Re: kern_sig.c

[Masao Uebayashi <uebayasi%gmail.com@localhost>]

On Sat, Nov 21, 2015 at 8:13 PM, Masao Uebayashi <uebayasi%gmail.com@localhost> wrote:
> I'm too young to understand how signal works in kernel.  But I guess
> I'm not alone.
>
> I think that renaming things a bit would help people to understand the code.
>
> *
> - sendsig() -> netbsd_sendsig()
> - trapsignal() -> netbsd_trapsignal()
>
> These are native emul functions of e_sendsig and e_trapsignal respectively.
>
> *
>
> - postsig() -> sendsig()
>
> This is so badly named and incredibly confusing, as these is a
> function called sigpost() which is completely different.
>
> sigpost() posts a signal to a signal queue.  sigpost() can be called
> from anywhere including interrupt context, because all it does is to
>
> sendsig(), the function which is called as postsig() now, and referred
> to by the signal(9) manual page and comments all over the tree, is the
> sequence of code that is called when a signal is delivered (some
> actual action is taking place).
>
> sendsig() ("postsig()") is only called from userret() -> mi_userret()
> -> lwp_userret().  If a pending signal is found and it is decided to
> be delivered, trap frame is overwritten by signal handler trampoline.

This should have been read as: trap frame is replaced with signal
handler trampoline by sendsig_siginfo().