thermal: rcar: Fix race condition between init and interrupt

As soon as the interrupt has been enabled by devm_request_irq(), the
interrupt routine may be called, depending on the current status of the
hardware.

However, at that point rcar_thermal_common hasn't been initialized
complely yet. E.g. rcar_thermal_common.base is still NULL, causing a
NULL pointer dereference:

    Unable to handle kernel NULL pointer dereference at virtual address 0000000c
    pgd = c0004000
    [0000000c] *pgd=00000000
    Internal error: Oops: 5 [#1] SMP ARM
    CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.19.0-rc7-ape6evm-04564-gb6e46cb7cbe82389 #30
    Hardware name: Generic R8A73A4 (Flattened Device Tree)
    task: ee8953c0 ti: ee896000 task.ti: ee896000
    PC is at rcar_thermal_irq+0x1c/0xf0
    LR is at _raw_spin_lock_irqsave+0x48/0x54

Postpone the call to devm_request_irq() until all initialization has
been done to fix this.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

1 files changed, 9 insertions, 13 deletions

diff --git a/drivers/thermal/rcar_thermal.c b/drivers/thermal/rcar_thermal.c
index 2580a4872f90..3c2c1720ba4a 100644
--- a/drivers/thermal/rcar_thermal.c
+++ b/drivers/thermal/rcar_thermal.c
@@ -387,21 +387,9 @@ static int rcar_thermal_probe(struct platform_device *pdev)
 
         irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
         if (irq) {
-                int ret;
-
                 /*
                  * platform has IRQ support.
                  * Then, driver uses common registers
-                 */
-
-                ret = devm_request_irq(dev, irq->start, rcar_thermal_irq, 0,
-                                       dev_name(dev), common);
-                if (ret) {
-                        dev_err(dev, "irq request failed\n ");
-                        return ret;
-                }
-
-                /*
                  * rcar_has_irq_support() will be enabled
                  */
                 res = platform_get_resource(pdev, IORESOURCE_MEM, mres++);
@@ -456,8 +444,16 @@ static int rcar_thermal_probe(struct platform_device *pdev)
         }
 
         /* enable temperature comparation */
-        if (irq)
+        if (irq) {
+                ret = devm_request_irq(dev, irq->start, rcar_thermal_irq, 0,
+                                       dev_name(dev), common);
+                if (ret) {
+                        dev_err(dev, "irq request failed\n ");
+                        goto error_unregister;
+                }
+
                 rcar_thermal_common_write(common, ENR, enr_bits);
+        }
 
         platform_set_drvdata(pdev, common);