[lttng-dev] [PATCH 6/7] Fix: uatomic_or() need retyping to uintptr_t in rculfhash.c

[Ondřej Surý]

> On 20. 3. 2023, at 19:31, Mathieu Desnoyers <mathieu.desnoyers at efficios.com> wrote:
> 
> On 2023-03-17 17:37, Ondřej Surý via lttng-dev wrote:
>> When adding REMOVED_FLAG to the pointers in the rculfhash
>> implementation, retype the generic pointer to uintptr_t to fix the
>> compiler error.
> 
> What is the compiler error ? I'm wondering whether the expected choice
> to match the rest of this file's content would be to use "uintptr_t *" or "unsigned long *" ?

This is the error:

rculfhash.c:1201:2: error: address argument to atomic operation must be a pointer to integer ('struct cds_lfht_node **' invalid)
        uatomic_or(&node->next, REMOVED_FLAG);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../include/urcu/uatomic.h:60:8: note: expanded from macro 'uatomic_or'
        (void)__atomic_or_fetch((addr), (mask), __ATOMIC_RELAXED)
              ^                 ~~~~~~
rculfhash.c:1444:3: error: address argument to atomic operation must be a pointer to integer ('struct cds_lfht_node **' invalid)
                uatomic_or(&fini_bucket->next, REMOVED_FLAG);
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../include/urcu/uatomic.h:60:8: note: expanded from macro 'uatomic_or'
        (void)__atomic_or_fetch((addr), (mask), __ATOMIC_RELAXED)
              ^                 ~~~~~~

uintptr_t is defined as "unsigned integer type capable of holding a pointer to void" while unsigned long is at least 32-bit;

I guess that works in a practise, but using unsigned long to retype the pointers might blow up (thinking of x32 which I know
little about, but it's kind of hybrid architecture, isn't it?)

Ondrej
--
Ondřej Surý (He/Him)
ondrej at sury.org