesterov
2017-04-02 22:53 ` [RFC][PATCH v2 4/5] exec: If possible don't wait for ptraced threads to be reaped Eric W. Biederman
2017-04-05 16:15 ` Oleg Nesterov
2017-04-02 22:57 ` [RFC][PATCH v2 5/5] signal: Don't allow accessing signal_struct by old threads after exec Eric W. Biederman
2017-04-05 16:18 ` Oleg Nesterov
2017-04-05 18:16 ` Eric W. Biederman
2017-04-06 15:48 ` Oleg Nesterov
2017-04-02 16:15 ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Oleg Nesterov
2017-04-02 21:07 ` Eric W. Biederman
2017-04-03 18:37 ` Oleg Nesterov
2017-04-03 22:49 ` Eric W. Biederman
2017-04-03 22:49 ` scope of cred_guard_mutex Eric W. Biederman
2017-04-05 16:08 ` Oleg Nesterov
2017-04-05 16:11 ` Kees Cook
2017-04-05 17:53 ` Eric W. Biederman
2017-04-05 18:15 ` Oleg Nesterov
2017-04-06 15:55 ` Oleg Nesterov
2017-04-07 22:07 ` Kees Cook
2017-09-04 3:19 ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Robert O'Callahan
2017-03-04 16:54 ` [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov
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