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[net-next,2/5] net/smc: fix structure size

Message ID 20180221113235.46702-3-ubraun@linux.vnet.ibm.com
State Changes Requested, archived
Delegated to: David Miller
Headers show
Series net/smc: fixes 2018-02-21 | expand

Commit Message

Ursula Braun Feb. 21, 2018, 11:32 a.m. UTC 
From: Karsten Graul <kgraul@linux.vnet.ibm.com>

The struct smc_cdc_msg must be defined as packed, so the size is 44 bytes.
And change the structure size check, so sizeof is checked.

Signed-off-by: Karsten Graul <kgraul@linux.vnet.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
---
 net/smc/smc_cdc.c | 2 +-
 net/smc/smc_cdc.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Comments

David Miller Feb. 22, 2018, 7:10 p.m. UTC | #1 
From: Ursula Braun <ubraun@linux.vnet.ibm.com>
Date: Wed, 21 Feb 2018 12:32:32 +0100

> diff --git a/net/smc/smc_cdc.h b/net/smc/smc_cdc.h
> index ab240b37ad11..d2012fd22100 100644
> --- a/net/smc/smc_cdc.h
> +++ b/net/smc/smc_cdc.h
> @@ -48,7 +48,7 @@ struct smc_cdc_msg {
>  	struct smc_cdc_producer_flags	prod_flags;
>  	struct smc_cdc_conn_state_flags	conn_state_flags;
>  	u8				reserved[18];
> -} __aligned(8);
> +} __packed;					/* format defined in RFC7609 */

Hold on, __packed should only be used as the absolute last possible
option to fix structure layout problems.

Also, a sub-structure of smc_cdc_msg, union smc_cdc_cursor, is still
marked with __aligned(8).  That makes no sense at all.

Please fix this without using __packed, as __packed has a severe
detrimental effect on code generation for accessing such structure
on several cpu architectures.

Also, if this these are legitimate bug fixes you should target those
at 'net' not 'net-next'.

Thank you.
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Patch

diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
index 3cd086e5bd28..9b28e64c50d4 100644
--- a/net/smc/smc_cdc.c
+++ b/net/smc/smc_cdc.c
@@ -82,7 +82,7 @@  static inline void smc_cdc_add_pending_send(struct smc_connection *conn,
 		sizeof(struct smc_cdc_msg) > SMC_WR_BUF_SIZE,
 		"must increase SMC_WR_BUF_SIZE to at least sizeof(struct smc_cdc_msg)");
 	BUILD_BUG_ON_MSG(
-		offsetof(struct smc_cdc_msg, reserved) > SMC_WR_TX_SIZE,
+		sizeof(struct smc_cdc_msg) != SMC_WR_TX_SIZE,
 		"must adapt SMC_WR_TX_SIZE to sizeof(struct smc_cdc_msg); if not all smc_wr upper layer protocols use the same message size any more, must start to set link->wr_tx_sges[i].length on each individual smc_wr_tx_send()");
 	BUILD_BUG_ON_MSG(
 		sizeof(struct smc_cdc_tx_pend) > SMC_WR_TX_PEND_PRIV_SIZE,
diff --git a/net/smc/smc_cdc.h b/net/smc/smc_cdc.h
index ab240b37ad11..d2012fd22100 100644
--- a/net/smc/smc_cdc.h
+++ b/net/smc/smc_cdc.h
@@ -48,7 +48,7 @@  struct smc_cdc_msg {
 	struct smc_cdc_producer_flags	prod_flags;
 	struct smc_cdc_conn_state_flags	conn_state_flags;
 	u8				reserved[18];
-} __aligned(8);
+} __packed;					/* format defined in RFC7609 */
 
 static inline bool smc_cdc_rxed_any_close(struct smc_connection *conn)
 {