Hi Sam,
> -----Original Message-----
> From: Sam Ravnborg <s...@ravnborg.org>
> Sent: Wednesday, July 28, 2021 12:27 AM
> To: Chrisanthus, Anitha <anitha.chrisant...@intel.com>
> Cc: dri-devel@lists.freedesktop.org; Dea, Edmund J
> <edmund.j....@intel.com>; Dan Carpenter <dan.carpen...@oracle.com>
> Subject: Re: [PATCH 12/14] drm/kmb: Fix possible oops in error handling
>
> Hi Anitha,
>
> On Tue, Jul 27, 2021 at 05:31:24PM -0700, Anitha Chrisanthus wrote:
> > If kmb_dsi_init() fails the "kmb->kmb_dsi" variable is an error pointer.
> > This can potentially result in kernel panic when kmb_dsi_host_unregister is
> > called.
> >
> > Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display")
> > Fixes: 98521f4d4b4c ("drm/kmb: Mipi DSI part of the display driver")
> > Cc: Dan Carpenter <dan.carpen...@oracle.com>
> > Signed-off-by: Anitha Chrisanthus <anitha.chrisant...@intel.com>
> > ---
> > drivers/gpu/drm/kmb/kmb_drv.c | 9 ++++++---
> > drivers/gpu/drm/kmb/kmb_dsi.c | 9 +++++----
> > drivers/gpu/drm/kmb/kmb_dsi.h | 3 ++-
> > 3 files changed, 13 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/kmb/kmb_drv.c
> b/drivers/gpu/drm/kmb/kmb_drv.c
> > index bb7eca9e13ae..12f35c43d838 100644
> > --- a/drivers/gpu/drm/kmb/kmb_drv.c
> > +++ b/drivers/gpu/drm/kmb/kmb_drv.c
> > @@ -454,8 +454,9 @@ static int kmb_remove(struct platform_device
> *pdev)
> > dev_set_drvdata(dev, NULL);
> >
> > /* Unregister DSI host */
> > - kmb_dsi_host_unregister(kmb->kmb_dsi);
> > + kmb_dsi_host_unregister();
> > drm_atomic_helper_shutdown(drm);
> > + drm_dev_put(drm);
> > return 0;
> > }
> >
> > @@ -519,7 +520,7 @@ static int kmb_probe(struct platform_device *pdev)
> > if (IS_ERR(kmb->kmb_dsi)) {
> > drm_err(&kmb->drm, "failed to initialize DSI\n");
> > ret = PTR_ERR(kmb->kmb_dsi);
> > - goto err_free1;
> > + goto err_free2;
> > }
> >
> > kmb->kmb_dsi->dev = &dsi_pdev->dev;
> > @@ -555,8 +556,10 @@ static int kmb_probe(struct platform_device *pdev)
> > drm_crtc_cleanup(&kmb->crtc);
> > drm_mode_config_cleanup(&kmb->drm);
> > err_free1:
> > + kmb_dsi_clk_disable(kmb->kmb_dsi);
> > + err_free2:
> > dev_set_drvdata(dev, NULL);
> > - kmb_dsi_host_unregister(kmb->kmb_dsi);
> > + kmb_dsi_host_unregister();
> >
>
> This really looks like a step backward. There should not be a eed to
> call unregister if kmb_dsi is not a valid pointer in the first place.
> Also drn_dev_put() should not be needed with the use of drmm
> infrastructure.
Agree, I was trying to address issues with Dan's original patch.
I will keep the original code, with only this change
if (IS_ERR(kmb->kmb_dsi)) {
drm_err(&kmb->drm, "failed to initialize DSI\n");
- ret = PTR_ERR(kmb->kmb_dsi);
- goto err_free2;
+ dev_set_drvdata(dev, NULL);
+ return PTR_ERR(kmb->kmb_dsi);
Will send v2
>
>
>
> > return ret;
> > }
> > diff --git a/drivers/gpu/drm/kmb/kmb_dsi.c
> b/drivers/gpu/drm/kmb/kmb_dsi.c
> > index 1cca0fe6f35f..a500172ada87 100644
> > --- a/drivers/gpu/drm/kmb/kmb_dsi.c
> > +++ b/drivers/gpu/drm/kmb/kmb_dsi.c
> > @@ -172,17 +172,17 @@
> mipi_hs_freq_range[MIPI_DPHY_DEFAULT_BIT_RATES] = {
> > {.default_bit_rate_mbps = 2500, .hsfreqrange_code = 0x49}
> > };
> >
> > -static void kmb_dsi_clk_disable(struct kmb_dsi *kmb_dsi)
> > +void kmb_dsi_clk_disable(struct kmb_dsi *kmb_dsi)
> > {
> > clk_disable_unprepare(kmb_dsi->clk_mipi);
> > clk_disable_unprepare(kmb_dsi->clk_mipi_ecfg);
> > clk_disable_unprepare(kmb_dsi->clk_mipi_cfg);
> > }
> >
> > -void kmb_dsi_host_unregister(struct kmb_dsi *kmb_dsi)
> > +void kmb_dsi_host_unregister(void)
> > {
> > - kmb_dsi_clk_disable(kmb_dsi);
> > - mipi_dsi_host_unregister(kmb_dsi->host);
> > + if (dsi_host)
> > + mipi_dsi_host_unregister(dsi_host);
> > }
> I thought we had killed the global dsi_host variable??
> Seems some cleanup is till needed here.
>
> Sam
