From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maurizio Lombardi Date: Mon, 16 Nov 2020 13:38:24 +0000 Subject: Re: [PATCH] iscsi target: fix cmd abort fabric stop race Message-Id: <4c55f623-9347-ead7-0f5b-6cf1f7687584@redhat.com> List-Id: References: <1605318378-9269-1-git-send-email-michael.christie@oracle.com> In-Reply-To: <1605318378-9269-1-git-send-email-michael.christie@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Mike Christie , martin.petersen@oracle.com, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org Dne 14. 11. 20 v 2:46 Mike Christie napsal(a): > Maurizio Lombardi found a race where the abort > and cmd stop paths can race as follows: > > 1. thread1 runs iscsit_release_commands_from_conn and sets > CMD_T_FABRIC_STOP. > 2. thread2 runs iscsit_aborted_task and then does __iscsit_free_cmd. It > then returns from the aborted_task callout and we finish > target_handle_abort and do: > > target_handle_abort -> transport_cmd_check_stop_to_fabric -> > lio_check_stop_free -> target_put_sess_cmd > > The cmd is now freed. > 3. thread1 now finishes iscsit_release_commands_from_conn and runs > iscsit_free_cmd while accessing a command we just released. > > In __target_check_io_state we check for CMD_T_FABRIC_STOP and set the > CMD_T_ABORTED if the driver is not cleaning up the cmd because of > a session shutdown. However, iscsit_release_commands_from_conn only > sets the CMD_T_FABRIC_STOP and does not check to see if the abort path > has claimed completion ownership of the command. > > This adds a check in iscsit_release_commands_from_conn so only the > abort or fabric stop path cleanup the command. > > Signed-off-by: Mike Christie > > --- > drivers/target/iscsi/iscsi_target.c | 17 +++++++++++++---- > 1 file changed, 13 insertions(+), 4 deletions(-) > > diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c > index f77e5ee..518fac4 100644 > --- a/drivers/target/iscsi/iscsi_target.c > +++ b/drivers/target/iscsi/iscsi_target.c > @@ -483,8 +483,7 @@ int iscsit_queue_rsp(struct iscsi_conn *conn, struct iscsi_cmd *cmd) > void iscsit_aborted_task(struct iscsi_conn *conn, struct iscsi_cmd *cmd) > { > spin_lock_bh(&conn->cmd_lock); > - if (!list_empty(&cmd->i_conn_node) && > - !(cmd->se_cmd.transport_state & CMD_T_FABRIC_STOP)) > + if (!list_empty(&cmd->i_conn_node)) > list_del_init(&cmd->i_conn_node); > spin_unlock_bh(&conn->cmd_lock); > > @@ -4083,12 +4082,22 @@ static void iscsit_release_commands_from_conn(struct iscsi_conn *conn) > spin_lock_bh(&conn->cmd_lock); > list_splice_init(&conn->conn_cmd_list, &tmp_list); > > - list_for_each_entry(cmd, &tmp_list, i_conn_node) { > + list_for_each_entry_safe(cmd, cmd_tmp, &tmp_list, i_conn_node) { > struct se_cmd *se_cmd = &cmd->se_cmd; > > if (se_cmd->se_tfo != NULL) { > spin_lock_irq(&se_cmd->t_state_lock); > - se_cmd->transport_state |= CMD_T_FABRIC_STOP; > + if (se_cmd->transport_state & CMD_T_ABORTED) { > + /* > + * LIO's abort path owns the cleanup for this, > + * so put it back on the list and let > + * aborted_task handle it. > + */ > + list_move_tail(&cmd->i_conn_node, > + &conn->conn_cmd_list); > + } else { > + se_cmd->transport_state |= CMD_T_FABRIC_STOP; > + } > spin_unlock_irq(&se_cmd->t_state_lock); > } > } > Reviewed-by: Maurizio Lombardi