Greetings all, This patch is made against lio-core-2.6.git/master and tested on v2.6.28. The lio-core-2.6.git tree can be found at: http://git.kernel.org/?p=linux/kernel/git/nab/lio-core-2.6.git;a=summary Thanks, --nab >From 6fdadad6ac238cd1a5992c07de7acac0f44a7afb Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> Date: Sat, 10 Jan 2009 16:50:16 -0800 Subject: [PATCH] [LIO-Target]: Fix explict iSCSI Logout + iSCSI connection failure corner case While handling a iSCSI Logout with reason_code CLOSESESSION or a same CID CLOSECONNECTION request, there was a scenario observed where if the iSCSI connection where the Logout PDU was received on was to fail *before* the iSCSI TX thread for said connection could call iscsi_send_logout_response(), iscsi_close_connection() was being hung indefinately in iscsi_check_conn_usage_count() waiting for a zero iscsi_conn_t reference count. This patch moves up the iscsi_inc_conn_usage_count() and iscsi_inc_session_usage_count() calls to iscsi_logout_closesession() and iscsi_logout_closeconnection() in iSCSI RX Thread context. This logic had previously been located in iscsi_send_logout_response() in iSCSI TX Thread context, which in the case of iSCSI connection failure would cause the following logic to trigger in iscsi_target.c:iscsi_close_connection(): if (atomic_read(&conn->conn_logout_remove)) { if (conn->conn_logout_reason == CLOSESESSION) { iscsi_dec_conn_usage_count(conn); iscsi_dec_session_usage_count(sess); } if (conn->conn_logout_reason == CLOSECONNECTION) iscsi_dec_conn_usage_count(conn); atomic_set(&conn->conn_logout_remove, 0); atomic_set(&sess->session_reinstatement, 0); atomic_set(&sess->session_fall_back_to_erl0, 1); } This would incorrect call iscsi_dec_conn_usage_count() and iscsi_dec_session_usage_count() (depending on logout_reason), even though the iSCSI TX thread context code had not reached iscsi_send_logout_response() to actually increment the iscsi_conn_t and iscsi_session_t reference counts. This was because iscsi_conn_t->conn_logout_remove is set in iscsi_logout_closesession() and iscsi_logout_closeconnection(). Tested with SC/S CLOSECONNECTION failure and MC/S same CID CLOSECONNECTION + iSCSI connection failure cases on v2.6.28. Signed-off-by: Nicholas A. Bellinger <nab@xxxxxxxxxxxxxxx> --- drivers/lio-core/iscsi_target.c | 32 +++++++++++++++++--------------- 1 files changed, 17 insertions(+), 15 deletions(-) diff --git a/drivers/lio-core/iscsi_target.c b/drivers/lio-core/iscsi_target.c index 019fb08..8f572af 100644 --- a/drivers/lio-core/iscsi_target.c +++ b/drivers/lio-core/iscsi_target.c @@ -2684,16 +2684,17 @@ extern int iscsi_logout_closesession (iscsi_cmd_t *cmd, iscsi_conn_t *conn) atomic_set(&sess->session_logout, 1); atomic_set(&conn->conn_logout_remove, 1); conn->conn_logout_reason = CLOSESESSION; + + iscsi_inc_conn_usage_count(conn); + iscsi_inc_session_usage_count(sess); spin_lock_bh(&sess->conn_lock); for (conn_p = sess->conn_head; conn_p; conn_p = conn_p->next) { if (conn_p->conn_state != TARG_CONN_STATE_LOGGED_IN) continue; - iscsi_inc_conn_usage_count(conn_p); TRACE(TRACE_STATE, "Moving to TARG_CONN_STATE_IN_LOGOUT.\n"); conn_p->conn_state = TARG_CONN_STATE_IN_LOGOUT; - iscsi_dec_conn_usage_count(conn_p); } spin_unlock_bh(&sess->conn_lock); @@ -2722,8 +2723,11 @@ extern int iscsi_logout_closeconnection (iscsi_cmd_t *cmd, iscsi_conn_t *conn) spin_lock_bh(&conn->state_lock); TRACE(TRACE_STATE, "Moving to TARG_CONN_STATE_IN_LOGOUT.\n"); conn->conn_state = TARG_CONN_STATE_IN_LOGOUT; + atomic_set(&conn->conn_logout_remove, 1); conn->conn_logout_reason = CLOSECONNECTION; + iscsi_inc_conn_usage_count(conn); + spin_unlock_bh(&conn->state_lock); } else { /* @@ -3503,24 +3507,22 @@ static inline int iscsi_send_logout_response ( TRACE(TRACE_ISCSI, "iSCSI session logout successful, setting" " logout response to CONNORSESSCLOSEDSUCCESSFULLY.\n"); cmd->logout_response = CONNORSESSCLOSEDSUCCESSFULLY; - iscsi_inc_conn_usage_count(conn); - iscsi_inc_session_usage_count(sess); break; case CLOSECONNECTION: if (cmd->logout_response == CIDNOTFOUND) break; + /* + * For CLOSECONNECTION logout requests carrying + * a matching logout CID -> local CID, the reference + * for the local CID will have been incremented in + * iscsi_logout_closeconnection(). + * + * For CLOSECONNECTION logout requests carrying + * a different CID than the connection it arrived + * on, the connection responding to cmd->logout_cid + * is stopped in iscsi_logout_post_handler_diffcid(). + */ - if (conn->cid == cmd->logout_cid) - iscsi_inc_conn_usage_count(conn); - else { - /* - * For CLOSECONNECTION logout requests carrying - * a different CID than the connection it arrived - * on, the connection responding to cmd->logout_cid - * is stopped in iscsi_logout_post_handler_diffcid(). - */ - do {} while(0); - } TRACE(TRACE_ISCSI, "iSCSI CID: %hu logout on CID: %hu" " successful.\n", cmd->logout_cid, conn->cid); cmd->logout_response = CONNORSESSCLOSEDSUCCESSFULLY; -- 1.5.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
