Wen Gong <wgong@xxxxxxxxxxxxxx> writes: > On 2020-09-08 00:22, Kalle Valo wrote: > >> Just like with the recent firmware restart patch, isn't >> ar->napi_enabled >> racy? Wouldn't test_and_set_bit() and test_and_clear_bit() be safer? >> >> Or are we holding a lock? But then that should be documented with >> lockdep_assert_held(). > > yes, ath10k_hif_start is only called from ath10k_core_start, it has > "lockdep_assert_held(&ar->conf_mutex)", and ath10k_hif_stop is only > called from ath10k_core_stop, it also has > "lockdep_assert_held(&ar->conf_mutex)". then it will not 2 thread both > enter ath10k_hif_start/ath10k_hif_stop meanwhile. Ok, but every function depending on a lock being held should still call lockdep_assert_held(), that way we can catch the bug if locking changes later. So it's not enough that ath10k_core_stop() has lockdep_assert_held(), also these napi functions should have it. I actually decided to switch using ATH10K_FLAG_NAPI_ENABLED with set_bit() & co, simpler locking that way and no lockdep_assert_held() needed anymore. Please check my changes in the pending branch, I have only compile tested them: https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&id=e0a466d296bd862080f7796b41349f9f586272c9 -- https://patchwork.kernel.org/project/linux-wireless/list/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
