[PATCH net-next 1/4] scsi_tcp: block BH in TCP callbacks

[Eric Dumazet]

iscsi_sw_tcp_data_ready() and iscsi_sw_tcp_state_change() were
using read_lock(&sk->sk_callback_lock) which is fine if caller
disabled BH.

TCP stack no longer has this requirement and can run from
process context.

Use read_lock_bh() variant to restore previous assumption.

Ideally this code could use RCU instead...

Fixes: 5413d1babe8f ("net: do not block BH while processing socket backlog")
Fixes: d41a69f1d390 ("tcp: make tcp_sendmsg() aware of socket backlog")
Signed-off-by: Eric Dumazet <eduma...@google.com>
Cc: Mike Christie <micha...@cs.wisc.edu>
Cc: Venkatesh Srinivas <venkate...@google.com>
---
 drivers/scsi/iscsi_tcp.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 2e4c82f8329c..ace4f1f41b8e 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -131,10 +131,10 @@ static void iscsi_sw_tcp_data_ready(struct sock *sk)
        struct iscsi_tcp_conn *tcp_conn;
        read_descriptor_t rd_desc;
 
-       read_lock(&sk->sk_callback_lock);
+       read_lock_bh(&sk->sk_callback_lock);
        conn = sk->sk_user_data;
        if (!conn) {
-               read_unlock(&sk->sk_callback_lock);
+               read_unlock_bh(&sk->sk_callback_lock);
                return;
        }
        tcp_conn = conn->dd_data;
@@ -154,7 +154,7 @@ static void iscsi_sw_tcp_data_ready(struct sock *sk)
        /* If we had to (atomically) map a highmem page,
         * unmap it now. */
        iscsi_tcp_segment_unmap(&tcp_conn->in.segment);
-       read_unlock(&sk->sk_callback_lock);
+       read_unlock_bh(&sk->sk_callback_lock);
 }
 
 static void iscsi_sw_tcp_state_change(struct sock *sk)
@@ -165,10 +165,10 @@ static void iscsi_sw_tcp_state_change(struct sock *sk)
        struct iscsi_session *session;
        void (*old_state_change)(struct sock *);
 
-       read_lock(&sk->sk_callback_lock);
+       read_lock_bh(&sk->sk_callback_lock);
        conn = sk->sk_user_data;
        if (!conn) {
-               read_unlock(&sk->sk_callback_lock);
+               read_unlock_bh(&sk->sk_callback_lock);
                return;
        }
        session = conn->session;
@@ -179,7 +179,7 @@ static void iscsi_sw_tcp_state_change(struct sock *sk)
        tcp_sw_conn = tcp_conn->dd_data;
        old_state_change = tcp_sw_conn->old_state_change;
 
-       read_unlock(&sk->sk_callback_lock);
+       read_unlock_bh(&sk->sk_callback_lock);
 
        old_state_change(sk);
 }
-- 
2.8.0.rc3.226.g39d4020