[PATCH v2] timer-of: handle of_irq_get_byname() result correctly

[Sergei Shtylyov]

of_irq_get_byname() may return a negative error number as well as 0 on
failure, while timer_irq_init() only checks for 0, blithely continuing with
the call to request_[percpu_]irq() -- those functions expect *unsigned int*,
so would probably fail anyway when a large IRQ number resulting from a
conversion of a negative error number is passed to them... This, however,
is incorrect behavior -- error number is not IRQ number.

Filter out the negative error numbers, complain, and return them to the
timer_irq_init()'s callers...

Fixes: dc11bae78529 ("clocksource/drivers: Add timer-of common init routine")
Signed-off-by: Sergei Shtylyov <sergei.shtyl...@cogentembedded.com>

---
The patch is against the 'tip.git' repo's 'timers/core' branch.

Changes in version 2:
- fix the function name in the subject;
- fix the fat-fingered word in the description.

 drivers/clocksource/timer-of.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

Index: tip/drivers/clocksource/timer-of.c
===================================================================
--- tip.orig/drivers/clocksource/timer-of.c
+++ tip/drivers/clocksource/timer-of.c
@@ -41,8 +41,16 @@ static __init int timer_irq_init(struct
        struct timer_of *to = container_of(of_irq, struct timer_of, of_irq);
        struct clock_event_device *clkevt = &to->clkevt;
 
-       of_irq->irq = of_irq->name ? of_irq_get_byname(np, of_irq->name):
-               irq_of_parse_and_map(np, of_irq->index);
+       if (of_irq->name) {
+               of_irq->irq = ret = of_irq_get_byname(np, of_irq->name);
+               if (ret < 0) {
+                       pr_err("Failed to get interrupt %s for %s\n",
+                              of_irq->name, np->full_name);
+                       return ret;
+               }
+       } else  {
+               of_irq->irq = irq_of_parse_and_map(np, of_irq->index);
+       }
        if (!of_irq->irq) {
                pr_err("Failed to map interrupt for %s\n", np->full_name);
                return -EINVAL;