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Message-ID: <20121214110100.7836.65250.stgit@zurg>
Date: Fri, 14 Dec 2012 15:01:00 +0400
From: Konstantin Khlebnikov <khlebnikov@...nvz.org>
To: linux-kernel@...r.kernel.org
Cc: David Airlie <airlied@...ux.ie>,
Andrew Morton <akpm@...ux-foundation.org>,
dri-devel@...ts.freedesktop.org
Subject: [PATCH] drm/fb: avoid sleeping in unblank_screen() if oops in progress
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@...nvz.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: David Airlie <airlied@...ux.ie>
Cc: dri-devel@...ts.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;
}
--
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