Re: [PATCH v5 7/7] passt: Move main event loop processing into passt_worker()

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Oct 21, 2025 at 11:01:16PM +0200, Laurent Vivier wrote:
> Extract the epoll event processing logic from main() into a separate
> passt_worker() function. This refactoring prepares the code for future
> threading support where passt_worker() will be called as a worker thread
> callback.
> 
> The new function handles:
> - Processing epoll events and dispatching to protocol handlers
> - Event statistics tracking and printing
> - Post-handler periodic tasks (timers, deferred work)
> - Migration handling
> 
> No functional changes, purely a code restructuring.
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  passt.c | 160 +++++++++++++++++++++++++++++++-------------------------
>  1 file changed, 88 insertions(+), 72 deletions(-)
> 
> diff --git a/passt.c b/passt.c
> index f1d78b79e2c3..5eabfa8f0c51 100644
> --- a/passt.c
> +++ b/passt.c
> @@ -229,6 +229,92 @@ static void print_stats(const struct ctx *c, const struct passt_stats *stats,
>  	lines_printed++;
>  }
>  
> +/**
> + * passt_worker() - Process epoll events and handle protocol operations
> + * @opaque:	Pointer to execution context (struct ctx)
> + * @nfds:	Number of file descriptors ready (epoll_wait return value)
> + * @events:	epoll_event array of ready file descriptors
> + */
> +static void passt_worker(void *opaque, int nfds, struct epoll_event *events)
> +{
> +	static struct passt_stats stats = { 0 };
> +	struct ctx *c = opaque;
> +	struct timespec now;
> +	int i;
> +
> +	if (clock_gettime(CLOCK_MONOTONIC, &now))
> +		err_perror("Failed to get CLOCK_MONOTONIC time");
> +
> +	for (i = 0; i < nfds; i++) {
> +		union epoll_ref ref = *((union epoll_ref *)&events[i].data.u64);
> +		uint32_t eventmask = events[i].events;
> +
> +		trace("%s: epoll event on %s %i (events: 0x%08x)",
> +		      c->mode == MODE_PASTA ? "pasta" : "passt",
> +		      EPOLL_TYPE_STR(ref.type), ref.fd, eventmask);
> +
> +		switch (ref.type) {
> +		case EPOLL_TYPE_TAP_PASTA:
> +			tap_handler_pasta(c, eventmask, &now);
> +			break;
> +		case EPOLL_TYPE_TAP_PASST:
> +			tap_handler_passt(c, eventmask, &now);
> +			break;
> +		case EPOLL_TYPE_TAP_LISTEN:
> +			tap_listen_handler(c, eventmask);
> +			break;
> +		case EPOLL_TYPE_NSQUIT_INOTIFY:
> +			pasta_netns_quit_inotify_handler(c, ref.fd);
> +			break;
> +		case EPOLL_TYPE_NSQUIT_TIMER:
> +			pasta_netns_quit_timer_handler(c, ref);
> +			break;
> +		case EPOLL_TYPE_TCP:
> +			tcp_sock_handler(c, ref, eventmask);
> +			break;
> +		case EPOLL_TYPE_TCP_SPLICE:
> +			tcp_splice_sock_handler(c, ref, eventmask);
> +			break;
> +		case EPOLL_TYPE_TCP_LISTEN:
> +			tcp_listen_handler(c, ref, &now);
> +			break;
> +		case EPOLL_TYPE_TCP_TIMER:
> +			tcp_timer_handler(c, ref);
> +			break;
> +		case EPOLL_TYPE_UDP_LISTEN:
> +			udp_listen_sock_handler(c, ref, eventmask, &now);
> +			break;
> +		case EPOLL_TYPE_UDP:
> +			udp_sock_handler(c, ref, eventmask, &now);
> +			break;
> +		case EPOLL_TYPE_PING:
> +			icmp_sock_handler(c, ref);
> +			break;
> +		case EPOLL_TYPE_VHOST_CMD:
> +			vu_control_handler(c->vdev, c->fd_tap, eventmask);
> +			break;
> +		case EPOLL_TYPE_VHOST_KICK:
> +			vu_kick_cb(c->vdev, ref, &now);
> +			break;
> +		case EPOLL_TYPE_REPAIR_LISTEN:
> +			repair_listen_handler(c, eventmask);
> +			break;
> +		case EPOLL_TYPE_REPAIR:
> +			repair_handler(c, eventmask);
> +			break;
> +		default:
> +			/* Can't happen */
> +			ASSERT(0);
> +		}
> +		stats.events[ref.type]++;
> +		print_stats(c, &stats, &now);
> +	}
> +
> +	post_handler(c, &now);
> +
> +	migrate_handler(c);
> +}
> +
>  /**
>   * main() - Entry point and main loop
>   * @argc:	Argument count
> @@ -246,8 +332,7 @@ static void print_stats(const struct ctx *c, const struct passt_stats *stats,
>  int main(int argc, char **argv)
>  {
>  	struct epoll_event events[NUM_EPOLL_EVENTS];
> -	struct passt_stats stats = { 0 };
> -	int nfds, i, devnull_fd = -1;
> +	int nfds, devnull_fd = -1;
>  	struct ctx c = { 0 };
>  	struct rlimit limit;
>  	struct timespec now;
> @@ -355,77 +440,8 @@ loop:
>  	if (nfds == -1 && errno != EINTR)
>  		die_perror("epoll_wait() failed in main loop");
>  
> -	if (clock_gettime(CLOCK_MONOTONIC, &now))
> -		err_perror("Failed to get CLOCK_MONOTONIC time");
> -
> -	for (i = 0; i < nfds; i++) {
> -		union epoll_ref ref = *((union epoll_ref *)&events[i].data.u64);
> -		uint32_t eventmask = events[i].events;
> -
> -		trace("%s: epoll event on %s %i (events: 0x%08x)",
> -		      c.mode == MODE_PASTA ? "pasta" : "passt",
> -		      EPOLL_TYPE_STR(ref.type), ref.fd, eventmask);
> -
> -		switch (ref.type) {
> -		case EPOLL_TYPE_TAP_PASTA:
> -			tap_handler_pasta(&c, eventmask, &now);
> -			break;
> -		case EPOLL_TYPE_TAP_PASST:
> -			tap_handler_passt(&c, eventmask, &now);
> -			break;
> -		case EPOLL_TYPE_TAP_LISTEN:
> -			tap_listen_handler(&c, eventmask);
> -			break;
> -		case EPOLL_TYPE_NSQUIT_INOTIFY:
> -			pasta_netns_quit_inotify_handler(&c, ref.fd);
> -			break;
> -		case EPOLL_TYPE_NSQUIT_TIMER:
> -			pasta_netns_quit_timer_handler(&c, ref);
> -			break;
> -		case EPOLL_TYPE_TCP:
> -			tcp_sock_handler(&c, ref, eventmask);
> -			break;
> -		case EPOLL_TYPE_TCP_SPLICE:
> -			tcp_splice_sock_handler(&c, ref, eventmask);
> -			break;
> -		case EPOLL_TYPE_TCP_LISTEN:
> -			tcp_listen_handler(&c, ref, &now);
> -			break;
> -		case EPOLL_TYPE_TCP_TIMER:
> -			tcp_timer_handler(&c, ref);
> -			break;
> -		case EPOLL_TYPE_UDP_LISTEN:
> -			udp_listen_sock_handler(&c, ref, eventmask, &now);
> -			break;
> -		case EPOLL_TYPE_UDP:
> -			udp_sock_handler(&c, ref, eventmask, &now);
> -			break;
> -		case EPOLL_TYPE_PING:
> -			icmp_sock_handler(&c, ref);
> -			break;
> -		case EPOLL_TYPE_VHOST_CMD:
> -			vu_control_handler(c.vdev, c.fd_tap, eventmask);
> -			break;
> -		case EPOLL_TYPE_VHOST_KICK:
> -			vu_kick_cb(c.vdev, ref, &now);
> -			break;
> -		case EPOLL_TYPE_REPAIR_LISTEN:
> -			repair_listen_handler(&c, eventmask);
> -			break;
> -		case EPOLL_TYPE_REPAIR:
> -			repair_handler(&c, eventmask);
> -			break;
> -		default:
> -			/* Can't happen */
> -			ASSERT(0);
> -		}
> -		stats.events[ref.type]++;
> -		print_stats(&c, &stats, &now);
> -	}
> -
> -	post_handler(&c, &now);
>  
> -	migrate_handler(&c);
> +	passt_worker(&c, nfds, events);
>  
>  	goto loop;
>  }
> -- 
> 2.51.0
> 

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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