[PATCH 1/1] platform/x86/intel/ifs: release cpus_read_lock()

[PATCH 1/1] platform/x86/intel/ifs: release cpus_read_lock()

[Jithu Joseph]

Couple of error paths in do_core_test() was returning directly without
doing a necessary cpus_read_unlock().

Following lockdep warning was observed when exercising these scenarios
with PROVE_RAW_LOCK_NESTING enabled:

[  139.304775] ================================================
[  139.311185] WARNING: lock held when returning to user space!
[  139.317593] 6.6.0-rc2ifs01+ #11 Tainted: G S      W I
[  139.324499] ------------------------------------------------
[  139.330908] bash/11476 is leaving the kernel with locks still held!
[  139.338000] 1 lock held by bash/11476:
[  139.342262]  #0: ffffffffaa26c930 (cpu_hotplug_lock){++++}-{0:0}, at:
do_core_test+0x35/0x1c0 [intel_ifs]

Fix the flow so that all scenarios release the lock prior to returning
from the function.

Fixes: 5210fb4e1880 ("platform/x86/intel/ifs: Sysfs interface for Array BIST")
Cc: stable@vger.kernel.org
Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
---
 drivers/platform/x86/intel/ifs/runtest.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/x86/intel/ifs/runtest.c b/drivers/platform/x86/intel/ifs/runtest.c
index 1061eb7ec399..43c864add778 100644
--- a/drivers/platform/x86/intel/ifs/runtest.c
+++ b/drivers/platform/x86/intel/ifs/runtest.c
@@ -331,14 +331,15 @@ int do_core_test(int cpu, struct device *dev)
 	switch (test->test_num) {
 	case IFS_TYPE_SAF:
 		if (!ifsd->loaded)
-			return -EPERM;
-		ifs_test_core(cpu, dev);
+			ret = -EPERM;
+		else
+			ifs_test_core(cpu, dev);
 		break;
 	case IFS_TYPE_ARRAY_BIST:
 		ifs_array_test_core(cpu, dev);
 		break;
 	default:
-		return -EINVAL;
+		ret = -EINVAL;
 	}
 out:
 	cpus_read_unlock();

base-commit: 6465e260f48790807eef06b583b38ca9789b6072
-- 
2.25.1

Re: [PATCH 1/1] platform/x86/intel/ifs: release cpus_read_lock()

[Hans de Goede]

Hi,

On 9/27/23 20:48, Jithu Joseph wrote:
> Couple of error paths in do_core_test() was returning directly without
> doing a necessary cpus_read_unlock().
> 
> Following lockdep warning was observed when exercising these scenarios
> with PROVE_RAW_LOCK_NESTING enabled:
> 
> [  139.304775] ================================================
> [  139.311185] WARNING: lock held when returning to user space!
> [  139.317593] 6.6.0-rc2ifs01+ #11 Tainted: G S      W I
> [  139.324499] ------------------------------------------------
> [  139.330908] bash/11476 is leaving the kernel with locks still held!
> [  139.338000] 1 lock held by bash/11476:
> [  139.342262]  #0: ffffffffaa26c930 (cpu_hotplug_lock){++++}-{0:0}, at:
> do_core_test+0x35/0x1c0 [intel_ifs]
> 
> Fix the flow so that all scenarios release the lock prior to returning
> from the function.
> 
> Fixes: 5210fb4e1880 ("platform/x86/intel/ifs: Sysfs interface for Array BIST")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>

Thank you for your patch/series, I've applied this patch
(series) to the pdx86 fixes branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=fixes

Note it will show up in the pdx86 fixes branch once I've pushed
my local branch there, which might take a while.

I will include this patch in my next fixes pull-req to Linus
for the current kernel development cycle.

Regards,

Hans





> ---
>  drivers/platform/x86/intel/ifs/runtest.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/platform/x86/intel/ifs/runtest.c b/drivers/platform/x86/intel/ifs/runtest.c
> index 1061eb7ec399..43c864add778 100644
> --- a/drivers/platform/x86/intel/ifs/runtest.c
> +++ b/drivers/platform/x86/intel/ifs/runtest.c
> @@ -331,14 +331,15 @@ int do_core_test(int cpu, struct device *dev)
>  	switch (test->test_num) {
>  	case IFS_TYPE_SAF:
>  		if (!ifsd->loaded)
> -			return -EPERM;
> -		ifs_test_core(cpu, dev);
> +			ret = -EPERM;
> +		else
> +			ifs_test_core(cpu, dev);
>  		break;
>  	case IFS_TYPE_ARRAY_BIST:
>  		ifs_array_test_core(cpu, dev);
>  		break;
>  	default:
> -		return -EINVAL;
> +		ret = -EINVAL;
>  	}
>  out:
>  	cpus_read_unlock();
> 
> base-commit: 6465e260f48790807eef06b583b38ca9789b6072