On 12/27/2016 03:44 AM, Kweh, Hock Leong wrote: > From: "Kweh, Hock Leong" <hock.leong.k...@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. -- Florian
