Re: rtlwifi, rtl8192se bug soft-lockup

[Larry Finger <Larry.Finger@lwfinger.net>]

On 12/07/2011 07:59 AM, Philipp Dreimann wrote:
> On 29 November 2011 00:16, Larry Finger<Larry.Finger@lwfinger.net>  wrote:
>> On 11/28/2011 06:58 PM, Philipp Dreimann wrote:
>>  From a quick look, Stanislaw's patch should fix your system. If not, then
>> please consider pulling a git tree and checking out commit 34ddb20, which is
>> the one before 67fc6052.
>
> It fixed the issue *but* I am currently back to kernel v3.0.3, as it
> is the most stable for me. I am not sure whether new issues were
> introduced by using a v3.2-rc or if there is more wrong in the
> rtl8192se driver itself. I had random sound and standby issues at
> which I will have a look some other day.

The bug that affected 3.2-rcX and fixed by Stanislaw's patch was not introduced 
until 3.1. A patch to fix it there was just queued by GregKH.

> Another idea about the problem:
> I omitted for some reason the following line in the first email about
> the problem:
> [  732.056049] BUG: soft lockup - CPU#0 stuck for 22s! [kworker/0:3:2112]

That was a serious omission.

> While looking at the Call Trace and the code I have no idea why
> rtl92s_phy_set_rf_power_state needs that much time for the ERFSLEEP
> operation. I suspected an issue in the loop but did not find it so
> far.

With a modern CPU, no loop can take 22s unless it involves a spin lock that 
never is released.

> Another solution which I tested was the following:
> 0. rtl_lps_leave function informs the  rtl92s_phy_set_rf_power_state
> being in the ERFSLEEP-case-loop, that it needs the lock.
> 1. rtl92s_phy_set_rf_power_state notices, "return false" ( leaves the
> loop and function as if the action failed ) and the lock is released.
>
> This seemed to work fine as well. - But I am not sure what this might
> break for others...

Is this the same patch that you posted on the linux-wireless ML? Although I have 
not heard back from Chaoming, I formatted that patch correctly and submitted it 
to John Linville yesterday with the notation that it should be applied to the 
stable kernels.

Larry