syscall_cp

syscall_cp

[Max Ruttenberg]

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What is syscall_cp and what is it supposed to do that syscall isn't?

-- 
Max Ruttenberg,
Member of the Technical Staff
Emu *Technology*
1400 E Angela Blvd, Unit 101
South Bend, IN 46617

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Re: syscall_cp

[Nathan McSween]

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cp is "cancellation point"

On Fri, Jan 29, 2016, 2:41 PM Max Ruttenberg <mruttenberg@emutechnology.com>
wrote:

> What is syscall_cp and what is it supposed to do that syscall isn't?
>
>
> --
> Max Ruttenberg,
> Member of the Technical Staff
> Emu *Technology*
> 1400 E Angela Blvd, Unit 101
> South Bend, IN 46617
>

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Re: syscall_cp

[Josiah Worcester]

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syscall_cp does largely the same thing as syscall. However, it also checks
for a current cancellation request, and exports some symbols (before and
after the syscall call) which are used in the thread cancellation
implementation. It makes it so the cancellation handler can know whether or
not the cancellation request happened during or after a syscall. (if
during, it needs to cancel the thread, if after, then it needs to continue
executing until the next cancellation point.)

On Fri, Jan 29, 2016 at 2:41 PM Max Ruttenberg <
mruttenberg@emutechnology.com> wrote:

> What is syscall_cp and what is it supposed to do that syscall isn't?
>
>
> --
> Max Ruttenberg,
> Member of the Technical Staff
> Emu *Technology*
> 1400 E Angela Blvd, Unit 101
> South Bend, IN 46617
>

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Re: syscall_cp

[Max Ruttenberg]

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and syscall_ret ??

On Fri, Jan 29, 2016 at 5:50 PM, Josiah Worcester <josiahw@gmail.com> wrote:

> syscall_cp does largely the same thing as syscall. However, it also checks
> for a current cancellation request, and exports some symbols (before and
> after the syscall call) which are used in the thread cancellation
> implementation. It makes it so the cancellation handler can know whether or
> not the cancellation request happened during or after a syscall. (if
> during, it needs to cancel the thread, if after, then it needs to continue
> executing until the next cancellation point.)
>
> On Fri, Jan 29, 2016 at 2:41 PM Max Ruttenberg <
> mruttenberg@emutechnology.com> wrote:
>
>> What is syscall_cp and what is it supposed to do that syscall isn't?
>>
>>
>> --
>> Max Ruttenberg,
>> Member of the Technical Staff
>> Emu *Technology*
>> 1400 E Angela Blvd, Unit 101
>> South Bend, IN 46617
>>
>


-- 
Max Ruttenberg,
Member of the Technical Staff
Emu *Technology*
1400 E Angela Blvd, Unit 101
South Bend, IN 46617

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Re: syscall_cp

[Rich Felker]

On Fri, Jan 29, 2016 at 06:03:54PM -0500, Max Ruttenberg wrote:
> and syscall_ret ??

It's a shortcut to avoid duplicating the errno update code in every
syscall wrapper. Instead they all just tail call to __syscall_ret
which returns -1 and sets errno if the return value was an error code,
and otherwise just passes through the return value.

BTW could you please reply inline-with/below quoted text on the list
rather than top-posting? Top-posting makes it hard to follow the flow
of conversation.

Rich


> On Fri, Jan 29, 2016 at 5:50 PM, Josiah Worcester <josiahw@gmail.com> wrote:
> 
> > syscall_cp does largely the same thing as syscall. However, it also checks
> > for a current cancellation request, and exports some symbols (before and
> > after the syscall call) which are used in the thread cancellation
> > implementation. It makes it so the cancellation handler can know whether or
> > not the cancellation request happened during or after a syscall. (if
> > during, it needs to cancel the thread, if after, then it needs to continue
> > executing until the next cancellation point.)
> >
> > On Fri, Jan 29, 2016 at 2:41 PM Max Ruttenberg <
> > mruttenberg@emutechnology.com> wrote:
> >
> >> What is syscall_cp and what is it supposed to do that syscall isn't?
> >>
> >>
> >> --
> >> Max Ruttenberg,
> >> Member of the Technical Staff
> >> Emu *Technology*
> >> 1400 E Angela Blvd, Unit 101
> >> South Bend, IN 46617
> >>
> >
> 
> 
> -- 
> Max Ruttenberg,
> Member of the Technical Staff
> Emu *Technology*
> 1400 E Angela Blvd, Unit 101
> South Bend, IN 46617