> -----Original Message----- > From: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> > Sent: Friday, August 26, 2022 2:11 PM > To: Vinod Polimera (QUIC) <quic_vpolimer@xxxxxxxxxxx>; dri- > devel@xxxxxxxxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx; > freedreno@xxxxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx; robdclark@xxxxxxxxx; > dianders@xxxxxxxxxxxx; vpolimer@xxxxxxxxxxx; swboyd@xxxxxxxxxxxx; > kalyant@xxxxxxxxxxx > Subject: Re: [v2] drm/msm: add null checks for drm device to avoid crash > during probe defer > > WARNING: This email originated from outside of Qualcomm. Please be wary > of any links or attachments, and do not enable macros. > > On 15/06/2022 15:23, Dmitry Baryshkov wrote: > > On 03/06/2022 12:42, Vinod Polimera wrote: > >> During probe defer, drm device is not initialized and an external > >> trigger to shutdown is trying to clean up drm device leading to crash. > >> Add checks to avoid drm device cleanup in such cases. > >> > >> BUG: unable to handle kernel NULL pointer dereference at virtual > >> address 00000000000000b8 > >> > >> Call trace: > >> > >> drm_atomic_helper_shutdown+0x44/0x144 > >> msm_pdev_shutdown+0x2c/0x38 > >> platform_shutdown+0x2c/0x38 > >> device_shutdown+0x158/0x210 > >> kernel_restart_prepare+0x40/0x4c > >> kernel_restart+0x20/0x6c > >> __arm64_sys_reboot+0x194/0x23c > >> invoke_syscall+0x50/0x13c > >> el0_svc_common+0xa0/0x17c > >> do_el0_svc_compat+0x28/0x34 > >> el0_svc_compat+0x20/0x70 > >> el0t_32_sync_handler+0xa8/0xcc > >> el0t_32_sync+0x1a8/0x1ac > >> > >> Changes in v2: > >> - Add fixes tag. > >> > >> Fixes: 623f279c778 ("drm/msm: fix shutdown hook in case GPU > components > >> failed to bind") > >> Signed-off-by: Vinod Polimera <quic_vpolimer@xxxxxxxxxxx> > >> --- > >> drivers/gpu/drm/msm/msm_drv.c | 6 +++++- > >> 1 file changed, 5 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/gpu/drm/msm/msm_drv.c > >> b/drivers/gpu/drm/msm/msm_drv.c > >> index 4448536..d62ac66 100644 > >> --- a/drivers/gpu/drm/msm/msm_drv.c > >> +++ b/drivers/gpu/drm/msm/msm_drv.c > >> @@ -142,6 +142,9 @@ static void msm_irq_uninstall(struct drm_device > *dev) > >> struct msm_drm_private *priv = dev->dev_private; > >> struct msm_kms *kms = priv->kms; > >> + if (!irq_has_action(kms->irq)) > >> + return; > > > > As a second thought I'd still prefer a variable here. irq_has_action > > would check that there is _any_ IRQ handler for this IRQ. While we do > > not have anybody sharing this IRQ, I'd prefer to be clear here, that we > > do not want to uninstall our IRQ handler rather than any IRQ handler. > > Vinod, do we still want to pursue this fix? If so, could you please > update it according to the comment. > I have looked up and found many kernel drivers are using Irq_has_action to see if the interrupt is requested, it appears to me as an aggregable way of doing it. Having a variable to track the state seems unnecessary as it needs to be managed race free. let me know your views on it. > > > >> + > >> kms->funcs->irq_uninstall(kms); > >> if (kms->irq_requested) > >> free_irq(kms->irq, dev); > >> @@ -259,6 +262,7 @@ static int msm_drm_uninit(struct device *dev) > >> ddev->dev_private = NULL; > >> drm_dev_put(ddev); > >> + priv->dev = NULL; > >> destroy_workqueue(priv->wq); > >> @@ -1167,7 +1171,7 @@ void msm_drv_shutdown(struct > platform_device *pdev) > >> struct msm_drm_private *priv = platform_get_drvdata(pdev); > >> struct drm_device *drm = priv ? priv->dev : NULL; > >> - if (!priv || !priv->kms) > >> + if (!priv || !priv->kms || !drm) > >> return; > >> drm_atomic_helper_shutdown(drm); > > > > > > -- > With best wishes > Dmitry - Vinod P.