[PATCH] cpufreq: powernv: Fix frame-size-overflow in powernv_cpufreq_reboot_notifier

The patch avoids allocating cpufreq_policy on stack hence fixing frame
size overflow in 'powernv_cpufreq_reboot_notifier'

./drivers/cpufreq/powernv-cpufreq.c: In function _powernv_cpufreq_reboot_notifier_:
./drivers/cpufreq/powernv-cpufreq.c:906:1: error: the frame size of 2064 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
 }
 ^
cc1: all warnings being treated as errors
make[3]: *** [./scripts/Makefile.build:316: drivers/cpufreq/powernv-cpufreq.o] Error 1
make[2]: *** [./scripts/Makefile.build:556: drivers/cpufreq] Error 2
make[1]: *** [./Makefile:1072: drivers] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:157: sub-make] Error 2

Fixes: cf30af76 ("cpufreq: powernv: Set the cpus to nominal frequency during reboot/kexec")
Cc: Pratik Rajesh Sampat <redacted>
Cc: Daniel Axtens <redacted>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev <redacted>
Signed-off-by: Srikar Dronamraju <redacted>
---
 drivers/cpufreq/powernv-cpufreq.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index a9af15e..e439b43 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c

@@ -885,12 +885,15 @@ static int powernv_cpufreq_reboot_notifier(struct notifier_block *nb,
 				unsigned long action, void *unused)
 {
 	int cpu;
-	struct cpufreq_policy cpu_policy;
+	struct cpufreq_policy *cpu_policy;
 
 	rebooting = true;
 	for_each_online_cpu(cpu) {
-		cpufreq_get_policy(&cpu_policy, cpu);
-		powernv_cpufreq_target_index(&cpu_policy, get_nominal_index());
+		cpu_policy = cpufreq_cpu_get(cpu);
+		if (!cpu_policy)
+			continue;
+		powernv_cpufreq_target_index(cpu_policy, get_nominal_index());
+		cpufreq_cpu_put(cpu_policy);
 	}
 
 	return NOTIFY_DONE;

-- 
1.8.3.1

Hi Srikar,

The patch avoids allocating cpufreq_policy on stack hence fixing frame
size overflow in 'powernv_cpufreq_reboot_notifier'

./drivers/cpufreq/powernv-cpufreq.c: In function _powernv_cpufreq_reboot_notifier_:
./drivers/cpufreq/powernv-cpufreq.c:906:1: error: the frame size of 2064 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
 }
 ^
cc1: all warnings being treated as errors
make[3]: *** [./scripts/Makefile.build:316: drivers/cpufreq/powernv-cpufreq.o] Error 1
make[2]: *** [./scripts/Makefile.build:556: drivers/cpufreq] Error 2
make[1]: *** [./Makefile:1072: drivers] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:157: sub-make] Error 2

This looks a lot like commit d95fe371ecd2 ("cpufreq: powernv: Fix frame-size-overflow in powernv_cpufreq_work_fn").

As with that patch, I have checked for matching puts/gets and that all
uses of '&' check out.

I tried to look at the snowpatch tests: they apparently reported a
checkpatch warning but the file has since disappeared so I can't see
what it was. Running checkpatch locally:

$ scripts/checkpatch.pl -g HEAD -strict
WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
#15: 
make[3]: *** [./scripts/Makefile.build:316: drivers/cpufreq/powernv-cpufreq.o] Error 1

This is benign and you shouldn't wrap that line anyway.

On that basis:

Reviewed-by: Daniel Axtens <redacted>

Kind regards,
Daniel

* Daniel Axtens [off-list ref] [2020-09-24 12:35:05]:

Hi Srikar,


This looks a lot like commit d95fe371ecd2 ("cpufreq: powernv: Fix frame-size-overflow in powernv_cpufreq_work_fn").

Yes, very very similar.

As with that patch, I have checked for matching puts/gets and that all
uses of '&' check out.

I tried to look at the snowpatch tests: they apparently reported a
checkpatch warning but the file has since disappeared so I can't see
what it was. Running checkpatch locally:

$ scripts/checkpatch.pl -g HEAD -strict
WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
#15: 
make[3]: *** [./scripts/Makefile.build:316: drivers/cpufreq/powernv-cpufreq.o] Error 1

This is benign and you shouldn't wrap that line anyway.

On that basis:

Reviewed-by: Daniel Axtens <redacted>

Thanks Daniel.

Kind regards,
Daniel

-- 
Thanks and Regards
Srikar Dronamraju

On Tue, 22 Sep 2020 13:32:54 +0530, Srikar Dronamraju wrote:

The patch avoids allocating cpufreq_policy on stack hence fixing frame
size overflow in 'powernv_cpufreq_reboot_notifier'

./drivers/cpufreq/powernv-cpufreq.c: In function _powernv_cpufreq_reboot_notifier_:
./drivers/cpufreq/powernv-cpufreq.c:906:1: error: the frame size of 2064 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
 }
 ^
cc1: all warnings being treated as errors
make[3]: *** [./scripts/Makefile.build:316: drivers/cpufreq/powernv-cpufreq.o] Error 1
make[2]: *** [./scripts/Makefile.build:556: drivers/cpufreq] Error 2
make[1]: *** [./Makefile:1072: drivers] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:157: sub-make] Error 2

Applied to powerpc/next.

[1/1] cpufreq: powernv: Fix frame-size-overflow in powernv_cpufreq_reboot_notifier
      https://git.kernel.org/powerpc/c/a2d0230b91f7e23ceb5d8fb6a9799f30517ec33a

cheers