Re: [PATCH] ipc: optimize semget/shmget/msgget for lots of keys

[Davidlohr Bueso]

On Mon, 31 Jul 2017, Guillaume Knispel wrote:
> static int __init ipc_init(void)
> {
> -	sem_init();
> -	msg_init();
> +	int err_sem, err_msg;
> +
> +	err_sem = sem_init();
> +	WARN(err_sem, "ipc: sysV sem_init failed: %d\n", err_sem);
> +	err_msg = msg_init();
> +	WARN(err_msg, "ipc: sysV msg_init failed: %d\n", err_msg);
> 	shm_init();

This shows the ugliness of the underlying ipc init asymmetry. Specifically,
140d0b2108f (Do 'shm_init_ns()' in an early pure_initcall) was the final
nail in the coffin to fix an exit_shm() race.

While normally we could just initialize the ipc_ids fields statically and
be over with initcall dependencies, your patch will require inits be done
dynamically for the rhashtable_init(). Oh well.

Also, why do you do this?

> -pure_initcall(ipc_ns_init);
> +core_initcall(ipc_ns_init);

Thanks,
Davidlohr