clocksource: sh_cmt: Remove nested spinlock fix
Takashi YOSHII [Fri, 17 Dec 2010 07:25:09 +0000 (07:25 +0000)]
There are control flow that sh_cmt_set_next() does double
spin-lock. The callers sh_cmt_{start,stop}() already have
lock. But another callers sh_cmt_clock_event_{start,next}()
does not.

Now sh_cmt_set_next() does not lock by itself. All the
callers should hold spin-lock before calling it.

[damm@opensource.se: use __sh_cmt_set_next() to simplify code]
[damm@opensource.se: added stable, suitable for v2.6.35 + v2.6.36]
Cc: stable@kernel.org
Signed-off-by: Takashi YOSHII <takashi.yoshii.zj@renesas.com>
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

drivers/clocksource/sh_cmt.c

index d68d3aa..f975d24 100644 (file)
@@ -283,16 +283,21 @@ static void sh_cmt_clock_event_program_verify(struct sh_cmt_priv *p,
        } while (delay);
 }
 
-static void sh_cmt_set_next(struct sh_cmt_priv *p, unsigned long delta)
+static void __sh_cmt_set_next(struct sh_cmt_priv *p, unsigned long delta)
 {
-       unsigned long flags;
-
        if (delta > p->max_match_value)
                dev_warn(&p->pdev->dev, "delta out of range\n");
 
-       spin_lock_irqsave(&p->lock, flags);
        p->next_match_value = delta;
        sh_cmt_clock_event_program_verify(p, 0);
+}
+
+static void sh_cmt_set_next(struct sh_cmt_priv *p, unsigned long delta)
+{
+       unsigned long flags;
+
+       spin_lock_irqsave(&p->lock, flags);
+       __sh_cmt_set_next(p, delta);
        spin_unlock_irqrestore(&p->lock, flags);
 }
 
@@ -359,7 +364,7 @@ static int sh_cmt_start(struct sh_cmt_priv *p, unsigned long flag)
 
        /* setup timeout if no clockevent */
        if ((flag == FLAG_CLOCKSOURCE) && (!(p->flags & FLAG_CLOCKEVENT)))
-               sh_cmt_set_next(p, p->max_match_value);
+               __sh_cmt_set_next(p, p->max_match_value);
  out:
        spin_unlock_irqrestore(&p->lock, flags);
 
@@ -381,7 +386,7 @@ static void sh_cmt_stop(struct sh_cmt_priv *p, unsigned long flag)
 
        /* adjust the timeout to maximum if only clocksource left */
        if ((flag == FLAG_CLOCKEVENT) && (p->flags & FLAG_CLOCKSOURCE))
-               sh_cmt_set_next(p, p->max_match_value);
+               __sh_cmt_set_next(p, p->max_match_value);
 
        spin_unlock_irqrestore(&p->lock, flags);
 }