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| author | Oleg Nesterov <oleg@redhat.com> | 2010-05-26 23:43:15 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-27 18:12:46 +0200 |
| commit | 4dec2a91fd7e8815d730afbfdcf085cbf53433ac (patch) | |
| tree | cd33cc793abf532d4ca212d09c1e8d3154a8b530 | |
| parent | ia64: ptrace_attach_sync_user_rbs: avoid "task->signal != NULL" checks (diff) | |
| download | linux-4dec2a91fd7e8815d730afbfdcf085cbf53433ac.tar.xz linux-4dec2a91fd7e8815d730afbfdcf085cbf53433ac.zip | |
fork/exit: move tty_kref_put() outside of __cleanup_signal()
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@redhat.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | kernel/exit.c | 1 | ||||
| -rw-r--r-- | kernel/fork.c | 2 |
2 files changed, 1 insertions, 2 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 4c70c377d21f..4a72f1753edb 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -149,6 +149,7 @@ static void __exit_signal(struct task_struct *tsk) * see account_group_exec_runtime(). */ task_rq_unlock_wait(tsk); + tty_kref_put(sig->tty); __cleanup_signal(sig); } } diff --git a/kernel/fork.c b/kernel/fork.c index 2e9cc3139ec6..b7879ef6e7cd 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -892,7 +892,6 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) void __cleanup_signal(struct signal_struct *sig) { thread_group_cputime_free(sig); - tty_kref_put(sig->tty); kmem_cache_free(signal_cachep, sig); } @@ -1263,7 +1262,6 @@ static struct task_struct *copy_process(unsigned long clone_flags, 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)); |