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[76.102.12.149]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-129b41289e7sm3582603c88.10.2026.03.18.09.16.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2026 09:16:25 -0700 (PDT) Date: Wed, 18 Mar 2026 09:16:24 -0700 From: Stanislav Fomichev To: Stanislav Fomichev Cc: netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, corbet@lwn.net, skhan@linuxfoundation.org, andrew+netdev@lunn.ch, michael.chan@broadcom.com, pavan.chebbi@broadcom.com, anthony.l.nguyen@intel.com, przemyslaw.kitszel@intel.com, saeedm@nvidia.com, tariqt@nvidia.com, mbloch@nvidia.com, alexanderduyck@fb.com, kernel-team@meta.com, johannes@sipsolutions.net, sd@queasysnail.net, jianbol@nvidia.com, dtatulea@nvidia.com, mohsin.bashr@gmail.com, jacob.e.keller@intel.com, willemb@google.com, skhawaja@google.com, bestswngs@gmail.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, intel-wired-lan@lists.osuosl.org, linux-rdma@vger.kernel.org, linux-wireless@vger.kernel.org, linux-kselftest@vger.kernel.org, leon@kernel.org Subject: Re: [PATCH net-next v2 02/13] wifi: cfg80211: use __rtnl_unlock in nl80211_pre_doit Message-ID: Mail-Followup-To: Stanislav Fomichev , Stanislav Fomichev , netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, corbet@lwn.net, skhan@linuxfoundation.org, andrew+netdev@lunn.ch, michael.chan@broadcom.com, pavan.chebbi@broadcom.com, anthony.l.nguyen@intel.com, przemyslaw.kitszel@intel.com, saeedm@nvidia.com, tariqt@nvidia.com, mbloch@nvidia.com, alexanderduyck@fb.com, kernel-team@meta.com, johannes@sipsolutions.net, sd@queasysnail.net, jianbol@nvidia.com, dtatulea@nvidia.com, mohsin.bashr@gmail.com, jacob.e.keller@intel.com, willemb@google.com, skhawaja@google.com, bestswngs@gmail.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, intel-wired-lan@lists.osuosl.org, linux-rdma@vger.kernel.org, linux-wireless@vger.kernel.org, linux-kselftest@vger.kernel.org, leon@kernel.org References: <20260318150305.123900-1-sdf@fomichev.me> <20260318150305.123900-3-sdf@fomichev.me> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260318150305.123900-3-sdf@fomichev.me> On 03/18, Stanislav Fomichev wrote: > nl80211_pre_doit acquires rtnl_lock and then wiphy_lock, releasing > rtnl while keeping wiphy_lock held until post_doit. With the > introduction of rx_mode_wq and its flush in netdev_run_todo, calling > rtnl_unlock here creates a circular lock dependency: > > Chain exists of: > (wq_completion)rx_mode_wq --> rtnl_mutex --> &rdev->wiphy.mtx > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(&rdev->wiphy.mtx); > lock(rtnl_mutex); > lock(&rdev->wiphy.mtx); > lock((wq_completion)rx_mode_wq); > > Switch to __rtnl_unlock to skip netdev_run_todo in nl80211_pre_doit. > This seems safe because we run before the op. > > Link: http://lore.kernel.org/netdev/69b5ad67.a00a0220.3b25d1.001a.GAE@google.com > Signed-off-by: Stanislav Fomichev > --- > net/wireless/nl80211.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c > index 2225f5d0b124..ce5f25d4c87e 100644 > --- a/net/wireless/nl80211.c > +++ b/net/wireless/nl80211.c > @@ -18192,7 +18192,7 @@ static int nl80211_pre_doit(const struct genl_split_ops *ops, > __release(&rdev->wiphy.mtx); > } > if (!(internal_flags & NL80211_FLAG_NEED_RTNL)) > - rtnl_unlock(); > + __rtnl_unlock(); > > return 0; > out_unlock: > -- > 2.53.0 > ERROR: modpost: "__rtnl_unlock" [net/wireless/cfg80211.ko] undefined! Gonna re-run local nipa ingest locally to see if anything else pops up. --- pw-bot: cr