Re: [RESEND PATCH] ptrace: take into account saved_sigmask in PTRACE_{GET,SET}SIGMASK

[Oleg Nesterov]

On 03/19, Andrei Vagin wrote:
>
> There are a few system calls (pselect, ppoll, etc) which replace a task
> sigmask while they are running in a kernel-space
>
> When a task calls one of these syscalls, the kernel saves a current
> sigmask in task->saved_sigmask and sets a syscall sigmask.
>
> On syscall-exit-stop, ptrace traps a task before restoring the
> saved_sigmask, so PTRACE_GETSIGMASK returns the syscall sigmask and
> PTRACE_SETSIGMASK does nothing, because its sigmask is replaced by
> saved_sigmask, when the task returns to user-space.
>
> This patch fixes this problem.  PTRACE_GET_SIGMASK returns saved_sigmask
> is it's set.  PTRACE_SETSIGMASK drops the TIF_RESTORE_SIGMASK flag.

Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>