There is no reason to take the tasklist lock here. The sighand structure is never referenced and and tsk->signal is guaranteed to stick around until tsk is freed. Further update_rlimit_cpu does not need the tasklist_lock. And the rlim_lock is used to guarantee mutual exclusion.
Signed-off-by: "Eric W. Biederman" <[email protected]> --- kernel/sys.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/kernel/sys.c b/kernel/sys.c index 8a94b4eabcaa..705f14b28134 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1380,13 +1380,6 @@ int do_prlimit(struct task_struct *tsk, unsigned int resource, return -EPERM; } - /* protect tsk->signal and tsk->sighand from disappearing */ - read_lock(&tasklist_lock); - if (!tsk->sighand) { - retval = -ESRCH; - goto out; - } - rlim = tsk->signal->rlim + resource; task_lock(tsk->group_leader); if (new_rlim) { @@ -1425,8 +1418,7 @@ int do_prlimit(struct task_struct *tsk, unsigned int resource, new_rlim->rlim_cur != RLIM_INFINITY && IS_ENABLED(CONFIG_POSIX_TIMERS)) update_rlimit_cpu(tsk, new_rlim->rlim_cur); -out: - read_unlock(&tasklist_lock); + return retval; } -- 2.10.1
