Re: [PATCH net] ch9200: return error on failed register writes in ch9200_bind()
From: Paolo Abeni
Date: Thu Sep 17 2026 - 08:32:16 EST
On 9/16/26 18:58, Sergey Shtylyov wrote:
On 9/16/26 2:20 AM, netdev-bot+sashiko@xxxxxxxxxx wrote:IMHO the patches are so strictly interconnected that should land into the same (net-next) series. No fixes tags in net-next patches.
Thank you for your contribution! Sashiko AI review found 1 potential
issue(s) to consider:
Critical: 0 · High: 1 · Medium: 0 · Low: 0
- [High] Ineffective fix: the six newly added `if (retval < 0) return
retval;` checks in ch9200_bind() (drivers/net/usb/ch9200.c) cannot…
--
ch9200: return error on failed register writes in ch9200_bind()
The patch adds error checks after the six control_write() calls in
ch9200_bind() so that a failed vendor register write aborts the bind
instead of being ignored. It carries a Fixes tag for the original driver
commit 4a476bd6d1d9.
diff --git a/drivers/net/usb/ch9200.c b/drivers/net/usb/ch9200.c
index a206ffa76f1b9..ab3cd3902ed72 100644
--- a/drivers/net/usb/ch9200.c
+++ b/drivers/net/usb/ch9200.c
@@ -360,32 +360,44 @@ static int ch9200_bind(struct usbnet *dev, struct usb_interface *intf)
data[1] = 0x0F;
retval = control_write(dev, REQUEST_WRITE, 0, MAC_REG_THRESHOLD, data,
0x02, CONTROL_TIMEOUT_MS);
+ if (retval < 0)
+ return retval;
[Severity: High]
But why? 8-)
Can these new checks ever observe a failed register write? control_write()
in the same file discards the USB transfer status on its normal path:
By "failed register write" I meant any error in control_write(), including
kmemdup() failure (which precludes the USB request from being sent at all)...
drivers/net/usb/ch9200.c:control_write() {
...
err = usb_control_msg(dev->udev,
usb_sndctrlpipe(dev->udev, 0),
request, request_type, value, index, buf, size,
timeout);
if (err >= 0 && err < size)
err = -EINVAL;
kfree(buf);
return 0;
err_out:
return err;
}
The only return err; is at err_out:, which is reached solely from the
kmemdup() -ENOMEM branch. All six patched call sites pass a non-NULL
2-byte data buffer, so the only negative value the new checks can see is
-ENOMEM from that allocation.
I kinda noticed. :-)
[...]
The sibling helper control_read() already returns err on its normal path,
and ch9200_mdio_read() checks it with if (ret < 0), so the convention
control_write() is expected to follow already exists in this file.
And I'm extending it to control_write(), but in another patch...
Would it make more sense to change control_write() to return err after
kfree(buf) instead of (or in addition to) adding the caller-side checks?
As it stands the commit message claim that this makes the driver "bail out
of ch9200_bind() on failed writes" does not seem to hold for actual
transfer failures.
I'm getting bored...
If any *human* maintainer insists that I merge the 2 patches, I surely
will... Or maybe I should resubmit both against net.git (net-next.git?) as
a series?
Thanks,
Paolo