Re: [PATCH 05/18] Add io_uring IO interface

On Tue, Jan 29, 2019 at 4:20 PM Jens Axboe [off-list ref] wrote:

On 1/29/19 4:58 AM, Arnd Bergmann wrote:

quoted

On Tue, Jan 29, 2019 at 7:30 AM Christoph Hellwig [off-list ref] wrote:

quoted

quoted

On Mon, Jan 28, 2019 at 11:25:12AM -0700, Jens Axboe wrote:

quoted

Especially with poll support now in the series, don't we need a ѕigmask
argument similar to pselect/ppoll/io_pgetevents now to deal with signal
blocking during waiting for events?

Is there any way to avoid passing in the sigset_t size? If it's just a
32-bit/64-bit thing, surely the in_compat_syscall() could cover it? Or
are there other cases that need to be catered to?

As far as I can tell we never look at it, never looked at it and don't
have any plans to look at it anytime soon.  But when I tried to omit
it for io_pgetevents I got stong pushback and thus had to add the
crazy double indirection calling convention.

That's good info. I am currently using set_user_sigmask() for it.
I'd really like to avoid having to pass in a sigset_t size for the
system call, however.

I really wouldn't do it, given that all other signal handling interfaces
are prepared for longer signal masks. You /could/ probably extend
it later with a flags bit to signify a longer mask instead of using
the entire register to hold the bit length, it just seems really
inconsistent with all other system calls.

      Arnd

What's the best way of achieving that? Can I get
away with doing something like this:

        if (in_compat_syscall()) {
                const compat_sigset_t __user *compat_sig;

                compat_sig = (const compat_sigset_t __user *) sig;
                ret = set_compat_user_sigmask(compat_sig, &ksigmask,
                                                &sigsaved, _NSIG_WORDS);
        } else {
                ret = set_user_sigmask(sig, &ksigmask, &sigsaved,
                                                _NSIG_WORDS);
        }

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