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    SubjectRe: [PATCH v6] staging: atomisp: move null check to earlier point
    Hello Andy,

    Can I get some feedback on v6 please?

    I hope it suits your standards this time.

    Thank you

    On August 2, 2020 01:02:22 Cengiz Can <cengiz@kernel.wtf> wrote:

    > `find_gmin_subdev()` that returns a pointer to `struct
    > gmin_subdev` can return NULL.
    >
    > In `gmin_v2p8_ctrl()` there's a call to this function but the
    > possibility of a NULL was not checked before its being dereferenced,
    > i.e.:
    >
    > /* Acquired here --------v */
    > struct gmin_subdev *gs = find_gmin_subdev(subdev);
    >
    > /* v------Dereferenced here */
    > if (gs->v2p8_gpio >= 0) {
    > ...
    > }
    >
    > With this change we're null checking `find_gmin_subdev()` result
    > and we return an error if that's the case. We also WARN()
    > for the sake of debugging.
    >
    > Signed-off-by: Cengiz Can <cengiz@kernel.wtf>
    > Reported-by: Coverity Static Analyzer CID 1465536
    > Suggested-by: Mauro Carvalho Chehab <mchehab@kernel.org>
    > ---
    >
    > Please do note that this change introduces a new return value to
    > `gmin_v2p8_ctrl()`.
    >
    > [NEW] - raise a WARN and return -ENODEV if there are no subdevices.
    > - return result of `gpio_request` or `gpio_direction_output`.
    > - return 0 if GPIO is ON.
    > - return results of `regulator_enable` or `regulator_disable`.
    > - according to PMIC type, return result of `axp_regulator_set`
    > or `gmin_i2c_write`.
    > - return -EINVAL if unknown PMIC type.
    >
    > Patch Changelog:
    > v4: Fix minor typo in commit message
    > v5: Remove typo from email subject
    > v6: Remove duplicate Signed-off-by tag
    >
    > drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c | 5 ++++-
    > 1 file changed, 4 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
    > b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
    > index 0df46a1af5f0..1ad0246764a6 100644
    > --- a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
    > +++ b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
    > @@ -871,6 +871,9 @@ static int gmin_v2p8_ctrl(struct v4l2_subdev *subdev,
    > int on)
    > int ret;
    > int value;
    >
    > + if (WARN_ON(!gs))
    > + return -ENODEV;
    > +
    > if (gs->v2p8_gpio >= 0) {
    > pr_info("atomisp_gmin_platform: 2.8v power on GPIO %d\n",
    > gs->v2p8_gpio);
    > @@ -881,7 +884,7 @@ static int gmin_v2p8_ctrl(struct v4l2_subdev *subdev,
    > int on)
    > pr_err("V2P8 GPIO initialization failed\n");
    > }
    >
    > - if (!gs || gs->v2p8_on == on)
    > + if (gs->v2p8_on == on)
    > return 0;
    > gs->v2p8_on = on;
    >
    > --
    > 2.27.0



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