[Intel-gfx] [PATCH] drm/locking: Allow NULL crtc in drm_modeset_legacy_acquire_ctx
Jasper St. Pierre
jstpierre at mecheye.net
Mon Nov 24 22:38:43 CET 2014
This still crashes for me:
kernel: ------------[ cut here ]------------
kernel: WARNING: at drivers/gpu/drm/drm_modeset_lock.c:219
drm_modeset_legacy_acquire_ctx+0x38/0x40()
kernel: Modules linked in:
kernel: CPU: 0 PID: 586 Comm: Xorg Not tainted 3.10.33-02454-g1c4eeb3-dirty
#196
kernel: [<c0014c9c>] (unwind_backtrace+0x0/0xec) from [<c0011d34>]
(show_stack+0x10/0x14)
kernel: [<c0011d34>] (show_stack+0x10/0x14) from [<c002d2d0>]
(warn_slowpath_common+0x54/0x6c)
kernel: [<c002d2d0>] (warn_slowpath_common+0x54/0x6c) from [<c002d384>]
(warn_slowpath_null+0x1c/0x24)
kernel: [<c002d384>] (warn_slowpath_null+0x1c/0x24) from [<c02ce818>]
(drm_modeset_legacy_acquire_ctx+0x38/0x40)
kernel: [<c02ce818>] (drm_modeset_legacy_acquire_ctx+0x38/0x40) from
[<c02afa9c>] (drm_atomic_helper_disable_plane+0x24/0xd0)
kernel: [<c02afa9c>] (drm_atomic_helper_disable_plane+0x24/0xd0) from
[<c02c19a4>] (__setplane_internal+0x28/0x2cc)
kernel: [<c02c19a4>] (__setplane_internal+0x28/0x2cc) from [<c02c287c>]
(drm_mode_cursor_common+0x1cc/0x2f8)
kernel: [<c02c287c>] (drm_mode_cursor_common+0x1cc/0x2f8) from [<c02c53d4>]
(drm_mode_cursor_ioctl+0x58/0x60)
kernel: [<c02c53d4>] (drm_mode_cursor_ioctl+0x58/0x60) from [<c02b917c>]
(drm_ioctl+0x318/0x510)
kernel: [<c02b917c>] (drm_ioctl+0x318/0x510) from [<c00e2d9c>]
(do_vfs_ioctl+0x55c/0x5b0)
kernel: [<c00e2d9c>] (do_vfs_ioctl+0x55c/0x5b0) from [<c00e2e40>]
(SyS_ioctl+0x50/0x7c)
kernel: [<c00e2e40>] (SyS_ioctl+0x50/0x7c) from [<c000e000>]
(ret_fast_syscall+0x0/0x30)
This seems to try to acquire the global device lock as instantiated by
drm_modeset_lock_all, but nothing in this path calls that. I'm not sure
what lock we can acquire when we don't have a CRTC.
On Fri, Nov 21, 2014 at 8:55 AM, Daniel Vetter <daniel.vetter at ffwll.ch>
wrote:
> I've missed checking this and so didn't notice that there's a NULL
> check missing. Since depending upon calling context the crtc might not
> even be there (disable-me-harder does happen around planes, especially
> in cleanup code) we need to dodge the oops and look at the global
> acquire ctx.
>
> v2: Actually fix the oops for real and don't just move it two lines
> down. That requires that we pass a drm_device pointer for the cases
> where crtc could be NULL.
>
> Reported-by: "Jasper St. Pierre" <jstpierre at mecheye.net>
> Cc: "Jasper St. Pierre" <jstpierre at mecheye.net>
> Cc: Rob Clark <robdclark at gmail.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
> drivers/gpu/drm/drm_atomic_helper.c | 12 ++++++++----
> drivers/gpu/drm/drm_modeset_lock.c | 12 ++++++++----
> include/drm/drm_modeset_lock.h | 3 ++-
> 3 files changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> b/drivers/gpu/drm/drm_atomic_helper.c
> index ca839bd9bb0d..32c34b5d5f68 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -1171,7 +1171,8 @@ int drm_atomic_helper_update_plane(struct drm_plane
> *plane,
> if (!state)
> return -ENOMEM;
>
> - state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
> + state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc,
> + plane->dev);
> retry:
> plane_state = drm_atomic_get_plane_state(state, plane);
> if (IS_ERR(plane_state)) {
> @@ -1239,7 +1240,8 @@ int drm_atomic_helper_disable_plane(struct drm_plane
> *plane)
> if (!state)
> return -ENOMEM;
>
> - state->acquire_ctx = drm_modeset_legacy_acquire_ctx(plane->crtc);
> + state->acquire_ctx = drm_modeset_legacy_acquire_ctx(plane->crtc,
> + plane->dev);
> retry:
> plane_state = drm_atomic_get_plane_state(state, plane);
> if (IS_ERR(plane_state)) {
> @@ -1391,7 +1393,8 @@ int drm_atomic_helper_set_config(struct drm_mode_set
> *set)
> if (!state)
> return -ENOMEM;
>
> - state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
> + state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc,
> + crtc->dev);
> retry:
> crtc_state = drm_atomic_get_crtc_state(state, crtc);
> if (IS_ERR(crtc_state)) {
> @@ -1676,7 +1679,8 @@ int drm_atomic_helper_page_flip(struct drm_crtc
> *crtc,
> if (!state)
> return -ENOMEM;
>
> - state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
> + state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc,
> + crtc->dev);
> retry:
> crtc_state = drm_atomic_get_crtc_state(state, crtc);
> if (IS_ERR(crtc_state)) {
> diff --git a/drivers/gpu/drm/drm_modeset_lock.c
> b/drivers/gpu/drm/drm_modeset_lock.c
> index 474e4d12a2d8..655958d4f23e 100644
> --- a/drivers/gpu/drm/drm_modeset_lock.c
> +++ b/drivers/gpu/drm/drm_modeset_lock.c
> @@ -200,21 +200,25 @@ EXPORT_SYMBOL(drm_modeset_lock_crtc);
> /**
> * drm_modeset_legacy_acquire_ctx - find acquire ctx for legacy ioctls
> * @crtc: drm crtc
> + * @dev: device
> *
> * Legacy ioctl operations like cursor updates or page flips only have
> per-crtc
> * locking, and store the acquire ctx in the corresponding crtc. All other
> * legacy operations take all locks and use a global acquire context. This
> * function grabs the right one.
> + *
> + * Note that either @crtc or @dev can be NULL, but not both.
> */
> struct drm_modeset_acquire_ctx *
> -drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc)
> +drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc,
> + struct drm_device *dev)
> {
> - if (crtc->acquire_ctx)
> + if (crtc && crtc->acquire_ctx)
> return crtc->acquire_ctx;
>
> - WARN_ON(!crtc->dev->mode_config.acquire_ctx);
> + WARN_ON(!dev->mode_config.acquire_ctx);
>
> - return crtc->dev->mode_config.acquire_ctx;
> + return dev->mode_config.acquire_ctx;
> }
> EXPORT_SYMBOL(drm_modeset_legacy_acquire_ctx);
>
> diff --git a/include/drm/drm_modeset_lock.h
> b/include/drm/drm_modeset_lock.h
> index 28931a23d96c..cdbfd822e52f 100644
> --- a/include/drm/drm_modeset_lock.h
> +++ b/include/drm/drm_modeset_lock.h
> @@ -135,7 +135,8 @@ void drm_modeset_lock_crtc(struct drm_crtc *crtc);
> void drm_modeset_unlock_crtc(struct drm_crtc *crtc);
> void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
> struct drm_modeset_acquire_ctx *
> -drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc);
> +drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc,
> + struct drm_device *dev);
>
> int drm_modeset_lock_all_crtcs(struct drm_device *dev,
> struct drm_modeset_acquire_ctx *ctx);
> --
> 2.1.1
>
>
--
Jasper
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