This is a note to let you know that I've just added the patch titled
drm/vmwgfx: Fix a destoy-while-held mutex problem.
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: drm-vmwgfx-fix-a-destoy-while-held-mutex-problem.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 73a88250b70954a8f27c2444e1c2411bba3c29d9 Mon Sep 17 00:00:00 2001
From: Thomas Hellstrom thellstrom@vmware.com Date: Wed, 21 Mar 2018 10:18:38 +0100 Subject: drm/vmwgfx: Fix a destoy-while-held mutex problem.
From: Thomas Hellstrom thellstrom@vmware.com
commit 73a88250b70954a8f27c2444e1c2411bba3c29d9 upstream.
When validating legacy surfaces, the backup bo might be destroyed at surface validate time. However, the kms resource validation code may have the bo reserved, so we will destroy a locked mutex. While there shouldn't be any other users of that mutex when it is destroyed, it causes a lock leak and thus throws a lockdep error.
Fix this by having the kms resource validation code hold a reference to the bo while we have it reserved. We do this by introducing a validation context which might come in handy when the kms code is extended to validate multiple resources or buffers.
Cc: stable@vger.kernel.org Signed-off-by: Thomas Hellstrom thellstrom@vmware.com Reviewed-by: Brian Paul brianp@vmware.com Reviewed-by: Sinclair Yeh syeh@vmware.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 28 +++++++++++++++++++--------- drivers/gpu/drm/vmwgfx/vmwgfx_kms.h | 12 +++++++++--- drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c | 5 +++-- drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c | 5 +++-- 4 files changed, 34 insertions(+), 16 deletions(-)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c @@ -27,7 +27,6 @@
#include "vmwgfx_kms.h"
- /* Might need a hrtimer here? */ #define VMWGFX_PRESENT_RATE ((HZ / 60 > 0) ? HZ / 60 : 1)
@@ -1910,9 +1909,12 @@ void vmw_kms_helper_buffer_finish(struct * Helper to be used if an error forces the caller to undo the actions of * vmw_kms_helper_resource_prepare. */ -void vmw_kms_helper_resource_revert(struct vmw_resource *res) +void vmw_kms_helper_resource_revert(struct vmw_validation_ctx *ctx) { - vmw_kms_helper_buffer_revert(res->backup); + struct vmw_resource *res = ctx->res; + + vmw_kms_helper_buffer_revert(ctx->buf); + vmw_dmabuf_unreference(&ctx->buf); vmw_resource_unreserve(res, false, NULL, 0); mutex_unlock(&res->dev_priv->cmdbuf_mutex); } @@ -1929,10 +1931,14 @@ void vmw_kms_helper_resource_revert(stru * interrupted by a signal. */ int vmw_kms_helper_resource_prepare(struct vmw_resource *res, - bool interruptible) + bool interruptible, + struct vmw_validation_ctx *ctx) { int ret = 0;
+ ctx->buf = NULL; + ctx->res = res; + if (interruptible) ret = mutex_lock_interruptible(&res->dev_priv->cmdbuf_mutex); else @@ -1951,6 +1957,8 @@ int vmw_kms_helper_resource_prepare(stru res->dev_priv->has_mob); if (ret) goto out_unreserve; + + ctx->buf = vmw_dmabuf_reference(res->backup); } ret = vmw_resource_validate(res); if (ret) @@ -1958,7 +1966,7 @@ int vmw_kms_helper_resource_prepare(stru return 0;
out_revert: - vmw_kms_helper_buffer_revert(res->backup); + vmw_kms_helper_buffer_revert(ctx->buf); out_unreserve: vmw_resource_unreserve(res, false, NULL, 0); out_unlock: @@ -1974,11 +1982,13 @@ out_unlock: * @out_fence: Optional pointer to a fence pointer. If non-NULL, a * ref-counted fence pointer is returned here. */ -void vmw_kms_helper_resource_finish(struct vmw_resource *res, - struct vmw_fence_obj **out_fence) +void vmw_kms_helper_resource_finish(struct vmw_validation_ctx *ctx, + struct vmw_fence_obj **out_fence) { - if (res->backup || out_fence) - vmw_kms_helper_buffer_finish(res->dev_priv, NULL, res->backup, + struct vmw_resource *res = ctx->res; + + if (ctx->buf || out_fence) + vmw_kms_helper_buffer_finish(res->dev_priv, NULL, ctx->buf, out_fence, NULL);
vmw_resource_unreserve(res, false, NULL, 0); --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h @@ -180,6 +180,11 @@ struct vmw_display_unit { bool is_implicit; };
+struct vmw_validation_ctx { + struct vmw_resource *res; + struct vmw_dma_buffer *buf; +}; + #define vmw_crtc_to_du(x) \ container_of(x, struct vmw_display_unit, crtc) #define vmw_connector_to_du(x) \ @@ -230,9 +235,10 @@ void vmw_kms_helper_buffer_finish(struct struct drm_vmw_fence_rep __user * user_fence_rep); int vmw_kms_helper_resource_prepare(struct vmw_resource *res, - bool interruptible); -void vmw_kms_helper_resource_revert(struct vmw_resource *res); -void vmw_kms_helper_resource_finish(struct vmw_resource *res, + bool interruptible, + struct vmw_validation_ctx *ctx); +void vmw_kms_helper_resource_revert(struct vmw_validation_ctx *ctx); +void vmw_kms_helper_resource_finish(struct vmw_validation_ctx *ctx, struct vmw_fence_obj **out_fence); int vmw_kms_readback(struct vmw_private *dev_priv, struct drm_file *file_priv, --- a/drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c @@ -841,12 +841,13 @@ int vmw_kms_sou_do_surface_dirty(struct struct vmw_framebuffer_surface *vfbs = container_of(framebuffer, typeof(*vfbs), base); struct vmw_kms_sou_surface_dirty sdirty; + struct vmw_validation_ctx ctx; int ret;
if (!srf) srf = &vfbs->surface->res;
- ret = vmw_kms_helper_resource_prepare(srf, true); + ret = vmw_kms_helper_resource_prepare(srf, true, &ctx); if (ret) return ret;
@@ -865,7 +866,7 @@ int vmw_kms_sou_do_surface_dirty(struct ret = vmw_kms_helper_dirty(dev_priv, framebuffer, clips, vclips, dest_x, dest_y, num_clips, inc, &sdirty.base); - vmw_kms_helper_resource_finish(srf, out_fence); + vmw_kms_helper_resource_finish(&ctx, out_fence);
return ret; } --- a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c @@ -1003,12 +1003,13 @@ int vmw_kms_stdu_surface_dirty(struct vm struct vmw_framebuffer_surface *vfbs = container_of(framebuffer, typeof(*vfbs), base); struct vmw_stdu_dirty sdirty; + struct vmw_validation_ctx ctx; int ret;
if (!srf) srf = &vfbs->surface->res;
- ret = vmw_kms_helper_resource_prepare(srf, true); + ret = vmw_kms_helper_resource_prepare(srf, true, &ctx); if (ret) return ret;
@@ -1031,7 +1032,7 @@ int vmw_kms_stdu_surface_dirty(struct vm dest_x, dest_y, num_clips, inc, &sdirty.base); out_finish: - vmw_kms_helper_resource_finish(srf, out_fence); + vmw_kms_helper_resource_finish(&ctx, out_fence);
return ret; }
Patches currently in stable-queue which might be from thellstrom@vmware.com are
queue-4.4/drm-vmwgfx-fix-a-destoy-while-held-mutex-problem.patch