[PATCH v2] video: fbdev: uvesafb.c: Added additional error checking

Variable was assigned a value that is never used.
Now the variable is used, and the function returns if a call to
uvesafb_exec() returns a error.

Signed-off-by: Rickard Strandqvist <redacted>
---
 drivers/video/fbdev/uvesafb.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/video/fbdev/uvesafb.c b/drivers/video/fbdev/uvesafb.c
index 509d452..47c2d74 100644
--- a/drivers/video/fbdev/uvesafb.c
+++ b/drivers/video/fbdev/uvesafb.c

@@ -561,6 +561,8 @@ static int uvesafb_vbe_getpmi(struct uvesafb_ktask *task,
 	task->t.regs.eax = 0x4f0a;
 	task->t.regs.ebx = 0x0;
 	err = uvesafb_exec(task);
+	if (err)
+		return err;
 
 	if ((task->t.regs.eax & 0xffff) != 0x4f || task->t.regs.es < 0xc000) {
 		par->pmi_setpal = par->ypan = 0;

-- 
1.7.10.4

On Wed, Jul 23, 2014 at 11:20:27PM +0200, Rickard Strandqvist wrote:

Variable was assigned a value that is never used.
Now the variable is used, and the function returns if a call to
uvesafb_exec() returns a error.

Because the only user of uvesafb_vbe_getpmi in uvesafb.c
don't check its return value, it should do the check indeed,
so maybe below change is better:

-       if ((task->t.regs.eax & 0xffff) != 0x4f || task->t.regs.es < 0xc000) {
+       if (err || (task->t.regs.eax & 0xffff) != 0x4f || task->t.regs.es < 0xc000) {
                par->pmi_setpal = par->ypan = 0;
        }

Or we check uvesafb_vbe_getpmi's return value, then the code will looks like below:

if (uvesafb_vbe_getpmi(task, par))
    par->pmi_setpal = par->ypan = 0;


Thanks.

On Wed, Jul 23, 2014 at 11:20:27PM +0200, Rickard Strandqvist wrote:

Variable was assigned a value that is never used.
Now the variable is used, and the function returns if a call to
uvesafb_exec() returns a error.

Because the only user of uvesafb_vbe_getpmi in uvesafb.c
don't check its return value, it should do the check indeed,
so maybe below change is better:

-       if ((task->t.regs.eax & 0xffff) != 0x4f || task->t.regs.es < 0xc000) {
+       if (err || (task->t.regs.eax & 0xffff) != 0x4f || task->t.regs.es < 0xc000) {
                par->pmi_setpal = par->ypan = 0;
        }

Or we check uvesafb_vbe_getpmi's return value, then the code will looks like below:

if (uvesafb_vbe_getpmi(task, par))
    par->pmi_setpal = par->ypan = 0;


Add cc:pavel@ucw.cz, you should cc all the people who replied your patch 
in later patch version.

Thanks.

2014-07-24 19:36 GMT+02:00 Wang YanQing [off-list ref]:

On Wed, Jul 23, 2014 at 11:20:27PM +0200, Rickard Strandqvist wrote:

quoted

Variable was assigned a value that is never used.
Now the variable is used, and the function returns if a call to
uvesafb_exec() returns a error.

Because the only user of uvesafb_vbe_getpmi in uvesafb.c
don't check its return value, it should do the check indeed,
so maybe below change is better:

-       if ((task->t.regs.eax & 0xffff) != 0x4f || task->t.regs.es < 0xc000) {
+       if (err || (task->t.regs.eax & 0xffff) != 0x4f || task->t.regs.es < 0xc000) {
                par->pmi_setpal = par->ypan = 0;
        }

Or we check uvesafb_vbe_getpmi's return value, then the code will looks like below:

if (uvesafb_vbe_getpmi(task, par))
    par->pmi_setpal = par->ypan = 0;

Hi

Sure, I saw that much of the other code using something like:
if (err || ...)


But this whole discussion start with that you wished it would return
the error, and then error code I assumed?

Ok, but something like this then?

err = uvesafb_exec(task);
if (err) {
  par->pmi_setpal = par->ypan = 0;
  return err;
}


Kind regards
Rickard Strandqvist