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Tue, 03 Feb 2026 00:44:33 -0800 (PST) Message-ID: <14cb0b22-ec39-43e4-a35b-22ad558b2e34@redhat.com> Date: Tue, 3 Feb 2026 09:44:31 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Intel-wired-lan] [PATCH net] iavf: fix deadlock in reset handling To: Jacob Keller , Jakub Kicinski Cc: ivecera@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Lunn , Eric Dumazet , Stanislav Fomichev , Tony Nguyen , Przemek Kitszel , intel-wired-lan@lists.osuosl.org, Paolo Abeni , "David S. Miller" References: <20260202084820.260033-1-poros@redhat.com> <20260202155813.3f8fbc27@kernel.org> Content-Language: en-US From: Petr Oros In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2/3/26 02:00, Jacob Keller wrote: > > > On 2/2/2026 3:58 PM, Jakub Kicinski wrote: >> On Mon,  2 Feb 2026 09:48:20 +0100 Petr Oros wrote: >>> +    netdev_unlock(netdev); >>> +    ret = wait_event_interruptible_timeout(adapter->reset_waitqueue, >>> + !iavf_is_reset_in_progress(adapter), >>> +                           msecs_to_jiffies(5000)); >>> +    netdev_lock(netdev); >> >> Dropping locks taken by the core around the driver callback >> is obviously unacceptable. SMH. > > Right. It seems like the correct fix is to either a) have reset take > and hold the netdev lock (now that its distinct from the global RTNL > lock) or b) refactor reset so that it can defer any of the netdev > related stuff somehow. > I modeled this after the existing pattern in iavf_close() (ndo_stop), which also temporarily releases the netdev instance lock taken by the core to wait for an async operation to complete: static int iavf_close(struct net_device *netdev) {         netdev_assert_locked(netdev);         ...         iavf_down(adapter);         iavf_change_state(adapter, __IAVF_DOWN_PENDING);         iavf_free_traffic_irqs(adapter);         netdev_unlock(netdev);         status = wait_event_timeout(adapter->down_waitqueue,                                     adapter->state == __IAVF_DOWN,                                     msecs_to_jiffies(500));         if (!status)                 netdev_warn(netdev, "Device resources not yet released\n");         netdev_lock(netdev);         ... } This was introduced by commit 120f28a6f314fe ("iavf: get rid of the crit lock"), and ndo_stop is called with netdev instance lock held by the core just like ndo_change_mtu is. Could you clarify why the unlock-wait-lock pattern is acceptable in ndo_stop but not here?