[QUANTAL,1/1] fbcon: fix locking harder

From: Dave Airlie <airlied@gmail.com>

BugLink: http://bugs.launchpad.net/bugs/1167114

Okay so Alan's patch handled the case where there was no registered fbcon,
however the other path entered in set_con2fb_map pit.

In there we called fbcon_takeover, but we also took the console lock in a couple
of places. So push the console lock out to the callers of set_con2fb_map,

this means fbmem and switcheroo needed to take the lock around the fb notifier
entry points that lead to this.

This should fix the efifb regression seen by Maarten.

Tested-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Tested-by: Lu Hua <huax.lu@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Brad Figg <brad.figg@canonical.com>
---
 drivers/gpu/vga/vga_switcheroo.c |  3 +++
 drivers/video/console/fbcon.c    | 11 ++++++++---
 drivers/video/fbmem.c            |  2 ++
 3 files changed, 13 insertions(+), 3 deletions(-)

On Tue, 2013-04-23 at 13:01 -0700, Brad Figg wrote:
> From: Dave Airlie <airlied@gmail.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1167114
> 
> Okay so Alan's patch handled the case where there was no registered fbcon,
> however the other path entered in set_con2fb_map pit.
> 
> In there we called fbcon_takeover, but we also took the console lock in a couple
> of places. So push the console lock out to the callers of set_con2fb_map,
> 
> this means fbmem and switcheroo needed to take the lock around the fb notifier
> entry points that lead to this.
> 
> This should fix the efifb regression seen by Maarten.
> 
> Tested-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
> Tested-by: Lu Hua <huax.lu@intel.com>
> Signed-off-by: Dave Airlie <airlied@redhat.com>
> Signed-off-by: Brad Figg <brad.figg@canonical.com>
> ---
>  drivers/gpu/vga/vga_switcheroo.c |  3 +++
>  drivers/video/console/fbcon.c    | 11 ++++++++---
>  drivers/video/fbmem.c            |  2 ++
>  3 files changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
> index e25cf31..f5282e4 100644
> --- a/drivers/gpu/vga/vga_switcheroo.c
> +++ b/drivers/gpu/vga/vga_switcheroo.c
> @@ -26,6 +26,7 @@
>  #include <linux/fb.h>
>  
>  #include <linux/pci.h>
> +#include <linux/console.h>
>  #include <linux/vga_switcheroo.h>
>  
>  #include <linux/vgaarb.h>
> @@ -338,8 +339,10 @@ static int vga_switchto_stage2(struct vga_switcheroo_client *new_client)
>  
>  	if (new_client->fb_info) {
>  		struct fb_event event;
> +		console_lock();
>  		event.info = new_client->fb_info;
>  		fb_notifier_call_chain(FB_EVENT_REMAP_ALL_CONSOLE, &event);
> +		console_unlock();
>  	}
>  
>  	ret = vgasr_priv.handler->switchto(new_client->id);
> diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
> index 5bf163e..18ded2d 100644
> --- a/drivers/video/console/fbcon.c
> +++ b/drivers/video/console/fbcon.c
> @@ -842,6 +842,8 @@ static void con2fb_init_display(struct vc_data *vc, struct fb_info *info,
>   *
>   *	Maps a virtual console @unit to a frame buffer device
>   *	@newidx.
> + *
> + *	This should be called with the console lock held.
>   */
>  static int set_con2fb_map(int unit, int newidx, int user)
>  {
> @@ -859,7 +861,7 @@ static int set_con2fb_map(int unit, int newidx, int user)
>  
>  	if (!search_for_mapped_con() || !con_is_bound(&fb_con)) {
>  		info_idx = newidx;
> -		return fbcon_takeover(0);
> +		return do_fbcon_takeover(0);
>  	}
>  
>  	if (oldidx != -1)
> @@ -867,7 +869,6 @@ static int set_con2fb_map(int unit, int newidx, int user)
>  
>  	found = search_fb_in_map(newidx);
>  
> -	console_lock();
>  	con2fb_map[unit] = newidx;
>  	if (!err && !found)
>   		err = con2fb_acquire_newinfo(vc, info, unit, oldidx);
> @@ -894,7 +895,6 @@ static int set_con2fb_map(int unit, int newidx, int user)
>  	if (!search_fb_in_map(info_idx))
>  		info_idx = newidx;
>  
> -	console_unlock();
>   	return err;
>  }
>  
> @@ -3025,6 +3025,7 @@ static inline int fbcon_unbind(void)
>  }
>  #endif /* CONFIG_VT_HW_CONSOLE_BINDING */
>  
> +/* called with console_lock held */
>  static int fbcon_fb_unbind(int idx)
>  {
>  	int i, new_idx = -1, ret = 0;
> @@ -3051,6 +3052,7 @@ static int fbcon_fb_unbind(int idx)
>  	return ret;
>  }
>  
> +/* called with console_lock held */
>  static int fbcon_fb_unregistered(struct fb_info *info)
>  {
>  	int i, idx;
> @@ -3088,6 +3090,7 @@ static int fbcon_fb_unregistered(struct fb_info *info)
>  	return 0;
>  }
>  
> +/* called with console_lock held */
>  static void fbcon_remap_all(int idx)
>  {
>  	int i;
> @@ -3132,6 +3135,7 @@ static inline void fbcon_select_primary(struct fb_info *info)
>  }
>  #endif /* CONFIG_FRAMEBUFFER_DETECT_PRIMARY */
>  
> +/* called with console_lock held */
>  static int fbcon_fb_registered(struct fb_info *info)
>  {
>  	int ret = 0, i, idx;
> @@ -3284,6 +3288,7 @@ static int fbcon_event_notify(struct notifier_block *self,
>  		ret = fbcon_fb_unregistered(info);
>  		break;
>  	case FB_EVENT_SET_CONSOLE_MAP:
> +		/* called with console lock held */
>  		con2fb = event->data;
>  		ret = set_con2fb_map(con2fb->console - 1,
>  				     con2fb->framebuffer, 1);
> diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
> index afa804f..e4cc585 100644
> --- a/drivers/video/fbmem.c
> +++ b/drivers/video/fbmem.c
> @@ -1177,8 +1177,10 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
>  		event.data = &con2fb;
>  		if (!lock_fb_info(info))
>  			return -ENODEV;
> +		console_lock();
>  		event.info = info;
>  		ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, &event);
> +		console_unlock();
>  		unlock_fb_info(info);
>  		break;
>  	case FBIOBLANK:
> -- 
> 1.8.1.2
> 
> 

Code looks reasonable.

 -Kamal

On 04/23/2013 01:01 PM, Brad Figg wrote:
> From: Dave Airlie <airlied@gmail.com>
>
> BugLink: http://bugs.launchpad.net/bugs/1167114
>
> Okay so Alan's patch handled the case where there was no registered fbcon,
> however the other path entered in set_con2fb_map pit.
>
> In there we called fbcon_takeover, but we also took the console lock in a couple
> of places. So push the console lock out to the callers of set_con2fb_map,
>
> this means fbmem and switcheroo needed to take the lock around the fb notifier
> entry points that lead to this.
>
> This should fix the efifb regression seen by Maarten.
>
> Tested-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
> Tested-by: Lu Hua <huax.lu@intel.com>
> Signed-off-by: Dave Airlie <airlied@redhat.com>
> Signed-off-by: Brad Figg <brad.figg@canonical.com>

Picked from upstream.  This has been well tested to confirm it resolves
a widespread regression.  Be sure to shove in the upstream commit sha1
for reference when you push.

Acked-by: Leann Ogasawara <leann.ogasawara@canonical.com>

> ---
>  drivers/gpu/vga/vga_switcheroo.c |  3 +++
>  drivers/video/console/fbcon.c    | 11 ++++++++---
>  drivers/video/fbmem.c            |  2 ++
>  3 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
> index e25cf31..f5282e4 100644
> --- a/drivers/gpu/vga/vga_switcheroo.c
> +++ b/drivers/gpu/vga/vga_switcheroo.c
> @@ -26,6 +26,7 @@
>  #include <linux/fb.h>
>  
>  #include <linux/pci.h>
> +#include <linux/console.h>
>  #include <linux/vga_switcheroo.h>
>  
>  #include <linux/vgaarb.h>
> @@ -338,8 +339,10 @@ static int vga_switchto_stage2(struct vga_switcheroo_client *new_client)
>  
>  	if (new_client->fb_info) {
>  		struct fb_event event;
> +		console_lock();
>  		event.info = new_client->fb_info;
>  		fb_notifier_call_chain(FB_EVENT_REMAP_ALL_CONSOLE, &event);
> +		console_unlock();
>  	}
>  
>  	ret = vgasr_priv.handler->switchto(new_client->id);
> diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
> index 5bf163e..18ded2d 100644
> --- a/drivers/video/console/fbcon.c
> +++ b/drivers/video/console/fbcon.c
> @@ -842,6 +842,8 @@ static void con2fb_init_display(struct vc_data *vc, struct fb_info *info,
>   *
>   *	Maps a virtual console @unit to a frame buffer device
>   *	@newidx.
> + *
> + *	This should be called with the console lock held.
>   */
>  static int set_con2fb_map(int unit, int newidx, int user)
>  {
> @@ -859,7 +861,7 @@ static int set_con2fb_map(int unit, int newidx, int user)
>  
>  	if (!search_for_mapped_con() || !con_is_bound(&fb_con)) {
>  		info_idx = newidx;
> -		return fbcon_takeover(0);
> +		return do_fbcon_takeover(0);
>  	}
>  
>  	if (oldidx != -1)
> @@ -867,7 +869,6 @@ static int set_con2fb_map(int unit, int newidx, int user)
>  
>  	found = search_fb_in_map(newidx);
>  
> -	console_lock();
>  	con2fb_map[unit] = newidx;
>  	if (!err && !found)
>   		err = con2fb_acquire_newinfo(vc, info, unit, oldidx);
> @@ -894,7 +895,6 @@ static int set_con2fb_map(int unit, int newidx, int user)
>  	if (!search_fb_in_map(info_idx))
>  		info_idx = newidx;
>  
> -	console_unlock();
>   	return err;
>  }
>  
> @@ -3025,6 +3025,7 @@ static inline int fbcon_unbind(void)
>  }
>  #endif /* CONFIG_VT_HW_CONSOLE_BINDING */
>  
> +/* called with console_lock held */
>  static int fbcon_fb_unbind(int idx)
>  {
>  	int i, new_idx = -1, ret = 0;
> @@ -3051,6 +3052,7 @@ static int fbcon_fb_unbind(int idx)
>  	return ret;
>  }
>  
> +/* called with console_lock held */
>  static int fbcon_fb_unregistered(struct fb_info *info)
>  {
>  	int i, idx;
> @@ -3088,6 +3090,7 @@ static int fbcon_fb_unregistered(struct fb_info *info)
>  	return 0;
>  }
>  
> +/* called with console_lock held */
>  static void fbcon_remap_all(int idx)
>  {
>  	int i;
> @@ -3132,6 +3135,7 @@ static inline void fbcon_select_primary(struct fb_info *info)
>  }
>  #endif /* CONFIG_FRAMEBUFFER_DETECT_PRIMARY */
>  
> +/* called with console_lock held */
>  static int fbcon_fb_registered(struct fb_info *info)
>  {
>  	int ret = 0, i, idx;
> @@ -3284,6 +3288,7 @@ static int fbcon_event_notify(struct notifier_block *self,
>  		ret = fbcon_fb_unregistered(info);
>  		break;
>  	case FB_EVENT_SET_CONSOLE_MAP:
> +		/* called with console lock held */
>  		con2fb = event->data;
>  		ret = set_con2fb_map(con2fb->console - 1,
>  				     con2fb->framebuffer, 1);
> diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
> index afa804f..e4cc585 100644
> --- a/drivers/video/fbmem.c
> +++ b/drivers/video/fbmem.c
> @@ -1177,8 +1177,10 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
>  		event.data = &con2fb;
>  		if (!lock_fb_info(info))
>  			return -ENODEV;
> +		console_lock();
>  		event.info = info;
>  		ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, &event);
> +		console_unlock();
>  		unlock_fb_info(info);
>  		break;
>  	case FBIOBLANK: