Re: [PATCH] brcm80211: fmac: Add error check for brcmf_usb_dlneeded()

[Arend Van Spriel <arend.vanspriel@broadcom.com>]

On April 9, 2025 2:11:08 PM Arend van Spriel <arend.vanspriel@broadcom.com> 
wrote:

> On 4/6/2025 10:19 AM, Wentao Liang wrote:
>> The function brcmf_usb_dlneeded() calls the function brcmf_usb_dl_cmd()
>> but dose not check its return value. The 'id.chiprev' is uninitialized if
>> the function brcmf_usb_dl_cmd() fails, and may propagate to
>> 'devinfo->bus_pub.chiprev'.
>>
>> Add error handling for brcmf_usb_dl_cmd() to return the function if the
>> 'id.chiprev' is uninitialized.
>
> Thanks for the patch, but NAK. Let me explain why below...
>
>> Fixes: 71bb244ba2fd ("brcm80211: fmac: add USB support for bcm43235/6/8 
>> chipsets")
>> Cc: stable@vger.kernel.org # v3.4+
>> Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
>> ---
>> drivers/net/wireless/broadcom/brcm80211/brcmfmac/usb.c | 7 ++++++-
>> 1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/usb.c 
>> b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/usb.c
>> index 2821c27f317e..50dddac8a2ab 100644
>> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/usb.c
>> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/usb.c
>> @@ -790,6 +790,7 @@ brcmf_usb_dlneeded(struct brcmf_usbdev_info *devinfo)
>> {
>> struct bootrom_id_le id;
>> u32 chipid, chiprev;
>> + int err;
>>
>> brcmf_dbg(USB, "Enter\n");
>>
>> @@ -798,7 +799,11 @@ brcmf_usb_dlneeded(struct brcmf_usbdev_info *devinfo)
>>
>> /* Check if firmware downloaded already by querying runtime ID */
>> id.chip = cpu_to_le32(0xDEAD);
>> - brcmf_usb_dl_cmd(devinfo, DL_GETVER, &id, sizeof(id));
>> + err = brcmf_usb_dl_cmd(devinfo, DL_GETVER, &id, sizeof(id));
>> + if (err) {
>> + brcmf_err("DL_GETID Failed\n");
>> + return false;
>
> The boolean return value does not indicate pass or fail. It answers the
> question implied by the function name brcmf_usb_dlneeded(), ie. is the
> USB device running firmware (false) or do we need to download firmware
> (true). So returning false here is not going to help us.
>
> The id.chip is initialized to 0xDEAD so upon a failure that value is
> being passed to brcmf_usb_prepare_fw_request() which will consequently
> return NULL, because we do not support a 0xDEAD chip. So there is no
> need to bail out here. Just print the failure message is enough although
> I would suggest to include the err value:
>
> - brcmf_usb_dl_cmd(devinfo, DL_GETVER, &id, sizeof(id));
> + err = brcmf_usb_dl_cmd(devinfo, DL_GETVER, &id, sizeof(id));
> + if (err)
> + brcmf_err("DL_GETVER failed: err=%d\n", err);

Maybe an error message in brcmf_usb_dl_cmd() would suffice printing the 
command id and error value. That way every invocation of the function logs 
a message upon failure.

Regards,
Arend
>