Messages in this thread |  | | From | "Kweh, Hock Leong" <> | Subject | RE: [PATCH] net: stmmac: synchronize stmmac_open and stmmac_dvr_probe | Date | Tue, 27 Dec 2016 05:25:02 +0000 |
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> -----Original Message----- > From: Florian Fainelli [mailto:f.fainelli@gmail.com] > Sent: Tuesday, December 27, 2016 1:14 PM > To: Kweh, Hock Leong <hock.leong.kweh@intel.com>; David S. Miller > <davem@davemloft.net>; Joao Pinto <Joao.Pinto@synopsys.com>; Giuseppe > CAVALLARO <peppe.cavallaro@st.com>; seraphin.bonnaffe@st.com > Cc: Alexandre TORGUE <alexandre.torgue@gmail.com>; Joachim Eastwood > <manabian@gmail.com>; Niklas Cassel <niklas.cassel@axis.com>; Johan Hovold > <johan@kernel.org>; pavel@ucw.cz; Ong, Boon Leong > <boon.leong.ong@intel.com>; netdev <netdev@vger.kernel.org>; LKML <linux- > kernel@vger.kernel.org>; Voon, Weifeng <weifeng.voon@intel.com>; Lars > Persson <lars.persson@axis.com> > Subject: Re: [PATCH] net: stmmac: synchronize stmmac_open and > stmmac_dvr_probe > > > > On 12/26/2016 09:10 PM, Florian Fainelli wrote: > > > > > > On 12/27/2016 03:44 AM, Kweh, Hock Leong wrote: > >> From: "Kweh, Hock Leong" <hock.leong.kweh@intel.com> > >> > >> If kernel module stmmac driver being loaded after OS booted, there is a > >> race condition between stmmac_open() and stmmac_mdio_register(), which > is > >> invoked inside stmmac_dvr_probe(), and the error is showed in dmesg log as > >> PHY not found and stmmac_open() failed: > >> [ 473.919358] stmmaceth 0000:01:00.0 (unnamed net_device) (uninitialized): > >> stmmac_dvr_probe: warning: cannot get CSR clock > >> [ 473.919382] stmmaceth 0000:01:00.0: no reset control found > >> [ 473.919412] stmmac - user ID: 0x10, Synopsys ID: 0x42 > >> [ 473.919429] stmmaceth 0000:01:00.0: DMA HW capability register > supported > >> [ 473.919436] stmmaceth 0000:01:00.0: RX Checksum Offload Engine > supported > >> [ 473.919443] stmmaceth 0000:01:00.0: TX Checksum insertion supported > >> [ 473.919451] stmmaceth 0000:01:00.0 (unnamed net_device) (uninitialized): > >> Enable RX Mitigation via HW Watchdog Timer > >> [ 473.921395] libphy: PHY stmmac-1:00 not found > >> [ 473.921417] stmmaceth 0000:01:00.0 eth0: Could not attach to PHY > >> [ 473.921427] stmmaceth 0000:01:00.0 eth0: stmmac_open: Cannot attach > to > >> PHY (error: -19) > >> [ 473.959710] libphy: stmmac: probed > >> [ 473.959724] stmmaceth 0000:01:00.0 eth0: PHY ID 01410cc2 at 0 IRQ POLL > >> (stmmac-1:00) active > >> [ 473.959728] stmmaceth 0000:01:00.0 eth0: PHY ID 01410cc2 at 1 IRQ POLL > >> (stmmac-1:01) > >> [ 473.959731] stmmaceth 0000:01:00.0 eth0: PHY ID 01410cc2 at 2 IRQ POLL > >> (stmmac-1:02) > >> [ 473.959734] stmmaceth 0000:01:00.0 eth0: PHY ID 01410cc2 at 3 IRQ POLL > >> (stmmac-1:03) > >> > >> The resolution used wait_for_completion_interruptible() to synchronize > >> stmmac_open() and stmmac_dvr_probe() to prevent the race condition > >> happening. > > > > The proper fix for this would be to have register_netdev() be the last > > thing done in stmmac_drv_probe(), whereas right now, the last thing done > > is stmmac_mdio_register(), leading the window you are seeing here, where > > the network interface can be open prior to all resources being set up, > > including, but not limited to MDIO devices. > > Something like the following untested patch should plug this race: > > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > index bb40382e205d..5910ea51f8f6 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > @@ -3339,13 +3339,6 @@ int stmmac_dvr_probe(struct device *device, > > spin_lock_init(&priv->lock); > > - ret = register_netdev(ndev); > - if (ret) { > - netdev_err(priv->dev, "%s: ERROR %i registering the > device\n", > - __func__, ret); > - goto error_netdev_register; > - } > - > /* If a specific clk_csr value is passed from the platform > * this means that the CSR Clock Range selection cannot be > * changed at run-time and it is fixed. Viceversa the driver'll > try to > @@ -3372,11 +3365,14 @@ int stmmac_dvr_probe(struct device *device, > } > } > > - return 0; > + ret = register_netdev(ndev); > + if (ret) > + netdev_err(priv->dev, "%s: ERROR %i registering the > device\n", > + __func__, ret); > + > + return ret; > > error_mdio_register: > - unregister_netdev(ndev); > -error_netdev_register: > netif_napi_del(&priv->napi); > error_hw_init: > clk_disable_unprepare(priv->pclk); > > -- > Florian
Thanks. Will try out to confirm.
Regards, Wilson
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