答复: [PATCH] net: fec: Fix reference count leak in fec series ops

[zhangqilong]

> From: zhangqilong <zhangqilo...@huawei.com>ent: Monday, November 9,
> 2020 10:52 AM
> > > From: Zhang Qilong <zhangqilo...@huawei.com> Sent: Sunday, November
> > > 8,
> > > 2020 5:53 PM
> > > > pm_runtime_get_sync() will increment pm usage at first and it will
> > > > resume the device later. If runtime of the device has error or
> > > > device is in inaccessible state(or other error state), resume
> > > > operation will fail. If we do not call put operation to decrease
> > > > the reference, it will result in
> > > reference count leak.
> > > > Moreover, this device cannot enter the idle state and always stay
> > > > busy or other non-idle state later. So we fixed it through adding
> > > pm_runtime_put_noidle.
> > > >
> > > > Fixes: 8fff755e9f8d0 ("net: fec: Ensure clocks are enabled while
> > > > using mdio bus")
> > > > Signed-off-by: Zhang Qilong <zhangqilo...@huawei.com>
> > >
> > > From early discussion for the topic, Wolfram Sang wonder if such
> > > de-reference can be better handled by pm runtime core code.
> > >
> > I have read the discussion just now, They didn't give a definite
> > result. I agreed with introducing a new or help function to replace
> > the pm_runtime_get_sync gradually. How do you think so ?
> >
> > Regards,
> > Zhang
> 
> I also think so to avoid so much duplication code in function driver.

Hi,
 
I have added a more general operation in flowing patch
https://lore.kernel.org/netdev/20201109080938.4174745-1-zhangqilo...@huawei.com/T/#t
to solve this problem. Comments are welcome if you are free.

Regards,
Zhang

> >
> > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flk
> > >
> ml .org%2Flkml%2F2020%2F6%2F14%2F76&amp;data=04%7C01%7Cfugang.du
> a
> > n%40nxp.
> > >
> >
> com%7Ceaef5020d1c143dfda5208d8845a6391%7C686ea1d3bc2b4c6fa92cd99
> > c5c301
> > >
> >
> 635%7C0%7C0%7C637404871050135426%7CUnknown%7CTWFpbGZsb3d8eyJ
> > WIjoiMC4wL
> > >
> >
> jAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;
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> > data
> > >
> =GLi34HRLzzTnTjT54dpNXkMdvuPuyVhcSuAGqc1rdvw%3D&amp;reserved=0
> > >
> > > Regards,
> > > Andy
> > > > ---
> > > >  drivers/net/ethernet/freescale/fec_main.c | 22
> > > > ++++++++++++++++------
> > > >  1 file changed, 16 insertions(+), 6 deletions(-)
> > > >
> > > > diff --git a/drivers/net/ethernet/freescale/fec_main.c
> > > > b/drivers/net/ethernet/freescale/fec_main.c
> > > > index d7919555250d..6c02f885c67e 100644
> > > > --- a/drivers/net/ethernet/freescale/fec_main.c
> > > > +++ b/drivers/net/ethernet/freescale/fec_main.c
> > > > @@ -1809,8 +1809,10 @@ static int fec_enet_mdio_read(struct
> > > > mii_bus *bus, int mii_id, int regnum)
> > > >         bool is_c45 = !!(regnum & MII_ADDR_C45);
> > > >
> > > >         ret = pm_runtime_get_sync(dev);
> > > > -       if (ret < 0)
> > > > +       if (ret < 0) {
> > > > +               pm_runtime_put_noidle(dev);
> > > >                 return ret;
> > > > +       }
> > > >
> > > >         if (is_c45) {
> > > >                 frame_start = FEC_MMFR_ST_C45;
> > > > @@ -1868,10 +1870,12 @@ static int fec_enet_mdio_write(struct
> > > > mii_bus *bus, int mii_id, int regnum,
> > > >         bool is_c45 = !!(regnum & MII_ADDR_C45);
> > > >
> > > >         ret = pm_runtime_get_sync(dev);
> > > > -       if (ret < 0)
> > > > +       if (ret < 0) {
> > > > +               pm_runtime_put_noidle(dev);
> > > >                 return ret;
> > > > -       else
> > > > +       } else {
> > > >                 ret = 0;
> > > > +       }
> > > >
> > > >         if (is_c45) {
> > > >                 frame_start = FEC_MMFR_ST_C45;
> > > > @@ -2276,8 +2280,10 @@ static void fec_enet_get_regs(struct
> > > > net_device *ndev,
> > > >         int ret;
> > > >
> > > >         ret = pm_runtime_get_sync(dev);
> > > > -       if (ret < 0)
> > > > +       if (ret < 0) {
> > > > +               pm_runtime_put_noidle(dev);
> > > >                 return;
> > > > +       }
> > > >
> > > >         regs->version = fec_enet_register_version;
> > > >
> > > > @@ -2977,8 +2983,10 @@ fec_enet_open(struct net_device *ndev)
> > > >         bool reset_again;
> > > >
> > > >         ret = pm_runtime_get_sync(&fep->pdev->dev);
> > > > -       if (ret < 0)
> > > > +       if (ret < 0) {
> > > > +               pm_runtime_put_noidle(&fep->pdev->dev);
> > > >                 return ret;
> > > > +       }
> > > >
> > > >         pinctrl_pm_select_default_state(&fep->pdev->dev);
> > > >         ret = fec_enet_clk_enable(ndev, true); @@ -3771,8 +3779,10 @@
> > > > fec_drv_remove(struct platform_device *pdev)
> > > >         int ret;
> > > >
> > > >         ret = pm_runtime_get_sync(&pdev->dev);
> > > > -       if (ret < 0)
> > > > +       if (ret < 0) {
> > > > +               pm_runtime_put_noidle(&pdev->dev);
> > > >                 return ret;
> > > > +       }
> > > >
> > > >         cancel_work_sync(&fep->tx_timeout_work);
> > > >         fec_ptp_stop(pdev);
> > > > --
> > > > 2.25.4