Re: [PATCH v7 0/3] io_uring: use release-acquire ordering for IORING_SETUP_R_DISABLED

[Gabriel Krisman Bertazi <krisman@suse.de>]

Caleb Sander Mateos <csander@purestorage.com> writes:

> io_uring_enter(), __io_msg_ring_data(), and io_msg_send_fd() read
> ctx->flags and ctx->submitter_task without holding the ctx's uring_lock.
> This means they may race with the assignment to ctx->submitter_task and
> the clearing of IORING_SETUP_R_DISABLED from ctx->flags in
> io_register_enable_rings(). Ensure the correct ordering of the
> ctx->flags and ctx->submitter_task memory accesses by storing to
> ctx->flags using release ordering and loading it using acquire ordering.
>
> Using release-acquire ordering for IORING_SETUP_R_DISABLED ensures the
> assignment to ctx->submitter_task in io_register_enable_rings() can't
> race with msg_ring's accesses, so drop the unneeded {READ,WRITE}_ONCE()
> and the NULL checks.

Hi Caleb,

This looks good, I don't have any comments.  Feel free to add:

Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>

Thanks,

-- 
Gabriel Krisman Bertazi