Re: [PATCH] video: fbdev: Convert timers to use timer_setup()

On Thu, Nov 9, 2017 at 9:08 AM, Bartlomiej Zolnierkiewicz
[off-list ref] wrote:

On Tuesday, October 24, 2017 08:20:26 AM Kees Cook wrote:

quoted

diff --git a/drivers/video/fbdev/pxa3xx-gcu.c b/drivers/video/fbdev/pxa3xx-gcu.c
index 933619da1a94..e88447eac32c 100644
--- a/drivers/video/fbdev/pxa3xx-gcu.c
+++ b/drivers/video/fbdev/pxa3xx-gcu.c

@@ -513,16 +513,10 @@ pxa3xx_gcu_mmap(struct file *file, struct vm_area_struct *vma)
 #ifdef PXA3XX_GCU_DEBUG_TIMER
 static struct timer_list pxa3xx_gcu_debug_timer;

-static void pxa3xx_gcu_debug_timedout(unsigned long ptr)
+static void pxa3xx_gcu_debug_timedout(struct timer_list *unused)
 {
-     struct pxa3xx_gcu_priv *priv = (struct pxa3xx_gcu_priv *) ptr;
-
      QERROR("Timer DUMP");

QERROR() macro is using priv so this code now fails to build.

Ah, yes, I see. However, in looking at this, I don't think it ever
worked. The existing code does:

static void pxa3xx_gcu_init_debug_timer(void)
{
        pxa3xx_gcu_debug_timedout((unsigned long) &pxa3xx_gcu_debug_timer);
}
...
static void pxa3xx_gcu_debug_timedout(unsigned long ptr)
{
        struct pxa3xx_gcu_priv *priv = (struct pxa3xx_gcu_priv *) ptr;

        QERROR("Timer DUMP");
...

But pxa3xx_gcu_debug_timer is not a struct pxa3xx_gcu_priv, so
QERROR() will be reporting garbage.

I will send a patch that fixes this and switches to timer_setup(),
though it might make more sense to just remove the debug timer
entirely.

[ Please compile these timer changes with PXA3XX_GCU_DEBUG and
  PXA3XX_GCU_DEBUG_TIMER defined. ]

Hm, these appear to be manual knobs? What do you think about wiring
these up to a Kconfig so build tests for things like "make
allmodconfig" would enable it? This would allow for much greater build
coverage.

Also please port your changes over fbdvev-for-next tree as
currently this patch doesn't apply (fbdev tree contains
"video: fbdev: pxa3xx_gcu: Use setup_timer and mod_timer"
cleanup).

Sure thing, thanks!

-Kees

-- 
Kees Cook
Pixel Security