Messages in this thread | | | From | Arnd Bergmann <> | Date | Tue, 1 Oct 2019 17:49:43 +0200 | Subject | Re: [PATCH] io_uring: use __kernel_timespec in timeout ABI |
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On Tue, Oct 1, 2019 at 5:38 PM Jens Axboe <axboe@kernel.dk> wrote: > > On 10/1/19 8:09 AM, Jens Axboe wrote: > > On 9/30/19 2:20 PM, Arnd Bergmann wrote: > >> All system calls use struct __kernel_timespec instead of the old struct > >> timespec, but this one was just added with the old-style ABI. Change it > >> now to enforce the use of __kernel_timespec, avoiding ABI confusion and > >> the need for compat handlers on 32-bit architectures. > >> > >> Any user space caller will have to use __kernel_timespec now, but this > >> is unambiguous and works for any C library regardless of the time_t > >> definition. A nicer way to specify the timeout would have been a less > >> ambiguous 64-bit nanosecond value, but I suppose it's too late now to > >> change that as this would impact both 32-bit and 64-bit users. > > > > Thanks for catching that, Arnd. Applied. > > On second thought - since there appears to be no good 64-bit timespec > available to userspace, the alternative here is including on in liburing.
What's wrong with using __kernel_timespec? Just the name? I suppose liburing could add a macro to give it a different name for its users.
> That seems kinda crappy in terms of API, so why not just use a 64-bit nsec > value as you suggest? There's on released kernel with this feature yet, so > there's nothing stopping us from just changing the API to be based on > a single 64-bit nanosecond timeout.
Certainly fine with me.
> + timeout = READ_ONCE(sqe->addr); > hrtimer_init(&req->timeout.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); > req->timeout.timer.function = io_timeout_fn; > - hrtimer_start(&req->timeout.timer, timespec_to_ktime(ts), > + hrtimer_start(&req->timeout.timer, ns_to_ktime(timeout),
It seems a little odd to use the 'addr' field as something that's not an address, and I'm not sure I understand the logic behind when you use a READ_ONCE() as opposed to simply accessing the sqe the way it is done a few lines earlier.
The time handling definitely looks good to me.
Arnd
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