Messages in this thread | | | Subject | Re: [PATCH] net: wireless: iwlegacy: Fix possible data races in il4965_send_rxon_assoc() | From | Jia-Ju Bai <> | Date | Fri, 5 Oct 2018 21:42:55 +0800 |
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On 2018/10/5 15:54, Stanislaw Gruszka wrote: > On Thu, Oct 04, 2018 at 04:52:19PM +0800, Jia-Ju Bai wrote: >> On 2018/10/4 15:59, Stanislaw Gruszka wrote: >>> On Wed, Oct 03, 2018 at 10:07:45PM +0800, Jia-Ju Bai wrote: >>>> These possible races are detected by a runtime testing. >>>> To fix these races, the mutex lock is used in il4965_send_rxon_assoc() >>>> to protect the data. >>> Really ? I'm surprised by that, see below. >> My runtime testing shows that il4965_send_rxon_assoc() and >> il4965_configure_filter() are concurrently executed. >> But after seeing your reply, I need to carefully check whether my >> runtime testing is right, because I think you are right. >> In fact, I only monitored the iwl4965 driver, but did not monitor >> the iwlegacy driver, so I will do the testing again with monitoring >> the lwlegacy driver. > <snip> >>> So I wonder how this patch did not cause the deadlock ? >> Oh, sorry, anyway, my patch will cause double locks... > So how those runtime test were performend such you didn't > notice this ?
I write a tool to perform runtime testing. This tool records the lock status during driver execution. Some calls to mutex_lock() are in common.c that I did not handle, so the corresponding lock status was not recorded by my tool, causing this false positive.
Now I have handled common.c, and this false positive is not reported any more. Actually, I get several new reports. I will send you these reports to you later, and hope you can have a look, thanks in advance :)
> >>> Anyway what can be done is adding: >>> >>> lockdep_assert_held(&il->mutex); >>> >>> il4965_commit_rxon() to check if we hold the mutex. >> I agree. > Care to post a patch ?
Sure :)
Best wishes, Jia-Ju Bai
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