[PATCH net v2 1/2] net/smc: stop killed, freed and out_of_sync sharing a byte

[Hidayath Khan <hidayath@linux.ibm.com>]

The three connection state flags are single-bit bitfields, so they occupy
one byte of struct smc_connection and every store to one is a
read-modify-write of the other two:

    u8  killed : 1;
    u8  freed : 1;
    u8  out_of_sync : 1;

They are not written under a common lock. smc_cdc_msg_validate() sets
out_of_sync from the receive tasklet, while smc_conn_kill() sets killed
from process context under lock_sock(), and the receive path does not defer
to the backlog when the socket is owned -- smc_cdc_msg_recv() takes only
bh_lock_sock().

Give each flag its own byte so a store no longer touches its neighbours.
All readers test them as booleans and are unchanged. struct smc_connection
grows by two bytes.

Fixes: b286a0651e44 ("net/smc: handle incoming CDC validation message")
Cc: stable@vger.kernel.org
Reviewed-by: Mahanta Jambigi <mjambigi@linux.ibm.com>
Signed-off-by: Hidayath Khan <hidayath@linux.ibm.com>
---
New in v2.

 net/smc/smc.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/smc/smc.h b/net/smc/smc.h
index 52145df83f6e..427b6d63b993 100644
--- a/net/smc/smc.h
+++ b/net/smc/smc.h
@@ -277,9 +277,9 @@ struct smc_connection {
 						 * 0 for SMC-R, 32 for SMC-D
 						 */
 	u64			peer_token;	/* SMC-D token of peer */
-	u8			killed : 1;	/* abnormal termination */
-	u8			freed : 1;	/* normal termination */
-	u8			out_of_sync : 1; /* out of sync with peer */
+	u8			killed;		/* abnormal termination */
+	u8			freed;		/* normal termination */
+	u8			out_of_sync;	/* out of sync with peer */
 };
 
 struct smc_sock {				/* smc sock container */
-- 
2.52.0