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Message-ID: <20220829182929.2822fafc@p1.luc.cera.cz> Date: Mon, 29 Aug 2022 18:29:29 +0200 From: Ivan Vecera <ivecera@...hat.com> To: "Laba, SlawomirX" <slawomirx.laba@...el.com> Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "Keller, Jacob E" <jacob.e.keller@...el.com>, "Piotrowski, Patryk" <patryk.piotrowski@...el.com>, Vitaly Grinberg <vgrinber@...hat.com>, "Brandeburg, Jesse" <jesse.brandeburg@...el.com>, "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>, "David S. Miller" <davem@...emloft.net>, "Eric Dumazet" <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Jeff Kirsher <jeffrey.t.kirsher@...el.com>, "moderated list:INTEL ETHERNET DRIVERS" <intel-wired-lan@...ts.osuosl.org>, open list <linux-kernel@...r.kernel.org> Subject: Re: [PATCH net] iavf: Detach device during reset task On Mon, 22 Aug 2022 17:42:44 +0000 "Laba, SlawomirX" <slawomirx.laba@...el.com> wrote: > > -----Original Message----- > > From: ivecera <ivecera@...hat.com> > > Sent: Thursday, August 18, 2022 6:56 PM > > To: netdev@...r.kernel.org > > Cc: Keller, Jacob E <jacob.e.keller@...el.com>; Piotrowski, Patryk > > <patryk.piotrowski@...el.com>; Vitaly Grinberg <vgrinber@...hat.com>; > > Brandeburg, Jesse <jesse.brandeburg@...el.com>; Nguyen, Anthony L > > <anthony.l.nguyen@...el.com>; David S. Miller <davem@...emloft.net>; Eric > > Dumazet <edumazet@...gle.com>; Jakub Kicinski <kuba@...nel.org>; Paolo > > Abeni <pabeni@...hat.com>; Jeff Kirsher <jeffrey.t.kirsher@...el.com>; > > moderated list:INTEL ETHERNET DRIVERS <intel-wired-lan@...ts.osuosl.org>; > > open list <linux-kernel@...r.kernel.org> > > Subject: [PATCH net] iavf: Detach device during reset task > > > > iavf_reset_task() takes crit_lock at the beginning and holds it during whole call. > > The function subsequently calls > > iavf_init_interrupt_scheme() that grabs RTNL. Problem occurs when userspace > > initiates during the reset task any ndo callback that runs under RTNL like > > iavf_open() because some of that functions tries to take crit_lock. This leads to > > classic A-B B-A deadlock scenario. > > > > To resolve this situation the device should be detached in > > iavf_reset_task() prior taking crit_lock to avoid subsequent ndos running under > > RTNL and reattach the device at the end. > > > > Fixes: 62fe2a865e6d ("i40evf: add missing rtnl_lock() around > > i40evf_set_interrupt_capability") > > Cc: Jacob Keller <jacob.e.keller@...el.com> > > Cc: Patryk Piotrowski <patryk.piotrowski@...el.com> > > Tested-by: Vitaly Grinberg <vgrinber@...hat.com> > > Signed-off-by: Ivan Vecera <ivecera@...hat.com> > > --- > > drivers/net/ethernet/intel/iavf/iavf_main.c | 22 +++++++++++++++------ > > 1 file changed, 16 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c > > b/drivers/net/ethernet/intel/iavf/iavf_main.c > > index f39440ad5c50..ee8f911b57ea 100644 > > --- a/drivers/net/ethernet/intel/iavf/iavf_main.c > > +++ b/drivers/net/ethernet/intel/iavf/iavf_main.c > > @@ -2877,6 +2877,13 @@ static void iavf_reset_task(struct work_struct > > *work) > > int i = 0, err; > > bool running; > > > > + /* > > + * Detach interface to avoid subsequent NDO callbacks > > + */ > > nit: > The comment should start this way: /* Detach ... Will fix. > > + rtnl_lock(); > > + netif_device_detach(netdev); > > + rtnl_unlock(); > > + > > /* When device is being removed it doesn't make sense to run the reset > > * task, just return in such a case. > > */ > > @@ -2884,7 +2891,7 @@ static void iavf_reset_task(struct work_struct *work) > > if (adapter->state != __IAVF_REMOVE) > > queue_work(iavf_wq, &adapter->reset_task); > > > > - return; > > + goto reset_finish; > > Correct me if I'm wrong. > In case when you fail to grab a crit_lock you'd jump to the reset_finish label and unlock the locks you didn't lock. You're right.. I tried to dedup mutex unlocks after testing and missed this path. Will fix by v2. Thanks, I. > > } > > > > while (!mutex_trylock(&adapter->client_lock)) > > @@ -2954,7 +2961,6 @@ static void iavf_reset_task(struct work_struct *work) > > > > if (running) { > > netif_carrier_off(netdev); > > - netif_tx_stop_all_queues(netdev); > > adapter->link_up = false; > > iavf_napi_disable_all(adapter); > > } > > @@ -3081,10 +3087,8 @@ static void iavf_reset_task(struct work_struct > > *work) > > > > adapter->flags &= ~IAVF_FLAG_REINIT_ITR_NEEDED; > > > > - mutex_unlock(&adapter->client_lock); > > - mutex_unlock(&adapter->crit_lock); > > + goto reset_finish; > > > > - return; > > reset_err: > > if (running) { > > set_bit(__IAVF_VSI_DOWN, adapter->vsi.state); @@ -3092,9 > > +3096,15 @@ static void iavf_reset_task(struct work_struct *work) > > } > > iavf_disable_vf(adapter); > > > > + dev_err(&adapter->pdev->dev, "failed to allocate resources during > > +reinit\n"); > > + > > +reset_finish: > > mutex_unlock(&adapter->client_lock); > > mutex_unlock(&adapter->crit_lock); > > - dev_err(&adapter->pdev->dev, "failed to allocate resources during > > reinit\n"); > > + > > + rtnl_lock(); > > + netif_device_attach(netdev); > > + rtnl_unlock(); > > } > > > > /** > > -- > > 2.35.1 >
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