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[220.133.187.190]) by smtp.gmail.com with ESMTPSA id mm18sm1341970pjb.39.2020.03.26.03.41.29 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 26 Mar 2020 03:41:30 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 13.0 \(3608.60.0.2.5\)) Subject: Re: [PATCH] igb: Use a sperate mutex insead of rtnl_lock() From: Kai-Heng Feng In-Reply-To: <20200326103926.20888-1-kai.heng.feng@canonical.com> Date: Thu, 26 Mar 2020 18:41:28 +0800 Cc: "Brown, Aaron F" , "David S. Miller" , "moderated list:INTEL ETHERNET DRIVERS" , "open list:NETWORKING DRIVERS" , open list Content-Transfer-Encoding: 8BIT Message-Id: References: <20200326103926.20888-1-kai.heng.feng@canonical.com> To: "Kirsher, Jeffrey T" X-Mailer: Apple Mail (2.3608.60.0.2.5) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi, > On Mar 26, 2020, at 18:39, Kai-Heng Feng wrote: > > Commit 9474933caf21 ("igb: close/suspend race in netif_device_detach") > fixed race condition between close and power management ops by using > rtnl_lock(). > > This fix is a preparation for next patch, to prevent a dead lock under > rtnl_lock() when calling runtime resume routine. > > However, we can't use device_lock() in igb_close() because when module > is getting removed, the lock is already held for igb_remove(), and > igb_close() gets called during unregistering the netdev, hence causing a > deadlock. So let's introduce a new mutex so we don't cause a deadlock > with driver core or netdev core. > > Signed-off-by: Kai-Heng Feng Please drop "igb: Use device_lock() insead of rtnl_lock()" and use this one instead. Thanks! Kai-Heng > --- > drivers/net/ethernet/intel/igb/igb_main.c | 19 +++++++++++++------ > 1 file changed, 13 insertions(+), 6 deletions(-) > > diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c > index b46bff8fe056..dc7ed5dd216b 100644 > --- a/drivers/net/ethernet/intel/igb/igb_main.c > +++ b/drivers/net/ethernet/intel/igb/igb_main.c > @@ -288,6 +288,8 @@ static const struct igb_reg_info igb_reg_info_tbl[] = { > {} > }; > > +static DEFINE_MUTEX(igb_mutex); > + > /* igb_regdump - register printout routine */ > static void igb_regdump(struct e1000_hw *hw, struct igb_reg_info *reginfo) > { > @@ -4026,9 +4028,14 @@ static int __igb_close(struct net_device *netdev, bool suspending) > > int igb_close(struct net_device *netdev) > { > + int err = 0; > + > + mutex_lock(&igb_mutex); > if (netif_device_present(netdev) || netdev->dismantle) > - return __igb_close(netdev, false); > - return 0; > + err = __igb_close(netdev, false); > + mutex_unlock(&igb_mutex); > + > + return err; > } > > /** > @@ -8760,7 +8767,7 @@ static int __igb_shutdown(struct pci_dev *pdev, bool *enable_wake, > u32 wufc = runtime ? E1000_WUFC_LNKC : adapter->wol; > bool wake; > > - rtnl_lock(); > + mutex_lock(&igb_mutex); > netif_device_detach(netdev); > > if (netif_running(netdev)) > @@ -8769,7 +8776,7 @@ static int __igb_shutdown(struct pci_dev *pdev, bool *enable_wake, > igb_ptp_suspend(adapter); > > igb_clear_interrupt_scheme(adapter); > - rtnl_unlock(); > + mutex_unlock(&igb_mutex); > > status = rd32(E1000_STATUS); > if (status & E1000_STATUS_LU) > @@ -8897,13 +8904,13 @@ static int __maybe_unused igb_resume(struct device *dev) > > wr32(E1000_WUS, ~0); > > - rtnl_lock(); > + mutex_lock(&igb_mutex); > if (!err && netif_running(netdev)) > err = __igb_open(netdev, true); > > if (!err) > netif_device_attach(netdev); > - rtnl_unlock(); > + mutex_unlock(&igb_mutex); > > return err; > } > -- > 2.17.1 >