Re: [PATCH v2 1/8] icmp, udp: Pad time_t timestamp to 64-bit to ease state migration

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

[-- Attachment #1: Type: text/plain, Size: 2160 bytes --]

On Wed, Jan 29, 2025 at 12:39:33AM +0100, Stefano Brivio wrote:
> That's the only field in flows with different storage sizes depending
> on the architecture: it's usually 4-byte wide on 32-bit architectures,
> except for arc and x32 where it's 8 bytes, and 8-byte wide on 64-bit
> machines.
> 
> By keeping flow entries the same size across architectures, we avoid
> having to expand or shrink table entries upon migration.
> 
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Ugly, but necessary for this v1 approach.

> ---
>  icmp_flow.h | 6 +++++-
>  udp_flow.h  | 6 +++++-
>  2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/icmp_flow.h b/icmp_flow.h
> index fb93801..da7e255 100644
> --- a/icmp_flow.h
> +++ b/icmp_flow.h
> @@ -13,6 +13,7 @@
>   * @seq:	Last sequence number sent to tap, host order, -1: not sent yet
>   * @sock:	"ping" socket
>   * @ts:		Last associated activity from tap, seconds
> + * @ts_storage:	Pad @ts to 64-bit storage to keep state migration sane
>   */
>  struct icmp_ping_flow {
>  	/* Must be first element */
> @@ -20,7 +21,10 @@ struct icmp_ping_flow {
>  
>  	int seq;
>  	int sock;
> -	time_t ts;
> +	union {
> +		time_t ts;
> +		uint64_t ts_storage;
> +	};
>  };
>  
>  bool icmp_ping_timer(const struct ctx *c, const struct icmp_ping_flow *pingf,
> diff --git a/udp_flow.h b/udp_flow.h
> index 9a1b059..9cb79a0 100644
> --- a/udp_flow.h
> +++ b/udp_flow.h
> @@ -12,6 +12,7 @@
>   * @f:		Generic flow information
>   * @closed:	Flow is already closed
>   * @ts:		Activity timestamp
> + * @ts_storage:	Pad @ts to 64-bit storage to keep state migration sane
>   * @s:		Socket fd (or -1) for each side of the flow
>   */
>  struct udp_flow {
> @@ -19,7 +20,10 @@ struct udp_flow {
>  	struct flow_common f;
>  
>  	bool closed :1;
> -	time_t ts;
> +	union {
> +		time_t ts;
> +		uint64_t ts_storage;
> +	};
>  	int s[SIDES];
>  };
>  

-- 
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

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]