Re: rtl8192cu: slow path warning

From: Larry Finger
Date: Wed Jun 26 2013 - 11:54:15 EST

On 06/26/2013 09:22 AM, Richard GENOUD wrote:
Using 3.10-rc7, I'm still seeing the warning, BUT ONLY on the first
connection.

[ 40.312500] usb 2-2: default language 0x0409
[ 40.312500] usb 2-2: udev 2, busnum 2, minor = 129
[ 40.320312] usb 2-2: New USB device found, idVendor=0bda, idProduct=8176
[ 40.328125] usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 40.328125] usb 2-2: Product: 802.11n WLAN Adapter
[ 40.335937] usb 2-2: Manufacturer: Realtek
[ 40.343750] usb 2-2: SerialNumber: 00e04c000001
[ 40.343750] usb 2-2: usb_probe_device
[ 40.351562] usb 2-2: configuration #1 chosen from 1 choice
[ 40.351562] usb 2-2: adding 2-2:1.0 (config #1, interface 0)
[ 40.500000] cfg80211: Calling CRDA to update world regulatory domain
[ 40.648437] rtl8192cu 2-2:1.0: usb_probe_interface
[ 40.656250] rtl8192cu 2-2:1.0: usb_probe_interface - got id
[ 40.664062] rtl8192cu: Chip version 0x10
[ 40.757812] rtl8192cu: MAC address: a0:f3:c1:1e:02:a0
[ 40.765625] rtl8192cu: Board Type 0
[ 40.773437] rtlwifi: rx_max_size 15360, rx_urb_num 8, in_ep 1
[ 40.773437] rtl8192cu: Loading firmware rtlwifi/rtl8192cufw.bin
[ 40.781250] usbcore: registered new interface driver rtl8192cu
[ 40.835937] ieee80211 phy0: Selected rate control algorithm 'rtl_rc'
[ 40.843750] rtlwifi: wireless switch is on
# ip link set wlan0 up
[ 59.921875] rtl8192cu: MAC auto ON okay!
[ 59.960937] rtl8192cu: Tx queue select: 0x05
# iw wlan0 connect test
[ 75.390625] wlan0: authenticate with f8:1a:67:1a:df:88
[ 75.421875] wlan0: send auth to f8:1a:67:1a:df:88 (try 1/3)
[ 75.437500] wlan0: authenticated
[ 75.453125] wlan0: associate with f8:1a:67:1a:df:88 (try 1/3)
[ 75.460937] wlan0: RX AssocResp from f8:1a:67:1a:df:88 (capab=0x401 status=0 aid=2)
[ 75.468750] wlan0: associated
[ 76.375000] ------------[ cut here ]------------
[ 76.375000] WARNING: at kernel/workqueue.c:1365 __queue_work+0x168/0x200()
[ 76.375000] Modules linked in: rtl8192cu rtl8192c_common rtlwifi mac80211 cfg80211 rfkill ehci_atmel ehci_hcd atmel_usba_udc udc_core ohci_hcd
[ 76.375000] CPU: 0 PID: 308 Comm: kworker/0:1 Not tainted 3.10.0-rc7 #36
[ 76.375000] Workqueue: rtl92c_usb rtl_watchdog_wq_callback [rtlwifi]
[ 76.375000] [<c000d9bc>] (unwind_backtrace+0x0/0xf0) from [<c000b9ec>] (show_stack+0x10/0x14)
[ 76.375000] [<c000b9ec>] (show_stack+0x10/0x14) from [<c0015c00>] (warn_slowpath_common+0x4c/0x68)
[ 76.375000] [<c0015c00>] (warn_slowpath_common+0x4c/0x68) from [<c0015c38>] (warn_slowpath_null+0x1c/0x24)
[ 76.375000] [<c0015c38>] (warn_slowpath_null+0x1c/0x24) from [<c0029e40>] (__queue_work+0x168/0x200)
[ 76.375000] [<c0029e40>] (__queue_work+0x168/0x200) from [<c0029f2c>] (queue_work_on+0x44/0x50)
[ 76.375000] [<c0029f2c>] (queue_work_on+0x44/0x50) from [<bf09bb54>] (rtl_watchdog_wq_callback+0x320/0x404 [rtlwifi])
[ 76.375000] [<bf09bb54>] (rtl_watchdog_wq_callback+0x320/0x404 [rtlwifi]) from [<c002b168>] (process_one_work+0x10c/0x354)
[ 76.375000] [<c002b168>] (process_one_work+0x10c/0x354) from [<c002b784>] (worker_thread+0x130/0x380)
[ 76.375000] [<c002b784>] (worker_thread+0x130/0x380) from [<c0030330>] (kthread+0xa4/0xb0)
[ 76.375000] [<c0030330>] (kthread+0xa4/0xb0) from [<c00092f0>] (ret_from_fork+0x14/0x24)
[ 76.375000] ---[ end trace e116b4b3d671f3d2 ]---

The WARNING is the result of a workqueue not being initialized for the USB driver.

Please try the attached patch. As you have posted on a public mailing list, May I assume that it will be OK to use your address in Reported-by/Tested-by lines in the patch submission?

Thanks,

Larry

Index: wireless-testing-save/drivers/net/wireless/rtlwifi/pci.c
===================================================================
--- wireless-testing-save.orig/drivers/net/wireless/rtlwifi/pci.c
+++ wireless-testing-save/drivers/net/wireless/rtlwifi/pci.c
@@ -1008,7 +1008,7 @@ static void _rtl_pci_prepare_bcn_tasklet
return;
}

-static void rtl_lps_change_work_callback(struct work_struct *work)
+void rtl_lps_change_work_callback(struct work_struct *work)
{
struct rtl_works *rtlworks =
container_of(work, struct rtl_works, lps_change_work);
Index: wireless-testing-save/drivers/net/wireless/rtlwifi/ps.h
===================================================================
--- wireless-testing-save.orig/drivers/net/wireless/rtlwifi/ps.h
+++ wireless-testing-save/drivers/net/wireless/rtlwifi/ps.h
@@ -49,5 +49,6 @@ void rtl_swlps_rf_awake(struct ieee80211
void rtl_swlps_rf_sleep(struct ieee80211_hw *hw);
void rtl_p2p_ps_cmd(struct ieee80211_hw *hw, u8 p2p_ps_state);
void rtl_p2p_info(struct ieee80211_hw *hw, void *data, unsigned int len);
+void rtl_lps_change_work_callback(struct work_struct *work);

#endif
Index: wireless-testing-save/drivers/net/wireless/rtlwifi/usb.c
===================================================================
--- wireless-testing-save.orig/drivers/net/wireless/rtlwifi/usb.c
+++ wireless-testing-save/drivers/net/wireless/rtlwifi/usb.c
@@ -1070,6 +1070,8 @@ int rtl_usb_probe(struct usb_interface *
spin_lock_init(&rtlpriv->locks.usb_lock);
INIT_WORK(&rtlpriv->works.fill_h2c_cmd,
rtl_fill_h2c_cmd_work_callback);
+ INIT_WORK(&rtlpriv->works.lps_change_work,
+ rtl_lps_change_work_callback);

rtlpriv->usb_data_index = 0;
init_completion(&rtlpriv->firmware_loading_complete);