Reviews pretty please..?
On Sat, 2017-06-03 at 21:32 +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
>
> This patch fixes a BUG() in iscsit_close_session() that could be
> triggered when iscsit_logout_post_handler() execution from within
> tx thread context was not run for more than SECONDS_FOR_LOGOUT_COMP
> (15 seconds), and the TCP connection didn't already close before
> then forcing tx thread context to automatically exit.
>
> This would manifest itself during explicit logout as:
>
> [33206.974254] 1 connection(s) still exist for iSCSI session to iqn.1993-08.org.debian:01:3f5523242179
> [33206.980184] INFO: NMI handler (kgdb_nmi_handler) took too long to run: 2100.772 msecs
> [33209.078643] ------------[ cut here ]------------
> [33209.078646] kernel BUG at drivers/target/iscsi/iscsi_target.c:4346!
>
> Normally when explicit logout attempt fails, the tx thread context
> exits and iscsit_close_connection() from rx thread context does the
> extra cleanup once it detects conn->conn_logout_remove has not been
> cleared by the logout type specific post handlers.
>
> To address this special case, if the logout post handler in tx thread
> context detects conn->tx_thread_active has already been cleared, simply
> return and exit in order for existing iscsit_close_connection()
> logic from rx thread context do failed logout cleanup.
>
> Reported-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
> Cc: Mike Christie <mchristi@xxxxxxxxxx>
> Cc: Hannes Reinecke <hare@xxxxxxx>
> Cc: Sagi Grimberg <sagig@xxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # 3.14+
> Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
> ---
> drivers/target/iscsi/iscsi_target.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
> index 0d8f815..c025451 100644
> --- a/drivers/target/iscsi/iscsi_target.c
> +++ b/drivers/target/iscsi/iscsi_target.c
> @@ -4423,8 +4423,11 @@ static void iscsit_logout_post_handler_closesession(
> * always sleep waiting for RX/TX thread shutdown to complete
> * within iscsit_close_connection().
> */
> - if (!conn->conn_transport->rdma_shutdown)
> + if (!conn->conn_transport->rdma_shutdown) {
> sleep = cmpxchg(&conn->tx_thread_active, true, false);
> + if (!sleep)
> + return;
> + }
>
> atomic_set(&conn->conn_logout_remove, 0);
> complete(&conn->conn_logout_comp);
> @@ -4440,8 +4443,11 @@ static void iscsit_logout_post_handler_samecid(
> {
> int sleep = 1;
>
> - if (!conn->conn_transport->rdma_shutdown)
> + if (!conn->conn_transport->rdma_shutdown) {
> sleep = cmpxchg(&conn->tx_thread_active, true, false);
> + if (!sleep)
> + return;
> + }
>
> atomic_set(&conn->conn_logout_remove, 0);
> complete(&conn->conn_logout_comp);
