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iscsi-target: Perform release of acknowledged tags from RX context

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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>
This commit is contained in:
Nicholas Bellinger 2013-10-03 13:56:14 -07:00
parent e255a28598
commit f56cbbb4b5
1 changed files with 9 additions and 4 deletions
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13
drivers/target/iscsi/iscsi_target.c
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@ -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)