From ff722da1fd9bd5c1cae93fbdc35deb71318c0812 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 9 Mar 2020 12:15:29 +0000
Subject: drm/mm: Allow drm_mm_initialized() to be used outside of the locks
Git-commit: 2214ddc2fda78bf48a3c36bcb4c8b9a95203049c
Patch-mainline: v5.7-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
Mark up the potential racy read in drm_mm_initialized(), as we want a
cheap and cheerful check:
[ 121.098731] BUG: KCSAN: data-race in _i915_gem_object_create_stolen [i915] / rm_hole
[ 121.098766]
[ 121.098789] write (marked) to 0xffff8881f01ed330 of 8 bytes by task 3568 on cpu 3:
[ 121.098831] rm_hole+0x64/0x140
[ 121.098860] drm_mm_insert_node_in_range+0x3d3/0x6c0
[ 121.099254] i915_gem_stolen_insert_node_in_range+0x91/0xe0 [i915]
[ 121.099646] _i915_gem_object_create_stolen+0x9d/0x100 [i915]
[ 121.100047] i915_gem_object_create_region+0x7a/0xa0 [i915]
[ 121.100451] i915_gem_object_create_stolen+0x33/0x50 [i915]
[ 121.100849] intel_engine_create_ring+0x1af/0x280 [i915]
[ 121.101242] __execlists_context_alloc+0xce/0x3d0 [i915]
[ 121.101635] execlists_context_alloc+0x25/0x40 [i915]
[ 121.102030] intel_context_alloc_state+0xb6/0xf0 [i915]
[ 121.102420] __intel_context_do_pin+0x1ff/0x220 [i915]
[ 121.102815] i915_gem_do_execbuffer+0x46b4/0x4c20 [i915]
[ 121.103211] i915_gem_execbuffer2_ioctl+0x2c3/0x580 [i915]
[ 121.103244] drm_ioctl_kernel+0xe4/0x120
[ 121.103269] drm_ioctl+0x297/0x4c7
[ 121.103296] ksys_ioctl+0x89/0xb0
[ 121.103321] __x64_sys_ioctl+0x42/0x60
[ 121.103349] do_syscall_64+0x6e/0x2c0
[ 121.103377] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 121.103403]
[ 121.103426] read to 0xffff8881f01ed330 of 8 bytes by task 3109 on cpu 1:
[ 121.103819] _i915_gem_object_create_stolen+0x30/0x100 [i915]
[ 121.104228] i915_gem_object_create_region+0x7a/0xa0 [i915]
[ 121.104631] i915_gem_object_create_stolen+0x33/0x50 [i915]
[ 121.105025] intel_engine_create_ring+0x1af/0x280 [i915]
[ 121.105420] __execlists_context_alloc+0xce/0x3d0 [i915]
[ 121.105818] execlists_context_alloc+0x25/0x40 [i915]
[ 121.106202] intel_context_alloc_state+0xb6/0xf0 [i915]
[ 121.106595] __intel_context_do_pin+0x1ff/0x220 [i915]
[ 121.106985] i915_gem_do_execbuffer+0x46b4/0x4c20 [i915]
[ 121.107375] i915_gem_execbuffer2_ioctl+0x2c3/0x580 [i915]
[ 121.107409] drm_ioctl_kernel+0xe4/0x120
[ 121.107437] drm_ioctl+0x297/0x4c7
[ 121.107464] ksys_ioctl+0x89/0xb0
[ 121.107489] __x64_sys_ioctl+0x42/0x60
[ 121.107511] do_syscall_64+0x6e/0x2c0
[ 121.107535] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200309121529.16497-1-chris@chris-wilson.co.uk
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
include/drm/drm_mm.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
index d7939c054259..ee8b0e80ca90 100644
--- a/include/drm/drm_mm.h
+++ b/include/drm/drm_mm.h
@@ -272,7 +272,7 @@ static inline bool drm_mm_node_allocated(const struct drm_mm_node *node)
*/
static inline bool drm_mm_initialized(const struct drm_mm *mm)
{
- return mm->hole_stack.next;
+ return READ_ONCE(mm->hole_stack.next);
}
/**
--
2.28.0