Bug 207539 - Log flooding with ath9k_htc driver "Short RX data len, dropping"
Summary: Log flooding with ath9k_htc driver "Short RX data len, dropping"
Status: NEW
Alias: None
Product: Drivers
Classification: Unclassified
Component: Network (show other bugs)
Hardware: All Linux
: P1 low
Assignee: drivers_network@kernel-bugs.osdl.org
Depends on:
Reported: 2020-05-01 19:43 UTC by Den
Modified: 2020-06-08 20:59 UTC (History)
1 user (show)

See Also:
Kernel Version: 4.19.97-v7+ armv7l, 5.3.0-46-generic x86_64
Tree: Mainline
Regression: No


Description Den 2020-05-01 19:43:46 UTC
I have a USB Wifi adapter TP-Link TL-WN722N.
I use it on a x86_64 machine and on a Raspberry Pi 2.

But the ath9k_htc driver, in my physical environment, flooding the logs (5-15 times/s), with this kind of message, on all computer I use it on:

kernel: ath: phy0: Short RX data len, dropping (dlen: 4)

It is working correclty with driver ath9k_htc (client, AP, client+AP).

kernel: usb 1-1.4: new high-speed USB device number 4 using dwc_otg
kernel: usb 1-1.4: New USB device found, idVendor=0cf3, idProduct=9271, bcdDevice= 1.08
kernel: usb 1-1.4: New USB device strings: Mfr=16, Product=32, SerialNumber=48
kernel: usb 1-1.4: Product: USB2.0 WLAN
kernel: usb 1-1.4: Manufacturer: ATHEROS
kernel: usb 1-1.4: SerialNumber: 12345
kernel: usb 1-1.4: ath9k_htc: Firmware ath9k_htc/htc_9271-1.4.0.fw requested
kernel: usbcore: registered new interface driver ath9k_htc
kernel: usb 1-1.4: ath9k_htc: Transferred FW: ath9k_htc/htc_9271-1.4.0.fw, size: 51008
kernel: ath9k_htc 1-1.4:1.0: ath9k_htc: HTC initialized with 33 credits
kernel: ath9k_htc 1-1.4:1.0: ath9k_htc: FW Version: 1.4
kernel: ath9k_htc 1-1.4:1.0: FW RMW support: On
kernel: ath: EEPROM regdomain: 0x809c
kernel: ath: EEPROM indicates we should expect a country code
kernel: ath: doing EEPROM country->regdmn map search
kernel: ath: country maps to regdmn code: 0x52
kernel: ath: Country alpha2 being used: CN
kernel: ath: Regpair used: 0x52
kernel: ieee80211 phy0: Atheros AR9271 Rev:1

This log was introduced in this kernel patch:

+	if (unlikely(!rs_datalen || (rs_datalen < 10 && !is_phyerr))) {
+		ath_warn(common,
+			 "Short RX data len, dropping (dlen: %d)\n",
+			 rs_datalen);
 		goto rx_next;

- So, is it really mandatory to log this kind of thing (the Wifi adapter is working correctly as far as I now, with good speed 50+Mbps) ?
- Or can it be activated in some debug mode?
- or this ath_warn() completely removed?

For now, the solution I have for now (appart from modifying myself/recompiling the driver) is use a syslog filter to discard those lines and journald in memory only, otherwise it just fills the logs partition up.

Best regards,
Comment 1 Masashi Honma 2020-05-02 02:16:01 UTC
Thank you for reporting.

This warning indicates that the device received an improperly sized frame.
This warning is useful to recognize that your device (Wi-Fi dongle or USB hub etc) is noisy.
Though now I understand by googling some devices output so many the warning like your device.

So I will send a patch to make this warning debug message.

Note You need to log in before you can comment on or make changes to this bug.