Re: [RFC PATCH 3/3] futex: Use the task local hashmap.

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 2024-10-28 11:22:53 [+0100], Peter Zijlstra wrote:
> >  struct futex_hash_bucket *futex_hash(union futex_key *key)
> >  {
> > +	struct futex_hash_table *fht;
> >  	u32 hash = jhash2((u32 *)key, offsetof(typeof(*key), both.offset) / 4,
> >  			  key->both.offset);
> >  
> > +	fht = current->futex_hash_table;
> > +	if (fht && (key->both.offset & (FUT_OFF_INODE | FUT_OFF_MMSHARED)) == 0)
> > +		return &fht->queues[hash & (fht->slots - 1)];
> 
> Perhaps add a helper like:
> 
> static inline bool futex_key_is_private(struct futex_key *key)
> {
> 	/*
> 	 * Relies on get_futex_key() to set either bit for shared
> 	 * futexes -- see comment with union futex_key.
> 	 */
> 	return !(key->both.offset & (FUT_OFF_INODE | FUT_OFF_MMSHARED));
> }

Oki.

Sebastian