This issue was found by Runcheng Lu when develop HSCanT USB to CAN FD converter[1]. The original developers may have only 3 intefaces device to test so they write 3 here and wait for future change.
During the HSCanT development, we actually used 4 interfaces, so the limitation of 3 is not enough now. But just increase one is not future-proofed. Since the channel type in gs_host_frame is u8, just increase interface number limit to max size of u8 safely.
[1]: https://github.com/cherry-embedded/HSCanT-hardware
Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices") Reported-by: Runcheng Lu runcheng.lu@hpmicro.com Cc: stable@vger.kernel.org Signed-off-by: Celeste Liu uwu@coelacanthus.name --- Changes in v3: - Cc stable should in patch instead of cover letter. - Link to v2: https://lore.kernel.org/r/20250930-gs-usb-max-if-v2-1-2cf9a44e6861@coelacant...
Changes in v2: - Use flexible array member instead of fixed array. - Link to v1: https://lore.kernel.org/r/20250929-gs-usb-max-if-v1-1-e41b5c09133a@coelacant... --- drivers/net/can/usb/gs_usb.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c index c9482d6e947b0c7b033dc4f0c35f5b111e1bfd92..69b068c8fa8fbab42337e2b0a3d0860ac678c792 100644 --- a/drivers/net/can/usb/gs_usb.c +++ b/drivers/net/can/usb/gs_usb.c @@ -289,11 +289,6 @@ struct gs_host_frame { #define GS_MAX_RX_URBS 30 #define GS_NAPI_WEIGHT 32
-/* Maximum number of interfaces the driver supports per device. - * Current hardware only supports 3 interfaces. The future may vary. - */ -#define GS_MAX_INTF 3 - struct gs_tx_context { struct gs_can *dev; unsigned int echo_id; @@ -324,7 +319,6 @@ struct gs_can {
/* usb interface struct */ struct gs_usb { - struct gs_can *canch[GS_MAX_INTF]; struct usb_anchor rx_submitted; struct usb_device *udev;
@@ -336,9 +330,11 @@ struct gs_usb {
unsigned int hf_size_rx; u8 active_channels; + u8 channel_cnt;
unsigned int pipe_in; unsigned int pipe_out; + struct gs_can *canch[] __counted_by(channel_cnt); };
/* 'allocate' a tx context. @@ -599,7 +595,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb) }
/* device reports out of range channel id */ - if (hf->channel >= GS_MAX_INTF) + if (hf->channel >= parent->channel_cnt) goto device_detach;
dev = parent->canch[hf->channel]; @@ -699,7 +695,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb) /* USB failure take down all interfaces */ if (rc == -ENODEV) { device_detach: - for (rc = 0; rc < GS_MAX_INTF; rc++) { + for (rc = 0; rc < parent->channel_cnt; rc++) { if (parent->canch[rc]) netif_device_detach(parent->canch[rc]->netdev); } @@ -1460,17 +1456,19 @@ static int gs_usb_probe(struct usb_interface *intf, icount = dconf.icount + 1; dev_info(&intf->dev, "Configuring for %u interfaces\n", icount);
- if (icount > GS_MAX_INTF) { + if (icount > type_max(typeof(parent->channel_cnt))) { dev_err(&intf->dev, "Driver cannot handle more that %u CAN interfaces\n", - GS_MAX_INTF); + type_max(typeof(parent->channel_cnt))); return -EINVAL; }
- parent = kzalloc(sizeof(*parent), GFP_KERNEL); + parent = kzalloc(struct_size(parent, canch, icount), GFP_KERNEL); if (!parent) return -ENOMEM;
+ parent->channel_cnt = icount; + init_usb_anchor(&parent->rx_submitted);
usb_set_intfdata(intf, parent); @@ -1531,7 +1529,7 @@ static void gs_usb_disconnect(struct usb_interface *intf) return; }
- for (i = 0; i < GS_MAX_INTF; i++) + for (i = 0; i < parent->channel_cnt; i++) if (parent->canch[i]) gs_destroy_candev(parent->canch[i]);
--- base-commit: e5f0a698b34ed76002dc5cff3804a61c80233a7a change-id: 20250929-gs-usb-max-if-a304c83243e5
Best regards,
On 9/30/25 12:06 PM, Celeste Liu wrote:
This issue was found by Runcheng Lu when develop HSCanT USB to CAN FD converter[1]. The original developers may have only 3 intefaces device to
^^^^^^^^^ interfaces (missing "r")
test so they write 3 here and wait for future change.
During the HSCanT development, we actually used 4 interfaces, so the limitation of 3 is not enough now. But just increase one is not future-proofed. Since the channel type in gs_host_frame is u8, just increase interface number limit to max size of u8 safely.
Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices") Reported-by: Runcheng Lu runcheng.lu@hpmicro.com Cc: stable@vger.kernel.org Signed-off-by: Celeste Liu uwu@coelacanthus.name
Reviewed-by: Vincent Mailhol mailhol@kernel.org
The patch is good as-is. However, speaking of the interface numbers, there is another issue in this gs_usb driver: net_device->dev_port is not populated, and according to the documentation, this is a bug.
See the description here:
https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-class-net
What: /sys/class/net/<iface>/dev_port
Date: February 2014
KernelVersion: 3.15
Contact: netdev@vger.kernel.org
Description:
Indicates the port number of this network device, formatted
as a decimal value. Some NICs have multiple independent ports
on the same PCI bus, device and function. This attribute allows
userspace to distinguish the respective interfaces.
Note: some device drivers started to use 'dev_id' for this
purpose since long before 3.15 and have not adopted the new
attribute ever since. To query the port number, some tools look
exclusively at 'dev_port', while others only consult 'dev_id'.
If a network device has multiple client adapter ports as
described in the previous paragraph and does not set this
attribute to its port number, it's a kernel bug.
Would you mind sending a separate patch (with a Fixes: tag) to resolve this?
Yours sincerely, Vincent Mailhol
On 2025-09-30 13:44, Vincent Mailhol wrote:
On 9/30/25 12:06 PM, Celeste Liu wrote:
This issue was found by Runcheng Lu when develop HSCanT USB to CAN FD converter[1]. The original developers may have only 3 intefaces device to
^^^^^^^^^interfaces (missing "r")
Fixed in v4. Redundant typeof() was removed as well.
test so they write 3 here and wait for future change.
During the HSCanT development, we actually used 4 interfaces, so the limitation of 3 is not enough now. But just increase one is not future-proofed. Since the channel type in gs_host_frame is u8, just increase interface number limit to max size of u8 safely.
Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices") Reported-by: Runcheng Lu runcheng.lu@hpmicro.com Cc: stable@vger.kernel.org Signed-off-by: Celeste Liu uwu@coelacanthus.name
Reviewed-by: Vincent Mailhol mailhol@kernel.org
The patch is good as-is. However, speaking of the interface numbers, there is another issue in this gs_usb driver: net_device->dev_port is not populated, and according to the documentation, this is a bug.
See the description here:
https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-class-net
What: /sys/class/net/<iface>/dev_port
Date: February 2014
KernelVersion: 3.15
Contact: netdev@vger.kernel.org
Description:
Indicates the port number of this network device, formatted as a decimal value. Some NICs have multiple independent ports on the same PCI bus, device and function. This attribute allows userspace to distinguish the respective interfaces. Note: some device drivers started to use 'dev_id' for this purpose since long before 3.15 and have not adopted the new attribute ever since. To query the port number, some tools look exclusively at 'dev_port', while others only consult 'dev_id'. If a network device has multiple client adapter ports as described in the previous paragraph and does not set this attribute to its port number, it's a kernel bug.Would you mind sending a separate patch (with a Fixes: tag) to resolve this?
Ok. I will send a patch for it later.
Yours sincerely, Vincent Mailhol
Hi Celeste,
Sorry, one last minute comment which I forgot in my previous message.
On 9/30/25 12:06 PM, Celeste Liu wrote:
This issue was found by Runcheng Lu when develop HSCanT USB to CAN FD converter[1]. The original developers may have only 3 intefaces device to test so they write 3 here and wait for future change.
During the HSCanT development, we actually used 4 interfaces, so the limitation of 3 is not enough now. But just increase one is not future-proofed. Since the channel type in gs_host_frame is u8, just increase interface number limit to max size of u8 safely.
Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices") Reported-by: Runcheng Lu runcheng.lu@hpmicro.com Cc: stable@vger.kernel.org Signed-off-by: Celeste Liu uwu@coelacanthus.name
Changes in v3:
- Cc stable should in patch instead of cover letter.
- Link to v2: https://lore.kernel.org/r/20250930-gs-usb-max-if-v2-1-2cf9a44e6861@coelacant...
Changes in v2:
- Use flexible array member instead of fixed array.
- Link to v1: https://lore.kernel.org/r/20250929-gs-usb-max-if-v1-1-e41b5c09133a@coelacant...
drivers/net/can/usb/gs_usb.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c index c9482d6e947b0c7b033dc4f0c35f5b111e1bfd92..69b068c8fa8fbab42337e2b0a3d0860ac678c792 100644 --- a/drivers/net/can/usb/gs_usb.c +++ b/drivers/net/can/usb/gs_usb.c @@ -289,11 +289,6 @@ struct gs_host_frame { #define GS_MAX_RX_URBS 30 #define GS_NAPI_WEIGHT 32 -/* Maximum number of interfaces the driver supports per device.
- Current hardware only supports 3 interfaces. The future may vary.
- */
-#define GS_MAX_INTF 3
struct gs_tx_context { struct gs_can *dev; unsigned int echo_id; @@ -324,7 +319,6 @@ struct gs_can { /* usb interface struct */ struct gs_usb {
- struct gs_can *canch[GS_MAX_INTF]; struct usb_anchor rx_submitted; struct usb_device *udev;
@@ -336,9 +330,11 @@ struct gs_usb { unsigned int hf_size_rx; u8 active_channels;
- u8 channel_cnt;
unsigned int pipe_in; unsigned int pipe_out;
- struct gs_can *canch[] __counted_by(channel_cnt);
}; /* 'allocate' a tx context. @@ -599,7 +595,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb) } /* device reports out of range channel id */
- if (hf->channel >= GS_MAX_INTF)
- if (hf->channel >= parent->channel_cnt) goto device_detach;
dev = parent->canch[hf->channel]; @@ -699,7 +695,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb) /* USB failure take down all interfaces */ if (rc == -ENODEV) { device_detach:
for (rc = 0; rc < GS_MAX_INTF; rc++) {
for (rc = 0; rc < parent->channel_cnt; rc++) { if (parent->canch[rc]) netif_device_detach(parent->canch[rc]->netdev);@@ -1460,17 +1456,19 @@ static int gs_usb_probe(struct usb_interface *intf, icount = dconf.icount + 1; dev_info(&intf->dev, "Configuring for %u interfaces\n", icount);
- if (icount > GS_MAX_INTF) {
- if (icount > type_max(typeof(parent->channel_cnt))) {
^^^^^^ If you send a v4 to fix the typo, can you also remove this typeof()?
It used to be required, but this is not the case anymore since commit bd1ebf2467f9 ("overflow: Allow non-type arg to type_max() and type_min()").
(my Reviewed-by tag is still valid).
dev_err(&intf->dev, "Driver cannot handle more that %u CAN interfaces\n",
GS_MAX_INTF);
type_max(typeof(parent->channel_cnt)));
^^^^^^ same
return -EINVAL;}
- parent = kzalloc(sizeof(*parent), GFP_KERNEL);
- parent = kzalloc(struct_size(parent, canch, icount), GFP_KERNEL); if (!parent) return -ENOMEM;
- parent->channel_cnt = icount;
- init_usb_anchor(&parent->rx_submitted);
usb_set_intfdata(intf, parent); @@ -1531,7 +1529,7 @@ static void gs_usb_disconnect(struct usb_interface *intf) return; }
- for (i = 0; i < GS_MAX_INTF; i++)
- for (i = 0; i < parent->channel_cnt; i++) if (parent->canch[i]) gs_destroy_candev(parent->canch[i]);
linux-stable-mirror@lists.linaro.org
-
Celeste Liu -
Vincent Mailhol