Re: linux-next: Crash in arm_pmu_device_probe() due to 'drivers/perf: arm_pmu: make info messages more verbose'

[Dirk Behme]

Hi Guenter,

On 18.03.2016 07:44, Guenter Roeck wrote:
Hi,
I am seeing the attached crash when running a realview-pb-a8 image with
realview_defconfig in qemu.
bisect wasn't successful, but a commit analysis identified commit
'drivers/perf: arm_pmu: make info
messages more verbose' as the culprit. Reverting this commit fixes the
problem.

The code roughly looks as follows.

int arm_pmu_device_probe()
{
     ...
     if (node && ..) {
     } else {
     }

     if (ret) {
                 pr_info("%s: failed to probe PMU! Error %i\n",
                         node->full_name, ret);
                 goto out_free;
     }
     ....
out_free:
     pr_info("%s: failed to register PMU devices! Error %i\n",
                 node->full_name, ret);
     ....
}

Note that 'node' is dereferenced even though it was previously checked
if it is NULL.
The configuration I am testing does not use devicetree.

Can you use dev_info() instead ?


Does anything like below [1] does work for you?

If so, could you please share the output? I.e. what it prints in your 
non-devicetree non-pmu case?

Best regards

Dirk

[1]

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 11bacc7..bda3502 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -1002,8 +1002,7 @@ int arm_pmu_device_probe(struct platform_device *pdev,
        }

        if (ret) {
-               pr_info("%s: failed to probe PMU! Error %i\n",
-                       node->full_name, ret);
+               dev_info(&pdev->dev, "failed to probe PMU! Error %i\n", 
ret);
                goto out_free;
        }

@@ -1023,8 +1022,7 @@ int arm_pmu_device_probe(struct platform_device *pdev,
 out_destroy:
        cpu_pmu_destroy(pmu);
 out_free:
-       pr_info("%s: failed to register PMU devices! Error %i\n",
-               node->full_name, ret);
+       dev_info(&pdev->dev, "failed to register PMU devices! Error 
%i\n", ret);
        kfree(pmu);
        return ret;
 }