This is a note to let you know that I've just added the patch titled
drm: Expand max DRM device number to full MINORBITS
to the 6.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-expand-max-drm-device-number-to-full-minorbits.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e5b3b380b671294816499f105b3a348e68799cec
Author: Michał Winiarski <michal.winiarski@xxxxxxxxx>
Date: Fri Aug 23 18:30:48 2024 +0200
drm: Expand max DRM device number to full MINORBITS
[ Upstream commit 071d583e01c88272f6ff216d4f867f8f35e94d7d ]
Having a limit of 64 DRM devices is not good enough for modern world
where we have multi-GPU servers, SR-IOV virtual functions and virtual
devices used for testing.
Let's utilize full minor range for DRM devices.
To avoid regressing the existing userspace, we're still maintaining the
numbering scheme where 0-63 is used for primary, 64-127 is reserved
(formerly for control) and 128-191 is used for render.
For minors >= 192, we're allocating minors dynamically on a first-come,
first-served basis.
Signed-off-by: Michał Winiarski <michal.winiarski@xxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20240823163048.2676257-4-michal.winiarski@xxxxxxxxx
Acked-by: James Zhu <James.Zhu@xxxxxxx>
Acked-by: Christian König <christian.koenig@xxxxxxx>
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 7e0fa5a2a3182..c734e6a1c4ce2 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -121,10 +121,19 @@ static void drm_minor_alloc_release(struct drm_device *dev, void *data)
xa_erase(drm_minor_get_xa(minor->type), minor->index);
}
+/*
+ * DRM used to support 64 devices, for backwards compatibility we need to maintain the
+ * minor allocation scheme where minors 0-63 are primary nodes, 64-127 are control nodes,
+ * and 128-191 are render nodes.
+ * After reaching the limit, we're allocating minors dynamically - first-come, first-serve.
+ * Accel nodes are using a distinct major, so the minors are allocated in continuous 0-MAX
+ * range.
+ */
#define DRM_MINOR_LIMIT(t) ({ \
typeof(t) _t = (t); \
_t == DRM_MINOR_ACCEL ? XA_LIMIT(0, ACCEL_MAX_MINORS) : XA_LIMIT(64 * _t, 64 * _t + 63); \
})
+#define DRM_EXTENDED_MINOR_LIMIT XA_LIMIT(192, (1 << MINORBITS) - 1)
static int drm_minor_alloc(struct drm_device *dev, enum drm_minor_type type)
{
@@ -140,6 +149,9 @@ static int drm_minor_alloc(struct drm_device *dev, enum drm_minor_type type)
r = xa_alloc(drm_minor_get_xa(type), &minor->index,
NULL, DRM_MINOR_LIMIT(type), GFP_KERNEL);
+ if (r == -EBUSY && (type == DRM_MINOR_PRIMARY || type == DRM_MINOR_RENDER))
+ r = xa_alloc(&drm_minors_xa, &minor->index,
+ NULL, DRM_EXTENDED_MINOR_LIMIT, GFP_KERNEL);
if (r < 0)
return r;
