From f56cbbb4b5871e5bc2838ddeeba5b29debc2a734 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger <nab@linux-iscsi.org> Date: Thu, 3 Oct 2013 13:56:14 -0700 Subject: [PATCH] iscsi-target: Perform release of acknowledged tags from RX context This patch converts iscsit_ack_from_expstatsn() to populate a local ack_list of commands, and call iscsit_free_cmd() directly from RX thread context, instead of using iscsit_add_cmd_to_immediate_queue() to queue the acknowledged commands to be released from TX thread context. It is helpful to release the acknowledge commands as quickly as possible, along with the associated percpu_ida tags, in order to prevent percpu_ida_alloc() from having to steal tags from other CPUs while waiting for iscsit_free_cmd() to happen from TX thread context. Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> --- drivers/target/iscsi/iscsi_target.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c index 35b61f7d6c63..38e44b9abf0f 100644 --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -753,7 +753,8 @@ static void iscsit_unmap_iovec(struct iscsi_cmd *cmd) static void iscsit_ack_from_expstatsn(struct iscsi_conn *conn, u32 exp_statsn) { - struct iscsi_cmd *cmd; + LIST_HEAD(ack_list); + struct iscsi_cmd *cmd, *cmd_p; conn->exp_statsn = exp_statsn; @@ -761,19 +762,23 @@ static void iscsit_ack_from_expstatsn(struct iscsi_conn *conn, u32 exp_statsn) return; spin_lock_bh(&conn->cmd_lock); - list_for_each_entry(cmd, &conn->conn_cmd_list, i_conn_node) { + list_for_each_entry_safe(cmd, cmd_p, &conn->conn_cmd_list, i_conn_node) { spin_lock(&cmd->istate_lock); if ((cmd->i_state == ISTATE_SENT_STATUS) && iscsi_sna_lt(cmd->stat_sn, exp_statsn)) { cmd->i_state = ISTATE_REMOVE; spin_unlock(&cmd->istate_lock); - iscsit_add_cmd_to_immediate_queue(cmd, conn, - cmd->i_state); + list_move_tail(&cmd->i_conn_node, &ack_list); continue; } spin_unlock(&cmd->istate_lock); } spin_unlock_bh(&conn->cmd_lock); + + list_for_each_entry_safe(cmd, cmd_p, &ack_list, i_conn_node) { + list_del(&cmd->i_conn_node); + iscsit_free_cmd(cmd, false); + } } static int iscsit_allocate_iovecs(struct iscsi_cmd *cmd) -- 2.30.2