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Commit f56cbbb4 authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

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: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent e255a285

drivers/target/iscsi/iscsi_target.c

+9 −4
Original line number Diff line number Diff line
@@ -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)