The patch titled
fork/exit: move tty_kref_put() outside of __cleanup_signal()
has been added to the -mm tree. Its filename is
fork-exit-move-tty_kref_put-outside-of-__cleanup_signal.patch
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------------------------------------------------------
Subject: fork/exit: move tty_kref_put() outside of __cleanup_signal()
From: Oleg Nesterov <oleg@xxxxxxxxxx>
tty_kref_put() has two callsites in copy_process() paths,
1. if copy_process() suceeds it is called before we copy
signal->tty from parent
2. otherwise it is called from __cleanup_signal() under
bad_fork_cleanup_signal: label
In both cases tty_kref_put() is not right and unneeded because we don't
have the balancing tty_kref_get(). Fortunately, this is harmless because
this can only happen without CLONE_THREAD, and in this case signal->tty
must be NULL.
Remove tty_kref_put() from copy_process() and __cleanup_signal(), and
change another caller of __cleanup_signal(), __exit_signal(), to call
tty_kref_put() by hand.
I hope this change makes sense by itself, but it is also needed to make
->signal refcountable.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/exit.c | 1 +
kernel/fork.c | 2 --
2 files changed, 1 insertion(+), 2 deletions(-)
diff -puN kernel/exit.c~fork-exit-move-tty_kref_put-outside-of-__cleanup_signal kernel/exit.c
--- a/kernel/exit.c~fork-exit-move-tty_kref_put-outside-of-__cleanup_signal
+++ a/kernel/exit.c
@@ -150,6 +150,7 @@ static void __exit_signal(struct task_st
* see account_group_exec_runtime().
*/
task_rq_unlock_wait(tsk);
+ tty_kref_put(sig->tty);
__cleanup_signal(sig);
}
}
diff -puN kernel/fork.c~fork-exit-move-tty_kref_put-outside-of-__cleanup_signal kernel/fork.c
--- a/kernel/fork.c~fork-exit-move-tty_kref_put-outside-of-__cleanup_signal
+++ a/kernel/fork.c
@@ -892,7 +892,6 @@ static int copy_signal(unsigned long clo
void __cleanup_signal(struct signal_struct *sig)
{
thread_group_cputime_free(sig);
- tty_kref_put(sig->tty);
kmem_cache_free(signal_cachep, sig);
}
@@ -1260,7 +1259,6 @@ static struct task_struct *copy_process(
p->nsproxy->pid_ns->child_reaper = p;
p->signal->leader_pid = pid;
- tty_kref_put(p->signal->tty);
p->signal->tty = tty_kref_get(current->signal->tty);
attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
attach_pid(p, PIDTYPE_SID, task_session(current));
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
linux-next.patch
posix-cpu-timers-reset-expire-cache-when-no-timer-is-running.patch
cpu-timers-simplify-rlimit_cpu-handling.patch
cpu-timers-cleanup-arm_timer.patch
cpu-timers-return-correct-previous-timer-reload-value.patch
cpu-timers-change-sigev_none-timer-implementation.patch
cpu-timers-assure-to-not-iterate-over-all-threads-in-fastpath_timer_check.patch
cpu-timers-optimize-run_posix_cpu_timers.patch
proc-cleanup-remove-unused-assignments.patch
kmod-add-init-function-to-usermodehelper.patch
exec-replace-call_usermodehelper_pipe-with-use-of-umh-init-function-and-resolve-limit.patch
umh-creds-convert-call_usermodehelper_keys-to-use-subprocess_info-init.patch
umh-creds-kill-subprocess_info-cred-logic.patch
call_usermodehelper-no-need-to-unblock-signals.patch
wait_for_helper-sigchld-from-user-space-can-lead-to-use-after-free.patch
call_usermodehelper-simplify-fix-umh_no_wait-case.patch
call_usermodehelper-umh_wait_exec-ignores-kernel_thread-failure.patch
coredump-factor-out-the-not-ispipe-file-checks.patch
coredump-cleanup-ispipe-code.patch
coredump-factor-out-put_cred-calls.patch
coredump-shift-down_writemmap_sem-into-coredump_wait.patch
exit-exit_notify-can-trust-signal-notify_count-0.patch
exit-change-zap_other_threads-to-count-sub-threads.patch
exit-avoid-sig-count-in-de_thread-__exit_signal-synchronization.patch
exit-avoid-sig-count-in-__exit_signal-to-detect-the-group-dead-case.patch
posix-cpu-timers-avoid-task-signal-=-null-checks.patch
ia64-ptrace_attach_sync_user_rbs-avoid-task-signal-=-null-checks.patch
fork-exit-move-tty_kref_put-outside-of-__cleanup_signal.patch
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