Messages in this thread | | | Subject | Re: [PATCH NET v3 1/2] net: phy: Add phy loopback support in net phy framework | From | Yunsheng Lin <> | Date | Sat, 24 Jun 2017 14:15:27 +0800 |
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On 2017/6/24 11:40, Yunsheng Lin wrote: > Hi, Andrew > > On 2017/6/24 11:12, Andrew Lunn wrote: >>> +int phy_loopback(struct phy_device *phydev, bool enable) >>> +{ >>> + struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver); >>> + int ret = 0; >>> + >>> + if (enable && phydev->loopback_enabled) >>> + return -EBUSY; >>> + >>> + if (!enable && !phydev->loopback_enabled) >>> + return -EINVAL; >>> + >>> + if (phydev->drv && phydrv->set_loopback) >>> + ret = phydrv->set_loopback(phydev, enable); >> >> else >> ret = -EOPNOTSUPP; >> >>> + >>> + if (ret) >>> + return ret; >>> + >>> + phydev->loopback_enabled = enable; >>> + >>> + return 0; >>> +} >>> +EXPORT_SYMBOL(phy_loopback); >> >> One of the comments we made of the PHY code in the hns driver is that >> its locking is completely broken. You have made the same error >> here. The core needs to hold the mutex while calling into the PHY >> driver. > Do you mean hns_nic_config_phy_loopback need to hold the mutex while > calling phy_loopback? and other place that calling phy_* function? I took some time looking into how to take mutex in phy core, here is what I find: phy_resume call phydrv->resume without take mutex. if phy driver implement resume function, for example marvell_resume, then
static int marvell_resume(struct phy_device *phydev) { int err;
/* Resume the fiber mode first */ if (!(phydev->supported & SUPPORTED_FIBRE)) { err = phy_write(phydev, MII_MARVELL_PHY_PAGE, MII_M1111_FIBER); if (err < 0) goto error;
/* With the page set, use the generic resume */ err = genphy_resume(phydev); if (err < 0) goto error;
/* Then, the copper link */ err = phy_write(phydev, MII_MARVELL_PHY_PAGE, MII_M1111_COPPER); if (err < 0) goto error; }
the code above executes without holding a mutex expect genphy_resume
/* With the page set, use the generic resume */ return genphy_resume(phydev);
error: phy_write(phydev, MII_MARVELL_PHY_PAGE, MII_M1111_COPPER); return err; }
So I think the correct way to hold a lock is in phy_* function, not in genphy_*, and current genphy_resume and phy_resume is broken in this way. Please let me know if I misunderstand the mutex taking in phy core.
Best Regards Yunsheng Lin
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