Subject: Re: [PATCH 1/3] net: socket: enable async read and write

From: Tadeusz Struk <[email-masked]>
Date: Fri, 30 Jan 2015 10:30:46 -0800

On 01/29/2015 03:13 PM, Tadeusz Struk wrote:
> AIO read or write are not currently supported on sockets.
> This patch enables real socket async read/write.
> 
> Please note - this patch is generated against cryptodev.
> 
> Signed-off-by: Tadeusz Struk <[email-masked]>
> ---
>  include/net/sock.h |    2 ++
>  net/socket.c       |   48 ++++++++++++++++++++++++++++++++++++++----------
>  2 files changed, 40 insertions(+), 10 deletions(-)
> 
> diff --git a/include/net/sock.h b/include/net/sock.h
> index 2210fec..2c7d160 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -1397,6 +1397,8 @@ static inline struct kiocb *siocb_to_kiocb(struct sock_iocb *si)
>  	return si->kiocb;
>  }
>  
> +void sock_aio_complete(struct kiocb *iocb, long res, long res2);
> +
>  struct socket_alloc {
>  	struct socket socket;
>  	struct inode vfs_inode;
> diff --git a/net/socket.c b/net/socket.c
> index a2c33a4..368fa9f 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -866,14 +866,25 @@ static ssize_t sock_splice_read(struct file *file, loff_t *ppos,
>  	return sock->ops->splice_read(sock, ppos, pipe, len, flags);
>  }
>  
> +void sock_aio_complete(struct kiocb *iocb, long res, long res2)
> +{
> +	struct sock_iocb *siocb = kiocb_to_siocb(iocb);
> +
> +	kfree(siocb);
> +	aio_complete(iocb, res, res2);
> +}
> +EXPORT_SYMBOL(sock_aio_complete);
> +
>  static struct sock_iocb *alloc_sock_iocb(struct kiocb *iocb,
>  					 struct sock_iocb *siocb)
>  {
> -	if (!is_sync_kiocb(iocb))
> -		BUG();
> +	if (!siocb)
> +		siocb = kmalloc(sizeof(*siocb), GFP_KERNEL);
>  
> -	siocb->kiocb = iocb;
> -	iocb->private = siocb;
> +	if (siocb) {
> +		siocb->kiocb = iocb;
> +		iocb->private = siocb;
> +	}
>  	return siocb;
>  }
>  
> @@ -901,7 +912,8 @@ static ssize_t do_sock_read(struct msghdr *msg, struct kiocb *iocb,
>  static ssize_t sock_aio_read(struct kiocb *iocb, const struct iovec *iov,
>  				unsigned long nr_segs, loff_t pos)
>  {
> -	struct sock_iocb siocb, *x;
> +	struct sock_iocb siocb, *x = NULL;
> +	int ret;
>  
>  	if (pos != 0)
>  		return -ESPIPE;
> @@ -909,11 +921,18 @@ static ssize_t sock_aio_read(struct kiocb *iocb, const struct iovec *iov,
>  	if (iocb->ki_nbytes == 0)	/* Match SYS5 behaviour */
>  		return 0;
>  
> +	if (is_sync_kiocb(iocb))
> +		x = &siocb;
>  
> -	x = alloc_sock_iocb(iocb, &siocb);
> +	x = alloc_sock_iocb(iocb, x);
>  	if (!x)
>  		return -ENOMEM;
> -	return do_sock_read(&x->async_msg, iocb, iocb->ki_filp, iov, nr_segs);
> +	ret = do_sock_read(&x->async_msg, iocb, iocb->ki_filp, iov, nr_segs);
> +
> +	if (!is_sync_kiocb(iocb) && ret != -EIOCBQUEUED)
> +		kfree(x);
> +
> +	return ret;
>  }
>  
>  static ssize_t do_sock_write(struct msghdr *msg, struct kiocb *iocb,
> @@ -942,16 +961,25 @@ static ssize_t do_sock_write(struct msghdr *msg, struct kiocb *iocb,
>  static ssize_t sock_aio_write(struct kiocb *iocb, const struct iovec *iov,
>  			  unsigned long nr_segs, loff_t pos)
>  {
> -	struct sock_iocb siocb, *x;
> +	struct sock_iocb siocb, *x = NULL;
> +	int ret;
>  
>  	if (pos != 0)
>  		return -ESPIPE;
>  
> -	x = alloc_sock_iocb(iocb, &siocb);
> +	if (is_sync_kiocb(iocb))
> +		x = &siocb;
> +
> +	x = alloc_sock_iocb(iocb, x);
>  	if (!x)
>  		return -ENOMEM;
>  
> -	return do_sock_write(&x->async_msg, iocb, iocb->ki_filp, iov, nr_segs);
> +	ret = do_sock_write(&x->async_msg, iocb, iocb->ki_filp, iov, nr_segs);
> +
> +	if (!is_sync_kiocb(iocb) && ret != -EIOCBQUEUED)
> +		kfree(x);
> +
> +	return ret;
>  }
>  
>  /*

Hi Herbert,
Just noticed that the struct sock_iocb has just been removed on net-next
(see [1]). What we can do is to call aio_complete() directly from
algif_skcipher, assuming that it is ok to call asynchronous read or
write with the struct msghdr allocated on the stack.
Please let me know what you think.
Thanks,
Tadeusz

[1]
https://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=7cc05662682da4b0e0a4fdf3c3f190577803ae81