"Shawn O. Pearce" <spearce@xxxxxxxxxxx> writes:
>> +static void try_to_free_from_threads(size_t size)
>> +{
>> + int self = pthread_equal(read_mutex_owner, pthread_self());
>> + if (!self)
>> + read_lock();
>> + release_pack_memory(size, -1);
>> + if (!self)
>> + read_unlock();
>> +}
>
> Is there any concern that a partially unset read_mutex_owner might
> look like the current thread's identity?
>
> That is, memset() can be setting the bytes one by one. If the lock
> is being released we might observe the current owner as ourselves
> if we see only part of that release, and our identity is the same
> as another thread, only with the lower-address bytes unset.
Yuck. I hope that it doesn't mean we need another mutex to protect the
owner data.
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