[PATCH] staging: sm750fb: fix sparse warning for lock

[Peng Fan]

Use __acquire() and __release() in the right place to silence the sparse
lock checking warning.

drivers/staging/sm750fb/sm750.c:177:13: warning: context imbalance in 'lynxfb_ops_fillrect' - different lock contexts for basic block
drivers/staging/sm750fb/sm750.c:243:9: warning: context imbalance in 'lynxfb_ops_copyarea' - different lock contexts for basic block
drivers/staging/sm750fb/sm750.c:247:13: warning: context imbalance in 'lynxfb_ops_imageblit' - different lock contexts for basic block

Signed-off-by: Peng Fan <van.f...@gmail.com>
Cc: Sudip Mukherjee <sudipm.m...@gmail.com>
Cc: Teddy Wang <teddy...@siliconmotion.com>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/staging/sm750fb/sm750.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/staging/sm750fb/sm750.c b/drivers/staging/sm750fb/sm750.c
index 8e201f1..5ba1c06 100644
--- a/drivers/staging/sm750fb/sm750.c
+++ b/drivers/staging/sm750fb/sm750.c
@@ -203,6 +203,8 @@ static void lynxfb_ops_fillrect(struct fb_info *info,
*/
if (share->dual)
spin_lock(&share->slock);
+ else
+ __acquire(&share->slock);

share->accel.de_fillrect(&share->accel,
base, pitch, Bpp,
@@ -211,6 +213,8 @@ static void lynxfb_ops_fillrect(struct fb_info *info,
color, rop);
if (share->dual)
spin_unlock(&share->slock);
+ else
+ __release(&share->slock);
}

static void lynxfb_ops_copyarea(struct fb_info *info,
@@ -235,6 +239,8 @@ static void lynxfb_ops_copyarea(struct fb_info *info,
*/
if (share->dual)
spin_lock(&share->slock);
+ else
+ __acquire(&share->slock);

share->accel.de_copyarea(&share->accel,
base, pitch, region->sx, region->sy,
@@ -242,6 +248,8 @@ static void lynxfb_ops_copyarea(struct fb_info *info,
region->width, region->height, HW_ROP2_COPY);
if (share->dual)
spin_unlock(&share->slock);
+ else
+ __release(&share->slock);
}

static void lynxfb_ops_imageblit(struct fb_info *info,
@@ -282,6 +290,8 @@ _do_work:
*/
if (share->dual)
spin_lock(&share->slock);
+ else
+ __acquire(&share->slock);

share->accel.de_imageblit(&share->accel,
image->data, image->width>>3, 0,
@@ -291,6 +301,8 @@ _do_work:
fgcol, bgcol, HW_ROP2_COPY);
if (share->dual)
spin_unlock(&share->slock);
+ else
+ __release(&share->slock);
}

static int lynxfb_ops_pan_display(struct fb_var_screeninfo *var,
--
1.8.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majo...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

[Greg KH]

On Wed, Aug 05, 2015 at 09:26:44PM +0800, Peng Fan wrote:
> Use __acquire() and __release() in the right place to silence the sparse
> lock checking warning.
>
> drivers/staging/sm750fb/sm750.c:177:13: warning: context imbalance in 'lynxfb_ops_fillrect' - different lock contexts for basic block
> drivers/staging/sm750fb/sm750.c:243:9: warning: context imbalance in 'lynxfb_ops_copyarea' - different lock contexts for basic block
> drivers/staging/sm750fb/sm750.c:247:13: warning: context imbalance in 'lynxfb_ops_imageblit' - different lock contexts for basic block
>
> Signed-off-by: Peng Fan <van.f...@gmail.com>
> Cc: Sudip Mukherjee <sudipm.m...@gmail.com>
> Cc: Teddy Wang <teddy...@siliconmotion.com>
> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
> ---
> drivers/staging/sm750fb/sm750.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/staging/sm750fb/sm750.c b/drivers/staging/sm750fb/sm750.c
> index 8e201f1..5ba1c06 100644
> --- a/drivers/staging/sm750fb/sm750.c
> +++ b/drivers/staging/sm750fb/sm750.c
> @@ -203,6 +203,8 @@ static void lynxfb_ops_fillrect(struct fb_info *info,
> */
> if (share->dual)
> spin_lock(&share->slock);
> + else
> + __acquire(&share->slock);

That's horrid, please don't do stuff like this just to make a static
checker "quiet".

greg k-h

[Dan Carpenter]

On Wed, Aug 05, 2015 at 09:26:44PM +0800, Peng Fan wrote:

> Use __acquire() and __release() in the right place to silence the sparse
> lock checking warning.
>
> drivers/staging/sm750fb/sm750.c:177:13: warning: context imbalance in 'lynxfb_ops_fillrect' - different lock contexts for basic block
> drivers/staging/sm750fb/sm750.c:243:9: warning: context imbalance in 'lynxfb_ops_copyarea' - different lock contexts for basic block
> drivers/staging/sm750fb/sm750.c:247:13: warning: context imbalance in 'lynxfb_ops_imageblit' - different lock contexts for basic block
>

Sparse is really bad at locking stuff. Smatch is also really bad for
locking and I have been promising to re-write that check for years, but
I take comfort always in the fact that at least it's not as bad as
Sparse.

You should pretty much ignore Sparse locking warnings.

regards,
dan carpenter