netdev - RE: [PATCH net] inet: properly align icsk_ca

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Date:	Tue, 19 May 2015 02:36:48 +0000
From:	"Du, Fan" <fan.du@...el.com>
To:	Eric Dumazet <eric.dumazet@...il.com>,
	Stephen Hemminger <stephen@...workplumber.org>,
	David Miller <davem@...emloft.net>
CC:	Kenneth Klette Jonassen <kennetkl@....uio.no>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	David Hayes <davihay@....uio.no>,
	Yuchung Cheng <ycheng@...gle.com>,
	Andreas Petlund <apetlund@...ula.no>,
	"Du, Fan" <fan.du@...el.com>
Subject: RE: [PATCH net] inet: properly align icsk_ca_priv



>-----Original Message-----
>From: Eric Dumazet [mailto:eric.dumazet@...il.com]
>Sent: Tuesday, May 19, 2015 8:06 AM
>To: Stephen Hemminger; Du, Fan; David Miller
>Cc: Kenneth Klette Jonassen; netdev@...r.kernel.org; David Hayes; Yuchung
>Cheng; Andreas Petlund
>Subject: [PATCH net] inet: properly align icsk_ca_priv
>
>From: Eric Dumazet <edumazet@...gle.com>
>
>tcp_illinois and upcoming tcp_cdg require 64bit alignment of
>icsk_ca_priv
>
>x86 does not care, but other architectures might.
>
>Fixes: 05cbc0db03e82 ("ipv4: Create probe timer for tcp PMTU as per RFC4821")

If you mean this:
Before commit 05cbc0db03e82 ("ipv4: Create probe timer for tcp PMTU as per RFC4821")
        struct {
                int                enabled;              /*  1152     4 */
                int                search_high;          /*  1156     4 */
                int                search_low;           /*  1160     4 */
                int                probe_size;           /*  1164     4 */
        } icsk_mtup;                                     /*  1152    16 */
        u32                        icsk_ca_priv[16];     /*  1168    64 */      <-- 1168/6 = 146
        /* --- cacheline 19 boundary (1216 bytes) was 16 bytes ago --- */
        u32                        icsk_user_timeout;    /*  1232     4 */

        /* size: 1240, cachelines: 20, members: 23 */
        /* padding: 4 */
        /* last cacheline: 24 bytes */
};


After commit 05cbc0db03e82 ("ipv4: Create probe timer for tcp PMTU as per RFC4821")

        struct {
                int                enabled;              /*  1152     4 */
                int                search_high;          /*  1156     4 */
                int                search_low;           /*  1160     4 */
                int                probe_size;           /*  1164     4 */
                u32                probe_timestamp;      /*  1168     4 */
        } icsk_mtup;                                     /*  1152    20 */
        u32                        icsk_ca_priv[16];     /*  1172    64 */        <-- 1172/6 = 146.5
        /* --- cacheline 19 boundary (1216 bytes) was 20 bytes ago --- */
        u32                        icsk_user_timeout;    /*  1236     4 */

        /* size: 1240, cachelines: 20, members: 23 */
        /* last cacheline: 24 bytes */
};

Acked-by: Fan Du <fan.du@...el.com>


>Signed-off-by: Eric Dumazet <edumazet@...gle.com>
>Cc: Fan Du <fan.du@...el.com>
>---
> include/net/inet_connection_sock.h |    5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
>diff --git a/include/net/inet_connection_sock.h
>b/include/net/inet_connection_sock.h
>index
>48a8158235874b1625c65651b0bd92eedd999fe5..497bc14cdb85f4f8b33da8fbe7
>aba9d491df50e2 100644
>--- a/include/net/inet_connection_sock.h
>+++ b/include/net/inet_connection_sock.h
>@@ -129,9 +129,10 @@ struct inet_connection_sock {
>
> 		u32		  probe_timestamp;
> 	} icsk_mtup;
>-	u32			  icsk_ca_priv[16];
> 	u32			  icsk_user_timeout;
>-#define ICSK_CA_PRIV_SIZE	(16 * sizeof(u32))
>+
>+	u64			  icsk_ca_priv[64 / sizeof(u64)];
>+#define ICSK_CA_PRIV_SIZE      (8 * sizeof(u64))
> };
>
> #define ICSK_TIME_RETRANS	1	/* Retransmit timer */
>