[PATCH] usbip: add USBIP_URB_* URB transfer flags

From: Shuah Khan
Date: Tue Aug 16 2022 - 17:57:26 EST

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USBIP driver packs URB transfer flags in PDUs that are exchanged
between Server (usbip_host) and Clinet (vhci_hcd). URB_* flags
are internal to kernel and could change. Where as USBIP URB flags
exchanged in PDUs are USBIP user API must not change.

Add USBIP_URB* flags to make this an expclicit API and change the
client and server to map them. Details as follows:

Client tx path (USBIP_CMD_SUBMIT):
- Maps URB_* to USBIP_URB_* when it sends USBIP_CMD_SUBMIT packet.

Server rx path (USBIP_CMD_SUBMIT):
- Maps USBIP_URB_* to URB_* when it receives USBIP_CMD_SUBMIT packet.

Flags aren't included in USBIP_CMD_UNLINK and USBIP_RET_SUBMIT packets
and no special handling is needed for them in the following cases:

- Server rx path (USBIP_CMD_UNLINK)
- Client rx path & Server tx path (USBIP_RET_SUBMIT)

Update protocol documentation to reflect the change.

Suggested-by: Hongren Zenithal Zheng <i@xxxxxxxxxxx>
Suggested-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
---
Documentation/usb/usbip_protocol.rst | 11 ++--
drivers/usb/usbip/stub_rx.c | 8 ++-
drivers/usb/usbip/usbip_common.c | 95 +++++++++++++++++++++++++++-
drivers/usb/usbip/vhci_tx.c | 1 +
drivers/usb/usbip/vudc_rx.c | 1 +
include/uapi/linux/usbip.h | 40 ++++++++++++
6 files changed, 146 insertions(+), 10 deletions(-)

diff --git a/Documentation/usb/usbip_protocol.rst b/Documentation/usb/usbip_protocol.rst
index 0b8541fda4d8..1c5b1db86fd0 100644
--- a/Documentation/usb/usbip_protocol.rst
+++ b/Documentation/usb/usbip_protocol.rst
@@ -341,12 +341,13 @@ USBIP_CMD_SUBMIT:
+-----------+--------+---------------------------------------------------+
| 0x14 | 4 | transfer_flags: possible values depend on the |
| | | URB transfer_flags (refer to URB doc in |
+| | | include/uapi/linux/usbip.h and |
| | | Documentation/driver-api/usb/URB.rst) |
-| | | but with URB_NO_TRANSFER_DMA_MAP masked. Refer to |
-| | | function usbip_pack_cmd_submit and function |
-| | | tweak_transfer_flags in drivers/usb/usbip/ |
-| | | usbip_common.c. The following fields may also ref |
-| | | to function usbip_pack_cmd_submit and URB doc |
+| | | but with USBIP_URB_NO_TRANSFER_DMA_MAP masked. |
+| | | Refer to usbip_pack_cmd_submit() and |
+| | | tweak_transfer_flags() in drivers/usb/usbip/ |
+| | | usbip_common.c. The following fields may also |
+| | | refer to usbip_pack_cmd_submit() and URB doc |
+-----------+--------+---------------------------------------------------+
| 0x18 | 4 | transfer_buffer_length: |
| | | use URB transfer_buffer_length |
diff --git a/drivers/usb/usbip/stub_rx.c b/drivers/usb/usbip/stub_rx.c
index 5dd41e8215e0..638d33120f26 100644
--- a/drivers/usb/usbip/stub_rx.c
+++ b/drivers/usb/usbip/stub_rx.c
@@ -464,7 +464,7 @@ static void stub_recv_cmd_submit(struct stub_device *sdev,
int nents;
int num_urbs = 1;
int pipe = get_pipe(sdev, pdu);
- int use_sg = pdu->u.cmd_submit.transfer_flags & URB_DMA_MAP_SG;
+ int use_sg = pdu->u.cmd_submit.transfer_flags & USBIP_URB_DMA_MAP_SG;
int support_sg = 1;
int np = 0;
int ret, i;
@@ -514,7 +514,7 @@ static void stub_recv_cmd_submit(struct stub_device *sdev,
num_urbs = nents;
priv->completed_urbs = 0;
pdu->u.cmd_submit.transfer_flags &=
- ~URB_DMA_MAP_SG;
+ ~USBIP_URB_DMA_MAP_SG;
}
} else {
buffer = kzalloc(buf_len, GFP_KERNEL);
@@ -556,6 +556,7 @@ static void stub_recv_cmd_submit(struct stub_device *sdev,
return;
}

+ /* Unpack the pdu to an urb (map USBIP_URB_* to URB_* flags) */
usbip_pack_pdu(pdu, priv->urbs[0], USBIP_CMD_SUBMIT, 0);
} else {
for_each_sg(sgl, sg, nents, i) {
@@ -566,6 +567,9 @@ static void stub_recv_cmd_submit(struct stub_device *sdev,
if (!priv->urbs[i])
goto err_urb;

+ /* Unpack the pdu to an urb (map USBIP_URB_* to
+ * URB_* flags)
+ */
usbip_pack_pdu(pdu, priv->urbs[i], USBIP_CMD_SUBMIT, 0);
priv->urbs[i]->transfer_buffer = sg_virt(sg);
priv->urbs[i]->transfer_buffer_length = sg->length;
diff --git a/drivers/usb/usbip/usbip_common.c b/drivers/usb/usbip/usbip_common.c
index 2ab99244bc31..bb0596588327 100644
--- a/drivers/usb/usbip/usbip_common.c
+++ b/drivers/usb/usbip/usbip_common.c
@@ -344,6 +344,95 @@ static unsigned int tweak_transfer_flags(unsigned int flags)
return flags;
}

+/*
+ * USBIP driver packs URB transfer flags in PDUs that are exchanged
+ * between Server (usbip_host) and Client (vhci_hcd). URB_* flags
+ * are internal to kernel and could change. Where as USBIP URB flags
+ * exchanged in PDUs are USBIP user API must not change.
+ *
+ * USBIP_URB* flags are exported as explicit API and client and server
+ * do mapping from kernel flags to USBIP_URB*. Details as follows:
+ *
+ * Client tx path (USBIP_CMD_SUBMIT):
+ * - Maps URB_* to USBIP_URB_* when it sends USBIP_CMD_SUBMIT packet.
+ *
+ * Server rx path (USBIP_CMD_SUBMIT):
+ * - Maps USBIP_URB_* to URB_* when it receives USBIP_CMD_SUBMIT packet.
+ *
+ * Flags aren't included in USBIP_CMD_UNLINK and USBIP_RET_SUBMIT packets
+ * and no special handling is needed for them in the following cases:
+ * - Server rx path (USBIP_CMD_UNLINK)
+ * - Client rx path & Server tx path (USBIP_RET_SUBMIT)
+ *
+ * Code paths:
+ * usbip_pack_pdu() is the common routine that handles packing pdu from
+ * urb and unpack pdu to an urb.
+ *
+ * usbip_pack_cmd_submit() and usbip_pack_ret_submit() handle
+ * USBIP_CMD_SUBMIT and USBIP_RET_SUBMIT respectively.
+ *
+ * usbip_map_urb_to_usbip() and usbip_map_usbip_to_urb() are used
+ * by usbip_pack_cmd_submit() and usbip_pack_ret_submit() to map
+ * flags.
+ */
+
+struct urb_to_usbip_flags {
+ unsigned int urb_flag;
+ unsigned int usbip_flag;
+};
+
+#define NUM_USBIP_FLAGS 17
+
+static const struct urb_to_usbip_flags flag_map[NUM_USBIP_FLAGS] = {
+ {URB_SHORT_NOT_OK, USBIP_URB_SHORT_NOT_OK},
+ {URB_ISO_ASAP, USBIP_URB_ISO_ASAP},
+ {URB_NO_TRANSFER_DMA_MAP, USBIP_URB_NO_TRANSFER_DMA_MAP},
+ {URB_ZERO_PACKET, USBIP_URB_ZERO_PACKET},
+ {URB_NO_INTERRUPT, USBIP_URB_NO_INTERRUPT},
+ {URB_FREE_BUFFER, USBIP_URB_FREE_BUFFER},
+ {URB_DIR_IN, USBIP_URB_DIR_IN},
+ {URB_DIR_OUT, USBIP_URB_DIR_OUT},
+ {URB_DIR_MASK, USBIP_URB_DIR_MASK},
+ {URB_DMA_MAP_SINGLE, USBIP_URB_DMA_MAP_SINGLE},
+ {URB_DMA_MAP_PAGE, USBIP_URB_DMA_MAP_PAGE},
+ {URB_DMA_MAP_SG, USBIP_URB_DMA_MAP_SG},
+ {URB_MAP_LOCAL, USBIP_URB_MAP_LOCAL},
+ {URB_SETUP_MAP_SINGLE, USBIP_URB_SETUP_MAP_SINGLE},
+ {URB_SETUP_MAP_LOCAL, USBIP_URB_SETUP_MAP_LOCAL},
+ {URB_DMA_SG_COMBINED, USBIP_URB_DMA_SG_COMBINED},
+ {URB_ALIGNED_TEMP_BUFFER, USBIP_URB_ALIGNED_TEMP_BUFFER},
+};
+
+static unsigned int urb_to_usbip(unsigned int flags)
+{
+ unsigned int map_flags = 0;
+ int loop;
+
+ for (loop = 0; loop < NUM_USBIP_FLAGS; loop++) {
+ if (flags & flag_map[loop].urb_flag)
+ map_flags |= flag_map[loop].usbip_flag;
+ }
+ pr_debug("%s: flag = %u map_flags = %u\n", __func__,
+ flags, map_flags);
+
+ return map_flags;
+}
+
+static unsigned int usbip_to_urb(unsigned int flags)
+{
+ unsigned int map_flags = 0;
+ int loop;
+
+ for (loop = 0; loop < NUM_USBIP_FLAGS; loop++) {
+ if (flags & flag_map[loop].usbip_flag)
+ map_flags |= flag_map[loop].urb_flag;
+ }
+ pr_debug("%s: flag = %u map_flags = %u\n", __func__,
+ flags, map_flags);
+
+ return map_flags;
+}
+
static void usbip_pack_cmd_submit(struct usbip_header *pdu, struct urb *urb,
int pack)
{
@@ -354,14 +443,14 @@ static void usbip_pack_cmd_submit(struct usbip_header *pdu, struct urb *urb,
* will be discussed when usbip is ported to other operating systems.
*/
if (pack) {
- spdu->transfer_flags =
- tweak_transfer_flags(urb->transfer_flags);
+ /* map after tweaking the urb flags */
+ spdu->transfer_flags = urb_to_usbip(tweak_transfer_flags(urb->transfer_flags));
spdu->transfer_buffer_length = urb->transfer_buffer_length;
spdu->start_frame = urb->start_frame;
spdu->number_of_packets = urb->number_of_packets;
spdu->interval = urb->interval;
} else {
- urb->transfer_flags = spdu->transfer_flags;
+ urb->transfer_flags = usbip_to_urb(spdu->transfer_flags);
urb->transfer_buffer_length = spdu->transfer_buffer_length;
urb->start_frame = spdu->start_frame;
urb->number_of_packets = spdu->number_of_packets;
diff --git a/drivers/usb/usbip/vhci_tx.c b/drivers/usb/usbip/vhci_tx.c
index 0ae40a13a9fe..0cf3413ea32d 100644
--- a/drivers/usb/usbip/vhci_tx.c
+++ b/drivers/usb/usbip/vhci_tx.c
@@ -25,6 +25,7 @@ static void setup_cmd_submit_pdu(struct usbip_header *pdup, struct urb *urb)
USBIP_DIR_IN : USBIP_DIR_OUT;
pdup->base.ep = usb_pipeendpoint(urb->pipe);

+ /* pack the pdu from urb. Map URB_* to USBIP_URB_* flags */
usbip_pack_pdu(pdup, urb, USBIP_CMD_SUBMIT, 1);

if (urb->setup_packet)
diff --git a/drivers/usb/usbip/vudc_rx.c b/drivers/usb/usbip/vudc_rx.c
index d4a2f30a7580..b0efd6e00e6b 100644
--- a/drivers/usb/usbip/vudc_rx.c
+++ b/drivers/usb/usbip/vudc_rx.c
@@ -26,6 +26,7 @@ static int alloc_urb_from_cmd(struct urb **urbp,
if (!urb)
goto err;

+ /* unpack the pdu to a urb. Map USBIP_URB_* to URB_* flags */
usbip_pack_pdu(pdu, urb, USBIP_CMD_SUBMIT, 0);

if (urb->transfer_buffer_length > 0) {
diff --git a/include/uapi/linux/usbip.h b/include/uapi/linux/usbip.h
index fd393d908d8a..22d25ebde0cc 100644
--- a/include/uapi/linux/usbip.h
+++ b/include/uapi/linux/usbip.h
@@ -24,4 +24,44 @@ enum usbip_device_status {
VDEV_ST_USED,
VDEV_ST_ERROR
};
+
+/* USB URB Transfer flags:
+ *
+ * USBIP server and client (vchi) pack URBs in TCP packets.
+ *
+ * - Client (vhci) clears the DMA flag and sends it off to the server.
+ * - Server (usbip-host) masks some flags and re-submits client urb to
+ * usbcore.
+ * - USBIP protocol has its own direction field and doesn't use URB_DIR_IN
+ *
+ * As a result of coying the transfer flags, they now have become part
+ * of the API. Any changes to kernel flags now impact the USBIP user-space.
+ * In addition, it will be compatibility problem between server and client.
+ * These defines aren't directly referenced and it is an obscure usage
+ * hidden away in the packets.
+ *
+ * Add code to translate the values between the numbers used in userspace
+ * and the numbers used in the kernel. This will help with any future
+ * changes to kernel flags breaking the API.
+ */
+
+#define USBIP_URB_SHORT_NOT_OK 0x0001
+#define USBIP_URB_ISO_ASAP 0x0002
+#define USBIP_URB_NO_TRANSFER_DMA_MAP 0x0004
+#define USBIP_URB_ZERO_PACKET 0x0040
+#define USBIP_URB_NO_INTERRUPT 0x0080
+#define USBIP_URB_FREE_BUFFER 0x0100
+#define USBIP_URB_DIR_IN 0x0200
+#define USBIP_URB_DIR_OUT 0
+#define USBIP_URB_DIR_MASK USBIP_URB_DIR_IN
+
+#define USBIP_URB_DMA_MAP_SINGLE 0x00010000
+#define USBIP_URB_DMA_MAP_PAGE 0x00020000
+#define USBIP_URB_DMA_MAP_SG 0x00040000
+#define USBIP_URB_MAP_LOCAL 0x00080000
+#define USBIP_URB_SETUP_MAP_SINGLE 0x00100000
+#define USBIP_URB_SETUP_MAP_LOCAL 0x00200000
+#define USBIP_URB_DMA_SG_COMBINED 0x00400000
+#define USBIP_URB_ALIGNED_TEMP_BUFFER 0x00800000
+
#endif /* _UAPI_LINUX_USBIP_H */
--
2.34.1

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