[PATCH v2 21/25] usb: gadget: f_tcm: Get stream by tag

Thinh Nguyen
2022-07-19T02:16:29Z

In preparation for TASK MANAGEMENT handling of overlapped command,
implement uasp_get_stream_by_tag() to find the active stream/command
based on a given tag.

For simplicity, we use mod operation to quickly find an in-progress
matching command tag to check for overlapped command. The assumption is
that the UASP class driver will limit to using tag id from 1 to
USBG_NUM_CMDS. This is based on observation from the Windows and Linux
UASP storage class driver behavior. If an unusual UASP class driver uses
a tag greater than USBG_NUM_CMDS, then this method may no longer work
due to possible stream id collision. In that case, we need to use a
proper algorithm to fetch the stream (or simply walk through all active
streams to check for overlap).

Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
Changes in v2:
- Splitted from TASK MANAGEMENT change

drivers/usb/gadget/function/f_tcm.c | 30 ++++++++++++++++++++++-------
1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c
index 084143213176..a10e74290664 100644
--- a/drivers/usb/gadget/function/f_tcm.c
+++ b/drivers/usb/gadget/function/f_tcm.c
@@ -506,6 +506,22 @@ static void uasp_cleanup_old_alt(struct f_uas *fu)
uasp_free_cmdreq(fu);
}

+static struct uas_stream *uasp_get_stream_by_tag(struct f_uas *fu, u16 tag)
+{
+ /*
+ * For simplicity, we use mod operation to quickly find an in-progress
+ * matching command tag to check for overlapped command. The assumption
+ * is that the UASP class driver will limit to using tag id from 1 to
+ * USBG_NUM_CMDS. This is based on observation from the Windows and
+ * Linux UASP storage class driver behavior. If an unusual UASP class
+ * driver uses a tag greater than USBG_NUM_CMDS, then this method may no
+ * longer work due to possible stream id collision. In that case, we
+ * need to use a proper algorithm to fetch the stream (or simply walk
+ * through all active streams to check for overlap).
+ */
+ return &fu->stream[tag % USBG_NUM_CMDS];
+}
+
static void uasp_status_data_cmpl(struct usb_ep *ep, struct usb_request *req);

static int uasp_prepare_r_request(struct usbg_cmd *cmd)
@@ -513,7 +529,7 @@ static int uasp_prepare_r_request(struct usbg_cmd *cmd)
struct se_cmd *se_cmd = &cmd->se_cmd;
struct f_uas *fu = cmd->fu;
struct usb_gadget *gadget = fuas_to_gadget(fu);
- struct uas_stream *stream = cmd->stream;
+ struct uas_stream *stream = uasp_get_stream_by_tag(fu, cmd->tag);

if (!gadget->sg_supported) {
cmd->data_buf = kmalloc(se_cmd->data_length, GFP_ATOMIC);
@@ -546,7 +562,7 @@ static void uasp_prepare_status(struct usbg_cmd *cmd)
{
struct se_cmd *se_cmd = &cmd->se_cmd;
struct sense_iu *iu = &cmd->sense_iu;
- struct uas_stream *stream = cmd->stream;
+ struct uas_stream *stream = uasp_get_stream_by_tag(cmd->fu, cmd->tag);

cmd->state = UASP_QUEUE_COMMAND;
iu->iu_id = IU_ID_STATUS;
@@ -568,8 +584,8 @@ static void uasp_prepare_status(struct usbg_cmd *cmd)
static void uasp_status_data_cmpl(struct usb_ep *ep, struct usb_request *req)
{
struct usbg_cmd *cmd = req->context;
- struct uas_stream *stream = cmd->stream;
struct f_uas *fu = cmd->fu;
+ struct uas_stream *stream = uasp_get_stream_by_tag(fu, cmd->tag);
int ret;

if (req->status == -ESHUTDOWN)
@@ -620,7 +636,7 @@ static void uasp_status_data_cmpl(struct usb_ep *ep, struct usb_request *req)
static int uasp_send_status_response(struct usbg_cmd *cmd)
{
struct f_uas *fu = cmd->fu;
- struct uas_stream *stream = cmd->stream;
+ struct uas_stream *stream = uasp_get_stream_by_tag(fu, cmd->tag);
struct sense_iu *iu = &cmd->sense_iu;

iu->tag = cpu_to_be16(cmd->tag);
@@ -632,7 +648,7 @@ static int uasp_send_status_response(struct usbg_cmd *cmd)
static int uasp_send_read_response(struct usbg_cmd *cmd)
{
struct f_uas *fu = cmd->fu;
- struct uas_stream *stream = cmd->stream;
+ struct uas_stream *stream = uasp_get_stream_by_tag(fu, cmd->tag);
struct sense_iu *iu = &cmd->sense_iu;
int ret;

@@ -675,7 +691,7 @@ static int uasp_send_read_response(struct usbg_cmd *cmd)
static int uasp_send_write_request(struct usbg_cmd *cmd)
{
struct f_uas *fu = cmd->fu;
- struct uas_stream *stream = cmd->stream;
+ struct uas_stream *stream = uasp_get_stream_by_tag(fu, cmd->tag);
struct sense_iu *iu = &cmd->sense_iu;
int ret;

@@ -1285,7 +1301,7 @@ static void usbg_aborted_task(struct se_cmd *se_cmd)
{
struct usbg_cmd *cmd = container_of(se_cmd, struct usbg_cmd, se_cmd);
struct f_uas *fu = cmd->fu;
- struct uas_stream *stream = cmd->stream;
+ struct uas_stream *stream = uasp_get_stream_by_tag(fu, cmd->tag);
int ret = 0;

if (stream->req_out->status == -EINPROGRESS)
--
2.28.0