Hi Icenowy, Thomas, Thanks for the review.
I agree that using drmm_kms_helper_poll_init() is the better fix here. It keeps the polling cleanup tied to the DRM device lifetime and avoids adding manual unwind and remove-path cleanup. I sent a v2 that switches lsdc_pci_probe() to drmm_kms_helper_poll_init(). Thanks, Myeonghun 2026년 5월 12일 (화) 오후 3:26, Thomas Zimmermann <[email protected]>님이 작성: > Hi > > Am 11.05.26 um 19:22 schrieb Icenowy Zheng: > > 在 2026-05-12二的 02:01 +0900，Myeonghun Pak写道： > >> lsdc_pci_probe() initializes KMS polling before setting up vblank > >> support, > >> requesting the IRQ and registering the DRM device. If any of those > >> later > >> steps fails, probe returns without finalizing polling. The remove > >> path has > >> the same lifetime gap when tearing down a successfully registered > >> device. > >> > >> Route those probe failures through a poll cleanup label. Also > >> finalize > >> polling from remove before unregistering the DRM device. > > Interesting, but it looks like a `drmm_kms_helper_poll_init` function > > exists (while rarely used). > > > > Maybe it's better to switch to this? Or maybe there's some reason not > > to use this? > > Agreed. DRM drivers are advised to use managed cleanup for their data > structures. So rather switch to drmm_kms_helper_poll_init(). That also > resolves the problem that loongson never calls poll_fini on regular > removals. > > Best regards > Thomas > > > > > Thanks, > > Icenowy > > > >> This issue was identified during our ongoing static-analysis research > >> while > >> reviewing kernel code. > >> > >> Fixes: f39db26c5428 ("drm: Add kms driver for loongson display > >> controller") > >> Cc: [email protected] > >> Co-developed-by: Ijae Kim <[email protected]> > >> Signed-off-by: Ijae Kim <[email protected]> > >> Signed-off-by: Myeonghun Pak <[email protected]> > >> --- > >> drivers/gpu/drm/loongson/lsdc_drv.c | 11 ++++++++--- > >> 1 file changed, 8 insertions(+), 3 deletions(-) > >> > >> diff --git a/drivers/gpu/drm/loongson/lsdc_drv.c > >> b/drivers/gpu/drm/loongson/lsdc_drv.c > >> index abf5bf68ee..3db1f8690a 100644 > >> --- a/drivers/gpu/drm/loongson/lsdc_drv.c > >> +++ b/drivers/gpu/drm/loongson/lsdc_drv.c > >> @@ -297,7 +297,7 @@ static int lsdc_pci_probe(struct pci_dev *pdev, > >> const struct pci_device_id *ent) > >> if (loongson_vblank) { > >> ret = drm_vblank_init(ddev, descp->num_of_crtc); > >> if (ret) > >> - return ret; > >> + goto err_poll_fini; > >> > >> ret = devm_request_irq(&pdev->dev, pdev->irq, > >> descp->funcs->irq_handler, > >> @@ -305,7 +305,7 @@ static int lsdc_pci_probe(struct pci_dev *pdev, > >> const struct pci_device_id *ent) > >> dev_name(&pdev->dev), ddev); > >> if (ret) { > >> drm_err(ddev, "Failed to register interrupt: > >> %d\n", ret); > >> - return ret; > >> + goto err_poll_fini; > >> } > >> > >> drm_info(ddev, "registered irq: %u\n", pdev->irq); > >> @@ -313,17 +313,22 @@ static int lsdc_pci_probe(struct pci_dev *pdev, > >> const struct pci_device_id *ent) > >> > >> ret = drm_dev_register(ddev, 0); > >> if (ret) > >> - return ret; > >> + goto err_poll_fini; > >> > >> drm_client_setup(ddev, NULL); > >> > >> return 0; > >> + > >> +err_poll_fini: > >> + drm_kms_helper_poll_fini(ddev); > >> + return ret; > >> } > >> > >> static void lsdc_pci_remove(struct pci_dev *pdev) > >> { > >> struct drm_device *ddev = pci_get_drvdata(pdev); > >> > >> + drm_kms_helper_poll_fini(ddev); > >> drm_dev_unregister(ddev); > >> drm_atomic_helper_shutdown(ddev); > >> } > > -- > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com > GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG > Nürnberg) > > >
