[PATCH v2] staging: sm750fb: always take the lock

From: AbdAllah-MEZITI
Date: Mon Jun 26 2017 - 13:26:41 EST


This patch
- Always take the lock:
The current code only takes the lock if multiple instances are in use.
This is error-prone, and confuses static analyzers.
As taking the lock in case of a single instance is harmless and cheap,
change the code to always take the lock.
- That also fix the sparse warning:
drivers/staging/sm750fb/sm750.c:159:13: warning: context imbalance in 'lynxfb_ops_fillrect' - different lock contexts for basic block
drivers/staging/sm750fb/sm750.c:231:9: warning: context imbalance in 'lynxfb_ops_copyarea' - different lock contexts for basic block
drivers/staging/sm750fb/sm750.c:235:13: warning: context imbalance in 'lynxfb_ops_imageblit' - different lock contexts for basic block

Signed-off-by: AbdAllah MEZITI <abdallah.meziti.pro@xxxxxxxxx>

v2:
- add and fix the changelog text.
---
drivers/staging/sm750fb/sm750.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/staging/sm750fb/sm750.c b/drivers/staging/sm750fb/sm750.c
index 386d4ad..4a22190 100644
--- a/drivers/staging/sm750fb/sm750.c
+++ b/drivers/staging/sm750fb/sm750.c
@@ -186,16 +186,14 @@ static void lynxfb_ops_fillrect(struct fb_info *info,
* If not use spin_lock,system will die if user load driver
* and immediately unload driver frequently (dual)
*/
- if (sm750_dev->fb_count > 1)
- spin_lock(&sm750_dev->slock);
+ spin_lock(&sm750_dev->slock);

sm750_dev->accel.de_fillrect(&sm750_dev->accel,
base, pitch, Bpp,
region->dx, region->dy,
region->width, region->height,
color, rop);
- if (sm750_dev->fb_count > 1)
- spin_unlock(&sm750_dev->slock);
+ spin_unlock(&sm750_dev->slock);
}

static void lynxfb_ops_copyarea(struct fb_info *info,
@@ -220,16 +218,14 @@ static void lynxfb_ops_copyarea(struct fb_info *info,
* If not use spin_lock, system will die if user load driver
* and immediately unload driver frequently (dual)
*/
- if (sm750_dev->fb_count > 1)
- spin_lock(&sm750_dev->slock);
+ spin_lock(&sm750_dev->slock);

sm750_dev->accel.de_copyarea(&sm750_dev->accel,
base, pitch, region->sx, region->sy,
base, pitch, Bpp, region->dx, region->dy,
region->width, region->height,
HW_ROP2_COPY);
- if (sm750_dev->fb_count > 1)
- spin_unlock(&sm750_dev->slock);
+ spin_unlock(&sm750_dev->slock);
}

static void lynxfb_ops_imageblit(struct fb_info *info,
@@ -269,8 +265,7 @@ static void lynxfb_ops_imageblit(struct fb_info *info,
* If not use spin_lock, system will die if user load driver
* and immediately unload driver frequently (dual)
*/
- if (sm750_dev->fb_count > 1)
- spin_lock(&sm750_dev->slock);
+ spin_lock(&sm750_dev->slock);

sm750_dev->accel.de_imageblit(&sm750_dev->accel,
image->data, image->width >> 3, 0,
@@ -278,8 +273,7 @@ static void lynxfb_ops_imageblit(struct fb_info *info,
image->dx, image->dy,
image->width, image->height,
fgcol, bgcol, HW_ROP2_COPY);
- if (sm750_dev->fb_count > 1)
- spin_unlock(&sm750_dev->slock);
+ spin_unlock(&sm750_dev->slock);
}

static int lynxfb_ops_pan_display(struct fb_var_screeninfo *var,
--
2.7.4