Re: [PATCH 2/6] kernel: add task_sigpending() helper

Oleg Nesterov
2020-10-08T12:58:43Z

On 10/05, Jens Axboe wrote:
>
> static inline int signal_pending_state(long state, struct task_struct *p)
> {
> if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
> return 0;
> - if (!signal_pending(p))
> + if (!task_sigpending(p))
> return 0;

This looks obviously wrong. Say, schedule() in TASK_INTERRUPTIBLE should
not block if TIF_NOTIFY_SIGNAL is set.

With this change set_notify_signal() will not force the task to return
from wait_event_interruptible, mutex_lock_interruptible, etc.

> return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
> @@ -389,7 +394,7 @@ static inline bool fault_signal_pending(vm_fault_t fault_flags,
> {
> return unlikely((fault_flags & VM_FAULT_RETRY) &&
> (fatal_signal_pending(current) ||
> - (user_mode(regs) && signal_pending(current))));
> + (user_mode(regs) && task_sigpending(current))));

This looks unnecessary,

> @@ -773,7 +773,7 @@ static int ptrace_peek_siginfo(struct task_struct *child,
> data += sizeof(siginfo_t);
> i++;
>
> - if (signal_pending(current))
> + if (task_sigpending(current))

This too.

IMO, this patch should do s/signal_pending/task_sigpending/ only if it is
strictly needed for correctness.

Oleg.