[PATCH v2 2/3] phy: rockchip-pcie: Use devm_clk_get_enabled() helper

[Anand Moon]

Hi Dan,

Thanks for the report.

On Wed, 9 Oct 2024 at 17:55, Dan Carpenter <dan.carpenter at linaro.org> wrote:
>
> Hi Anand,
>
> kernel test robot noticed the following build warnings:
>
> url:    https://github.com/intel-lab-lkp/linux/commits/Anand-Moon/phy-rockchip-pcie-Simplify-error-handling-with-dev_err_probe/20241007-115910
> base:   8f602276d3902642fdc3429b548d73c745446601
> patch link:    https://lore.kernel.org/r/20241007035616.2701-3-linux.amoon%40gmail.com
> patch subject: [PATCH v2 2/3] phy: rockchip-pcie: Use devm_clk_get_enabled() helper
> config: loongarch-randconfig-r071-20241009 (https://download.01.org/0day-ci/archive/20241009/202410092019.vGogfPIO-lkp@intel.com/config)
> compiler: loongarch64-linux-gcc (GCC) 14.1.0
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp at intel.com>
> | Reported-by: Dan Carpenter <dan.carpenter at linaro.org>
> | Closes: https://lore.kernel.org/r/202410092019.vGogfPIO-lkp@intel.com/
>
> smatch warnings:
> drivers/phy/rockchip/phy-rockchip-pcie.c:278 rockchip_pcie_phy_init() warn: missing error code 'err'
>

All the functions in this file explicitly return 0 instead of err, I
will fix this.

> vim +/err +278 drivers/phy/rockchip/phy-rockchip-pcie.c
>
> fcffee3d54fcad drivers/phy/phy-rockchip-pcie.c          Shawn Lin  2016-09-01  269  static int rockchip_pcie_phy_init(struct phy *phy)
> fcffee3d54fcad drivers/phy/phy-rockchip-pcie.c          Shawn Lin  2016-09-01  270  {
> 90a7612d070d5c drivers/phy/rockchip/phy-rockchip-pcie.c Shawn Lin  2017-07-19  271      struct phy_pcie_instance *inst = phy_get_drvdata(phy);
> 90a7612d070d5c drivers/phy/rockchip/phy-rockchip-pcie.c Shawn Lin  2017-07-19  272      struct rockchip_pcie_phy *rk_phy = to_pcie_phy(inst);
> fcffee3d54fcad drivers/phy/phy-rockchip-pcie.c          Shawn Lin  2016-09-01  273      int err = 0;
> fcffee3d54fcad drivers/phy/phy-rockchip-pcie.c          Shawn Lin  2016-09-01  274
> 90a7612d070d5c drivers/phy/rockchip/phy-rockchip-pcie.c Shawn Lin  2017-07-19  275      mutex_lock(&rk_phy->pcie_mutex);
> 90a7612d070d5c drivers/phy/rockchip/phy-rockchip-pcie.c Shawn Lin  2017-07-19  276
> 90a7612d070d5c drivers/phy/rockchip/phy-rockchip-pcie.c Shawn Lin  2017-07-19  277      if (rk_phy->init_cnt++)
> 90a7612d070d5c drivers/phy/rockchip/phy-rockchip-pcie.c Shawn Lin  2017-07-19 @278              goto err_out;
>
> Originally, this path just unlocked at returned zero.
>
> 90a7612d070d5c drivers/phy/rockchip/phy-rockchip-pcie.c Shawn Lin  2017-07-19  279
> fcffee3d54fcad drivers/phy/phy-rockchip-pcie.c          Shawn Lin  2016-09-01  280      err = reset_control_assert(rk_phy->phy_rst);
> fcffee3d54fcad drivers/phy/phy-rockchip-pcie.c          Shawn Lin  2016-09-01  281      if (err) {
> fcffee3d54fcad drivers/phy/phy-rockchip-pcie.c          Shawn Lin  2016-09-01  282              dev_err(&phy->dev, "assert phy_rst err %d\n", err);
> 3114329651e74f drivers/phy/rockchip/phy-rockchip-pcie.c Anand Moon 2024-10-07  283              goto err_out;
> fcffee3d54fcad drivers/phy/phy-rockchip-pcie.c          Shawn Lin  2016-09-01  284      }
> fcffee3d54fcad drivers/phy/phy-rockchip-pcie.c          Shawn Lin  2016-09-01  285
> 90a7612d070d5c drivers/phy/rockchip/phy-rockchip-pcie.c Shawn Lin  2017-07-19  286      mutex_unlock(&rk_phy->pcie_mutex);
> 90a7612d070d5c drivers/phy/rockchip/phy-rockchip-pcie.c Shawn Lin  2017-07-19  287      return 0;
> fcffee3d54fcad drivers/phy/phy-rockchip-pcie.c          Shawn Lin  2016-09-01  288
> 3114329651e74f drivers/phy/rockchip/phy-rockchip-pcie.c Anand Moon 2024-10-07  289  err_out:
> 90a7612d070d5c drivers/phy/rockchip/phy-rockchip-pcie.c Shawn Lin  2017-07-19  290      rk_phy->init_cnt--;
>
> Now it decrements the counter so presumably it leads to an underflow/use after
> free.

I was planning to replace the mutex_lock / mutex_unlock
with guard(mutex)(&rk_phy->pcie_mutex) in the follow up patch.
I will add this in the next revision.

>
> 90a7612d070d5c drivers/phy/rockchip/phy-rockchip-pcie.c Shawn Lin  2017-07-19  291      mutex_unlock(&rk_phy->pcie_mutex);
> fcffee3d54fcad drivers/phy/phy-rockchip-pcie.c          Shawn Lin  2016-09-01  292      return err;
> fcffee3d54fcad drivers/phy/phy-rockchip-pcie.c          Shawn Lin  2016-09-01  293  }
>

Here are my modified changes on top of my changes for the review process.
-----8<----------8<----------8<----------8<----------8<----------8<-----
diff --git a/drivers/phy/rockchip/phy-rockchip-pcie.c
b/drivers/phy/rockchip/phy-rockchip-pcie.c
index 2c4d6f68f02a..09685dc3fe17 100644
--- a/drivers/phy/rockchip/phy-rockchip-pcie.c
+++ b/drivers/phy/rockchip/phy-rockchip-pcie.c
@@ -248,20 +248,19 @@ static int rockchip_pcie_phy_init(struct phy *phy)

        mutex_lock(&rk_phy->pcie_mutex);

-       if (rk_phy->init_cnt++)
-               goto err_out;
+       if (rk_phy->init_cnt++) {
+               mutex_unlock(&rk_phy->pcie_mutex);
+               return err;
+       }

        err = reset_control_assert(rk_phy->phy_rst);
        if (err) {
                dev_err(&phy->dev, "assert phy_rst err %d\n", err);
-               goto err_out;
+               rk_phy->init_cnt--;
+               mutex_unlock(&rk_phy->pcie_mutex);
+               return err;
        }

-       mutex_unlock(&rk_phy->pcie_mutex);
-       return 0;
-
-err_out:
-       rk_phy->init_cnt--;
        mutex_unlock(&rk_phy->pcie_mutex);
        return err;
 }

Thanks
-Anand