unblank_screen() can be called from interrupt context during oops. thus all ->fb_blank handlers should avoid sleeping in this situation.
callstack: panic() bust_spinlocks(1) unblank_screen() vc->vc_sw->con_blank() fbcon_blank() fb_blank() info->fbops->fb_blank() drm_fb_helper_blank() drm_fb_helper_dpms() mutex_lock(&dev->mode_config.mutex)
Signed-off-by: Konstantin Khlebnikov khlebnikov@openvz.org Cc: Andrew Morton akpm@linux-foundation.org Cc: David Airlie airlied@linux.ie Cc: dri-devel@lists.freedesktop.org --- drivers/gpu/drm/drm_fb_helper.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 954d175..2c9f49f 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -326,7 +326,7 @@ static struct sysrq_key_op sysrq_drm_fb_helper_restore_op = { static struct sysrq_key_op sysrq_drm_fb_helper_restore_op = { }; #endif
-static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode) +static int drm_fb_helper_dpms(struct fb_info *info, int dpms_mode) { struct drm_fb_helper *fb_helper = info->par; struct drm_device *dev = fb_helper->dev; @@ -334,10 +334,15 @@ static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode) struct drm_connector *connector; int i, j;
+ if (oops_in_progress) { + if (!mutex_trylock(&dev->mode_config.mutex)) + return -EBUSY; + } else + mutex_lock(&dev->mode_config.mutex); + /* * For each CRTC in this fb, turn the connectors on/off. */ - mutex_lock(&dev->mode_config.mutex); for (i = 0; i < fb_helper->crtc_count; i++) { crtc = fb_helper->crtc_info[i].mode_set.crtc;
@@ -353,6 +358,7 @@ static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode) } } mutex_unlock(&dev->mode_config.mutex); + return 0; }
int drm_fb_helper_blank(int blank, struct fb_info *info) @@ -360,24 +366,19 @@ int drm_fb_helper_blank(int blank, struct fb_info *info) switch (blank) { /* Display: On; HSync: On, VSync: On */ case FB_BLANK_UNBLANK: - drm_fb_helper_dpms(info, DRM_MODE_DPMS_ON); - break; + return drm_fb_helper_dpms(info, DRM_MODE_DPMS_ON); /* Display: Off; HSync: On, VSync: On */ case FB_BLANK_NORMAL: - drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY); - break; + return drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY); /* Display: Off; HSync: Off, VSync: On */ case FB_BLANK_HSYNC_SUSPEND: - drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY); - break; + return drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY); /* Display: Off; HSync: On, VSync: Off */ case FB_BLANK_VSYNC_SUSPEND: - drm_fb_helper_dpms(info, DRM_MODE_DPMS_SUSPEND); - break; + return drm_fb_helper_dpms(info, DRM_MODE_DPMS_SUSPEND); /* Display: Off; HSync: Off, VSync: Off */ case FB_BLANK_POWERDOWN: - drm_fb_helper_dpms(info, DRM_MODE_DPMS_OFF); - break; + return drm_fb_helper_dpms(info, DRM_MODE_DPMS_OFF); } return 0; }