Re: Linux 5.1.9 build failure with CONFIG_NOUVEAU_LEGACY_CTX_SUPPORT=n

[Thomas Backlund]

Den 13-06-2019 kl. 10:42, skrev Greg Kroah-Hartman:

> I've just reverted it now.
>
> If someone can send me a patch series of all of what needs to be
> applied, in a format that I can actually apply them in, I will be glad
> to do so.  But for now, I'd like to get people's systems building again.


That would be basically re-adding the b30a43ac7132 commit and adding the 
following patch (also attached in case the inlined version gets mangled):

From 0d91b155a7f9c1f4a2b360bc2b79dc728aee8b48 Mon Sep 17 00:00:00 2001
From: Thomas Backlund <tmb@xxxxxxxxxx>
Date: Sat, 15 Jun 2019 12:22:44 +0300
Subject: [PATCH] nouveau: Fix build with 
CONFIG_NOUVEAU_LEGACY_CTX_SUPPORT disabled

Not-entirely-upstream-sha1-but-equivalent: bed2dd8421
("drm/ttm: Quick-test mmap offset in ttm_bo_mmap()")

Setting CONFIG_NOUVEAU_LEGACY_CTX_SUPPORT=n (added by commit: b30a43ac7132)
causes the build to fail with:

ERROR: "drm_legacy_mmap" [drivers/gpu/drm/nouveau/nouveau.ko] undefined!

This does not happend upstream as the offending code got removed in:
bed2dd8421 ("drm/ttm: Quick-test mmap offset in ttm_bo_mmap()")

Fix that by adding check for CONFIG_NOUVEAU_LEGACY_CTX_SUPPORT around
the drm_legacy_mmap() call.

Also, as Sven Joachim pointed out, we need to make the check in
CONFIG_NOUVEAU_LEGACY_CTX_SUPPORT=n case return -EINVAL as its done
for basically all other gpu drivers, especially in upstream kernels
drivers/gpu/drm/ttm/ttm_bo_vm.c as of the upstream commit bed2dd8421.

NOTE. This is a minimal stable-only fix for trees where b30a43ac7132 is
backported as the build error affects nouveau only.

Fixes: b30a43ac7132 ("drm/nouveau: add kconfig option to turn off nouveau
       legacy contexts. (v3)")
Signed-off-by: Thomas Backlund <tmb@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Sven Joachim <svenjoac@xxxxxx>
---
 drivers/gpu/drm/nouveau/nouveau_ttm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nouveau_ttm.c 
b/drivers/gpu/drm/nouveau/nouveau_ttm.c
index 1543c2f8d3d3..05d513d54555 100644
--- a/drivers/gpu/drm/nouveau/nouveau_ttm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_ttm.c
@@ -169,7 +169,11 @@ nouveau_ttm_mmap(struct file *filp, struct 
vm_area_struct *vma)
 	struct nouveau_drm *drm = nouveau_drm(file_priv->minor->dev);

 	if (unlikely(vma->vm_pgoff < DRM_FILE_PAGE_OFFSET))
+#if defined(CONFIG_NOUVEAU_LEGACY_CTX_SUPPORT)
 		return drm_legacy_mmap(filp, vma);
+#else
+		return -EINVAL;
+#endif

 	return ttm_bo_mmap(filp, vma, &drm->ttm.bdev);
 }
--
2.21.0