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Re: [PATCH] nptl: Add compiler barrier in nptl/tst-pthread-getattr
On Jul 30 2019, Florian Weimer <fweimer@redhat.com> wrote:
> * Andreas Schwab:
>
>> On Jul 29 2019, Florian Weimer <fweimer@redhat.com> wrote:
>>
>>> * Carlos O'Donell:
>>>
>>>>> tst-pthread-getattr.c: In function ‘allocate_and_test’:
>>>>> tst-pthread-getattr.c:54:10: error: function returns address of local variable [-Werror=return-local-addr]
>>>>> 54 | return mem;
>>>>> | ^~~
>>>>> In file included from ../include/alloca.h:3,
>>>>> from tst-pthread-getattr.c:26:
>>>>> ../stdlib/alloca.h:35:23: note: declared here
>>>>> 35 | # define alloca(size) __builtin_alloca (size)
>>>>> | ^~~~~~~~~~~~~~~~~~~~~~~
>>>>> tst-pthread-getattr.c:51:9: note: in expansion of macro ‘alloca’
>>>>> 51 | mem = alloca ((size_t) (mem - target));
>>>>> | ^~~~~~
>>>>>
>>>>> The address itself is used in a check in the caller, so using
>>>>> uintptr_t instead is reasonable.
>>>>
>>>> Any reason why we wouldn't move the test into the function?
>>>
>>> I think printf might fault because of its own stack usage (which can
>>> easily exceed half a page in some cases).
>>
>> Then return only the value of the same-page check and print it in the
>> parent.
>
> Sorry, what do you mean?
If you don't want to print it in allocate_and_test, print it in main.
Andreas.
--
Andreas Schwab, SUSE Labs, schwab@suse.de
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