Re: [PATCH 3/9] port_fwd: Better parameterise procfs_scan_listen()

[Stefano Brivio <sbrivio@redhat.com>]

On Thu,  5 Oct 2023 14:44:39 +1100
David Gibson <david@gibson.dropbear.id.au> wrote:

> procfs_scan_listen() does some slightly clunky logic to deduce the fd it
> wants to use, the path it wants to open and the state it's looking for
> based on parameters for protocol, IP version and whether we're in the
> namespace.
> 
> However, the caller already has to make choices based on similar parameters
> so it can just pass in the things that procfs_scan_listen() needs directly.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  port_fwd.c | 53 +++++++++++++++++++++++------------------------------
>  1 file changed, 23 insertions(+), 30 deletions(-)
> 
> diff --git a/port_fwd.c b/port_fwd.c
> index 136a450..4b54877 100644
> --- a/port_fwd.c
> +++ b/port_fwd.c
> @@ -23,39 +23,27 @@
>  #include "passt.h"
>  #include "lineread.h"
>  
> +#define UDP_LISTEN	0x07
> +#define TCP_LISTEN	0x0a
> +
>  /**
>   * procfs_scan_listen() - Set bits for listening TCP or UDP sockets from procfs
> - * @proto:	IPPROTO_TCP or IPPROTO_UDP
> - * @ip_version:	IP version, V4 or V6
> - * @ns:		Use saved file descriptors for namespace if set
> + * @fd:		Pointer to fd for relevant /proc/net file
> + * @path:	Path to /proc/net file to open (if fd is -1)
> + * @lstate:	Code for listening state to scan for
>   * @map:	Bitmap where numbers of ports in listening state will be set
>   * @exclude:	Bitmap of ports to exclude from setting (and clear)
>   *
>   * #syscalls:pasta lseek
>   * #syscalls:pasta ppc64le:_llseek ppc64:_llseek armv6l:_llseek armv7l:_llseek
>   */
> -static void procfs_scan_listen(struct ctx *c, uint8_t proto, int ip_version,
> -			       int ns, uint8_t *map, const uint8_t *exclude)
> +static void procfs_scan_listen(int *fd, const char *path, unsigned int lstate,
> +			       uint8_t *map, const uint8_t *exclude)
>  {
> -	char *path, *line;
>  	struct lineread lr;
>  	unsigned long port;
>  	unsigned int state;
> -	int *fd;
> -
> -	if (proto == IPPROTO_TCP) {
> -		fd = &c->proc_net_tcp[ip_version][ns];
> -		if (ip_version == V4)
> -			path = "/proc/net/tcp";
> -		else
> -			path = "/proc/net/tcp6";
> -	} else {
> -		fd = &c->proc_net_udp[ip_version][ns];
> -		if (ip_version == V4)
> -			path = "/proc/net/udp";
> -		else
> -			path = "/proc/net/udp6";
> -	}
> +	char *line;
>  
>  	if (*fd != -1) {
>  		if (lseek(*fd, 0, SEEK_SET)) {
> @@ -74,8 +62,7 @@ static void procfs_scan_listen(struct ctx *c, uint8_t proto, int ip_version,
>  			continue;
>  
>  		/* See enum in kernel's include/net/tcp_states.h */

This comment should now be moved before #define UDP_LISTEN and
TCP_LISTEN, as it's not otherwise clear where they're coming from.

Given how late I'm reviewing all this, and that presumably you have a
bunch of series/patches based on it, I'm also fine to apply this and
patch it in a separate commit, or also fix this up on merge myself --
let me know.

Same for the comments to the next patches/series.

-- 
Stefano