Commit a3651bce authored by Michał Winiarski's avatar Michał Winiarski Committed by Wen Zhiwei
Browse files

drm: Expand max DRM device number to full MINORBITS 

stable inclusion
from stable-v6.6.53
commit e615cd84dcf834e83b333bfb690fc2032b3fdb85
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IAZ0GM

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e615cd84dcf834e83b333bfb690fc2032b3fdb85



--------------------------------

[ 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: default avatarMichał Winiarski <michal.winiarski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240823163048.2676257-4-michal.winiarski@intel.com


Acked-by: default avatarJames Zhu <James.Zhu@amd.com>
Acked-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarWen Zhiwei <wenzhiwei@kylinos.cn>
parent f7aba0dd

drivers/gpu/drm/drm_drv.c

+12 −0
Original line number Diff line number Diff line
@@ -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;