Use valid address in pthread_setspecific to silence warnings #162
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karianna
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Sep 4, 2024
dagood
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Sep 4, 2024
thread_setup_unix.c
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| @@ -9,6 +9,9 @@ static pthread_mutex_t *mutex_buf = NULL; | |||
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| static pthread_key_t destructor_key; | |||
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| /* Used in pthread_setspecific. See https://github.com/microsoft/go/issues/1305. */ | |||
| static char stub; | |||
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Does this need to exist at the global scope, or could static char stub; or char stub; be declared just before the call?
If there's no difference, I think putting the declaration inside thread_id would be a bit clearer. And IMO putting it on the stack (if possible) raises the fewest questions from a reader's perspective. 😄
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Looks putting the variable in the function scope also works, and it does look clearer. I'll keep the static keyword, though, I would rather not pass a pointer to a stack-allocated variable that can be used outside the function frame, just in case it is used somewhere 😅.
Co-authored-by: Davis Goodin <[email protected]>
qmuntal
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* use valid address in pthread_setspecific to silence warnings * Update thread_setup_unix.c Co-authored-by: Davis Goodin <[email protected]> * use local variable instead of global --------- Co-authored-by: Davis Goodin <[email protected]> (cherry picked from commit 6f4d87d)
dagood
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…168) * use valid address in pthread_setspecific to silence warnings * Update thread_setup_unix.c Co-authored-by: Davis Goodin <[email protected]> * use local variable instead of global --------- Co-authored-by: Davis Goodin <[email protected]> (cherry picked from commit 6f4d87d)
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Building with a newer glibc (probably since 2.34) causes the following warning:
The is caused by the
accessattribute annotation ofpthread_setspecific, which was recently added.GCC defines the none mode of access as:
The access mode none specifies that the pointer to which it applies is not used to access the referenced object at all. Unless the pointer is null the pointed-to object must exist and have at least the size as denoted by the size-index argument. The object need not be initialized. The mode is intended to be used as a means to help validate the expected object size, for example in functions that call __builtin_object_size. See Object Size Checking.
We are passing
(void*)1as a NULL pointer, which doesn't meet thenoneaccess requirements. This PR fixes that by using a static stub char pointer.Fixes microsoft/go#1305.