Re: [RFC PATCH v7 7/7] Restartable sequences: self-tests

[Dave Watson]

>> +static inline __attribute__((always_inline))
>> +bool rseq_finish(struct rseq_lock *rlock,
>> + intptr_t *p, intptr_t to_write,
>> + struct rseq_state start_value)

>> This ABI looks like it will work fine for our use case. I don't think it
>> has been mentioned yet, but we may still need multiple asm blocks
>> for differing numbers of writes. For example, an array-based freelist push:

>> void push(void *obj) {
>> if (index < maxlen) {
>> freelist[index++] = obj;
>> }
>> }

>> would be more efficiently implemented with a two-write rseq_finish:

>> rseq_finish2(&freelist[index], obj, // first write
>> &index, index + 1, // second write
>> ...);

> Would pairing one rseq_start with two rseq_finish do the trick
> there ?

Yes, two rseq_finish works, as long as the extra rseq management overhead
is not substantial.