Date:   Mon, 18 Jul 2022 18:28:34 -0700
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dmitry Bogdanov <d.bogdanov@...ro.com>
Cc:     linux-scsi@...r.kernel.org, target-devel@...r.kernel.org
Subject: [PATCH v2 24/25] usb: gadget: f_tcm: Check overlapped command

If there's an overlapped command tag, cancel the command and respond
with RC_OVERLAPPED_TAG to host.

Signed-off-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
---
 Changes in v2:
 - New patch. It was part of TASK MANAGEMENT change.
 - Directly respond to host on overlapped tag instead of reporting to target
   core.

 drivers/usb/gadget/function/f_tcm.c | 75 ++++++++++++++++++++++++++++-
 1 file changed, 73 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c
index 8b99ee07df87..dfa3e7c043a3 100644
--- a/drivers/usb/gadget/function/f_tcm.c
+++ b/drivers/usb/gadget/function/f_tcm.c
@@ -692,6 +692,15 @@ static void uasp_status_data_cmpl(struct usb_ep *ep, struct usb_request *req)
 		break;
 
 	case UASP_QUEUE_COMMAND:
+		/*
+		 * Overlapped command detected and cancelled.
+		 * So send overlapped attempted status.
+		 */
+		if (cmd->tmr_rsp == RC_OVERLAPPED_TAG &&
+		    req->status == -ECONNRESET) {
+			uasp_send_tm_response(cmd);
+			return;
+		}
 
 		stream->cmd = NULL;
 
@@ -700,7 +709,8 @@ static void uasp_status_data_cmpl(struct usb_ep *ep, struct usb_request *req)
 		 * bitmap index. This is for the cases where f_tcm handles
 		 * status response instead of the target core.
 		 */
-		if (cmd->tmr_rsp != RC_RESPONSE_UNKNOWN) {
+		if (cmd->tmr_rsp != RC_OVERLAPPED_TAG &&
+		    cmd->tmr_rsp != RC_RESPONSE_UNKNOWN) {
 			struct se_session *se_sess;
 
 			se_sess = fu->tpg->tpg_nexus->tvn_se_sess;
@@ -1080,6 +1090,14 @@ static void usbg_data_write_cmpl(struct usb_ep *ep, struct usb_request *req)
 
 cleanup:
 	target_put_sess_cmd(se_cmd);
+
+	/* Command was aborted due to overlapped tag */
+	if (cmd->state == UASP_QUEUE_COMMAND &&
+	    cmd->tmr_rsp == RC_OVERLAPPED_TAG) {
+		uasp_send_tm_response(cmd);
+		return;
+	}
+
 	transport_send_check_condition_and_sense(se_cmd,
 			TCM_CHECK_CONDITION_ABORT_CMD, 0);
 }
@@ -1148,9 +1166,10 @@ static int usbg_send_read_response(struct se_cmd *se_cmd)
 		return uasp_send_read_response(cmd);
 }
 
+static void usbg_aborted_task(struct se_cmd *se_cmd);
+
 static void usbg_submit_tmr(struct usbg_cmd *cmd)
 {
-	struct usbg_cmd *cmd = container_of(work, struct usbg_cmd, work);
 	struct se_session *se_sess;
 	struct se_cmd *se_cmd;
 	int flags = TARGET_SCF_ACK_KREF;
@@ -1214,6 +1233,51 @@ static void usbg_cmd_work(struct work_struct *work)
 	return;
 
 skip:
+	if (cmd->tmr_rsp == RC_OVERLAPPED_TAG) {
+		struct se_session *se_sess;
+		struct uas_stream *stream;
+
+		se_sess = cmd->fu->tpg->tpg_nexus->tvn_se_sess;
+		stream = uasp_get_stream_by_tag(cmd->fu, cmd->tag);
+
+		/*
+		 * There's no guarantee of a matching completion order between
+		 * different endpoints. i.e. The device may receive a new (CDB)
+		 * command request completion of the command endpoint before it
+		 * gets notified of the previous command status completion from
+		 * a status endpoint. The driver still needs to detect
+		 * misbehaving host and respond with an overlap command tag. To
+		 * prevent false overlapped tag failure, give the active and
+		 * matching stream id a short time (1ms) to complete before
+		 * respond with overlapped command failure.
+		 */
+		msleep(1);
+
+		/* If the stream is completed, retry the command. */
+		if (!stream->cmd) {
+			usbg_submit_command(cmd->fu, cmd->req);
+			return;
+		}
+
+		/*
+		 * The command isn't submitted to the target core, so we're safe
+		 * to remove the bitmap index from the session tag pool.
+		 */
+		sbitmap_queue_clear(&se_sess->sess_tag_pool,
+				    cmd->se_cmd.map_tag,
+				    cmd->se_cmd.map_cpu);
+
+		/*
+		 * Overlap command tag detected. Cancel any pending transfer of
+		 * the command submitted to target core.
+		 */
+		stream->cmd->tmr_rsp = RC_OVERLAPPED_TAG;
+		usbg_aborted_task(&stream->cmd->se_cmd);
+
+		/* Send the response after the transfer is aborted. */
+		return;
+	}
+
 	uasp_send_tm_response(cmd);
 }
 
@@ -1282,6 +1346,13 @@ static int usbg_submit_command(struct f_uas *fu, struct usb_request *req)
 		goto skip;
 	}
 
+	stream = uasp_get_stream_by_tag(fu, scsi_tag);
+	if (stream->cmd) {
+		pr_err("Command tag %d overlapped\n", scsi_tag);
+		cmd->tmr_rsp = RC_OVERLAPPED_TAG;
+		goto skip;
+	}
+
 	stream->cmd = cmd;
 
 	if (iu->iu_id == IU_ID_TASK_MGMT) {
-- 
2.28.0

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