Messages in this thread | | | Subject | Re: [PATCH] net: wireless: iwlegacy: Fix possible data races in il4965_send_rxon_assoc() | From | Jia-Ju Bai <> | Date | Thu, 4 Oct 2018 16:52:19 +0800 |
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Thanks for your reply :)
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.
> >> @@ -1297,6 +1297,7 @@ il4965_send_rxon_assoc(struct il_priv *il) >> const struct il_rxon_cmd *rxon1 = &il->staging; >> const struct il_rxon_cmd *rxon2 = &il->active; >> >> + mutex_lock(&il->mutex); >> if (rxon1->flags == rxon2->flags && > For 4965 driver il4965_send_rxon_assoc() is only called by > il_mac_bss_info_changed() and il4965_commit_rxon(). > > il_mac_bss_info_changed() acquire il->mutex and > callers of il4965_commit_rxon() acquire il->mutex > (but I did not check all of them). > > So I wonder how this patch did not cause the deadlock ?
Oh, sorry, anyway, my patch will cause double locks...
> > Anyway what can be done is adding: > > lockdep_assert_held(&il->mutex); > > il4965_commit_rxon() to check if we hold the mutex.
I agree.
Best wishes, Jia-Ju Bai
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