* Re: [PATCH liburing] examples/ucontext-cp.c: cope with variable SIGSTKSZ
[not found] ` <[email protected]>
@ 2021-04-22 14:22 ` Stefano Garzarella
2021-04-23 14:13 ` Pavel Begunkov
0 siblings, 1 reply; 2+ messages in thread
From: Stefano Garzarella @ 2021-04-22 14:22 UTC (permalink / raw)
To: Stefan Hajnoczi
Cc: io-uring, Pavel Begunkov, H.J. Lu, libc-alpha, Jens Axboe,
linux-block
+Cc: [email protected]
+Cc: Pavel Begunkov <[email protected]>
Original message:
https://www.spinics.net/lists/linux-block/msg67077.html
On Thu, Apr 22, 2021 at 10:59:42AM +0100, Stefan Hajnoczi wrote:
>On Mon, Apr 19, 2021 at 11:38:07AM -0700, H.J. Lu wrote:
>> On Mon, Apr 19, 2021 at 7:35 AM Stefan Hajnoczi <[email protected]> wrote:
>> >
>> > On Tue, Apr 13, 2021 at 04:03:19PM +0100, Stefan Hajnoczi wrote:
>> > > The size of C arrays at file scope must be constant. The following
>> > > compiler error occurs with recent upstream glibc (2.33.9000):
>> > >
>> > > CC ucontext-cp
>> > > ucontext-cp.c:31:23: error: variably modified ‘stack_buf’ at file scope
>> > > 31 | unsigned char stack_buf[SIGSTKSZ];
>> > > | ^~~~~~~~~
>> > > make[1]: *** [Makefile:26: ucontext-cp] Error 1
>> > >
>> > > The following glibc commit changed SIGSTKSZ from a constant value to a
>> > > variable:
>> > >
>> > > commit 6c57d320484988e87e446e2e60ce42816bf51d53
>> > > Author: H.J. Lu <[email protected]>
>> > > Date: Mon Feb 1 11:00:38 2021 -0800
>> > >
>> > > sysconf: Add _SC_MINSIGSTKSZ/_SC_SIGSTKSZ [BZ #20305]
>> > > ...
>> > > +# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
>> > >
>> > > Allocate the stack buffer explicitly to avoid declaring an array at file
>> > > scope.
>> > >
>> > > Cc: H.J. Lu <[email protected]>
>> > > Signed-off-by: Stefan Hajnoczi <[email protected]>
>> > > ---
>> > > Perhaps the glibc change needs to be revised before releasing glibc 2.34
>> > > since it might break applications. That's up to the glibc folks. It
>> > > doesn't hurt for liburing to take a safer approach that copes with the
>> > > SIGSTKSZ change in any case.
>> >
>> > glibc folks, please take a look. The commit referenced above broke
>> > compilation of liburing's tests. It's possible that applications will
>> > hit similar issues. Can you check whether the SIGSTKSZ change needs to
>> > be reverted/fixed before releasing glibc 2.34?
>> >
>>
>> It won't be changed for glibc 2.34.
>
>Thanks for the response, H.J. and Paul.
>
>In that case liburing needs this patch.
>
I think so:
Reviewed-by: Stefano Garzarella <[email protected]>
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH liburing] examples/ucontext-cp.c: cope with variable SIGSTKSZ
2021-04-22 14:22 ` [PATCH liburing] examples/ucontext-cp.c: cope with variable SIGSTKSZ Stefano Garzarella
@ 2021-04-23 14:13 ` Pavel Begunkov
0 siblings, 0 replies; 2+ messages in thread
From: Pavel Begunkov @ 2021-04-23 14:13 UTC (permalink / raw)
To: Stefano Garzarella, Stefan Hajnoczi
Cc: io-uring, H.J. Lu, libc-alpha, Jens Axboe, linux-block
On 4/22/21 3:22 PM, Stefano Garzarella wrote:
> +Cc: [email protected]
> +Cc: Pavel Begunkov <[email protected]>
>
> Original message: https://www.spinics.net/lists/linux-block/msg67077.html
>
> On Thu, Apr 22, 2021 at 10:59:42AM +0100, Stefan Hajnoczi wrote:
>> On Mon, Apr 19, 2021 at 11:38:07AM -0700, H.J. Lu wrote:
>>> On Mon, Apr 19, 2021 at 7:35 AM Stefan Hajnoczi <[email protected]> wrote:
>>> >
>>> > On Tue, Apr 13, 2021 at 04:03:19PM +0100, Stefan Hajnoczi wrote:
>>> > > The size of C arrays at file scope must be constant. The following
>>> > > compiler error occurs with recent upstream glibc (2.33.9000):
>>> > >
>>> > > CC ucontext-cp
>>> > > ucontext-cp.c:31:23: error: variably modified ‘stack_buf’ at file scope
>>> > > 31 | unsigned char stack_buf[SIGSTKSZ];
>>> > > | ^~~~~~~~~
>>> > > make[1]: *** [Makefile:26: ucontext-cp] Error 1
>>> > >
>>> > > The following glibc commit changed SIGSTKSZ from a constant value to a
>>> > > variable:
>>> > >
>>> > > commit 6c57d320484988e87e446e2e60ce42816bf51d53
>>> > > Author: H.J. Lu <[email protected]>
>>> > > Date: Mon Feb 1 11:00:38 2021 -0800
>>> > >
>>> > > sysconf: Add _SC_MINSIGSTKSZ/_SC_SIGSTKSZ [BZ #20305]
>>> > > ...
>>> > > +# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
>>> > >
>>> > > Allocate the stack buffer explicitly to avoid declaring an array at file
>>> > > scope.
>>> > >
>>> > > Cc: H.J. Lu <[email protected]>
>>> > > Signed-off-by: Stefan Hajnoczi <[email protected]>
>>> > > ---
>>> > > Perhaps the glibc change needs to be revised before releasing glibc 2.34
>>> > > since it might break applications. That's up to the glibc folks. It
>>> > > doesn't hurt for liburing to take a safer approach that copes with the
>>> > > SIGSTKSZ change in any case.
>>> >
>>> > glibc folks, please take a look. The commit referenced above broke
>>> > compilation of liburing's tests. It's possible that applications will
>>> > hit similar issues. Can you check whether the SIGSTKSZ change needs to
>>> > be reverted/fixed before releasing glibc 2.34?
>>> >
>>>
>>> It won't be changed for glibc 2.34.
>>
>> Thanks for the response, H.J. and Paul.
>>
>> In that case liburing needs this patch.
>>
>
> I think so:
>
> Reviewed-by: Stefano Garzarella <[email protected]>
Right, and there are already people complaining
https://github.com/axboe/liburing/issues/320
--
Pavel Begunkov
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2021-04-22 14:22 ` [PATCH liburing] examples/ucontext-cp.c: cope with variable SIGSTKSZ Stefano Garzarella
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