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From: John Hubbard <jhubbard@nvidia.com>
To: Viresh Kumar <viresh.kumar@linaro.org>,
	Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	John Hubbard <jhubbard@nvidia.com>,
	Preeti U Murthy <preeti@linux.vnet.ibm.com>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	<linux-pm@vger.kernel.org>, <linuxppc-dev@lists.ozlabs.org>
Subject: [PATCH v2] cpufreq: powernv: fix stack bloat and NR_CPUS limitation
Date: Thu, 17 Oct 2019 21:55:39 -0700	[thread overview]
Message-ID: <20191018045539.3765565-1-jhubbard@nvidia.com> (raw)

The following build warning occurred on powerpc 64-bit builds:

drivers/cpufreq/powernv-cpufreq.c: In function 'init_chip_info':
drivers/cpufreq/powernv-cpufreq.c:1070:1: warning: the frame size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]

This is due to putting 1024 bytes on the stack:

    unsigned int chip[256];

...and while looking at this, it also has a bug: it fails with a stack
overrun, if CONFIG_NR_CPUS > 256.

Fix both problems by dynamically allocating based on CONFIG_NR_CPUS.

Fixes: 053819e0bf840 ("cpufreq: powernv: Handle throttling due to Pmax capping at chip level")
Cc: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---

Changes since v1: includes Viresh's review commit fixes.

 drivers/cpufreq/powernv-cpufreq.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 6061850e59c9..5b2e968cb5ea 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -1041,9 +1041,14 @@ static struct cpufreq_driver powernv_cpufreq_driver = {
 
 static int init_chip_info(void)
 {
-	unsigned int chip[256];
+	unsigned int *chip;
 	unsigned int cpu, i;
 	unsigned int prev_chip_id = UINT_MAX;
+	int ret = 0;
+
+	chip = kcalloc(CONFIG_NR_CPUS, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
 
 	for_each_possible_cpu(cpu) {
 		unsigned int id = cpu_to_chip_id(cpu);
@@ -1055,8 +1060,10 @@ static int init_chip_info(void)
 	}
 
 	chips = kcalloc(nr_chips, sizeof(struct chip), GFP_KERNEL);
-	if (!chips)
-		return -ENOMEM;
+	if (!chips) {
+		ret = -ENOMEM;
+		goto free_and_return;
+	}
 
 	for (i = 0; i < nr_chips; i++) {
 		chips[i].id = chip[i];
@@ -1066,7 +1073,9 @@ static int init_chip_info(void)
 			per_cpu(chip_info, cpu) =  &chips[i];
 	}
 
-	return 0;
+free_and_return:
+	kfree(chip);
+	return ret;
 }
 
 static inline void clean_chip_info(void)
-- 
2.23.0


WARNING: multiple messages have this Message-ID (diff)
From: John Hubbard <jhubbard@nvidia.com>
To: Viresh Kumar <viresh.kumar@linaro.org>,
	Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Cc: linux-pm@vger.kernel.org, John Hubbard <jhubbard@nvidia.com>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	LKML <linux-kernel@vger.kernel.org>,
	Preeti U Murthy <preeti@linux.vnet.ibm.com>,
	linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v2] cpufreq: powernv: fix stack bloat and NR_CPUS limitation
Date: Thu, 17 Oct 2019 21:55:39 -0700	[thread overview]
Message-ID: <20191018045539.3765565-1-jhubbard@nvidia.com> (raw)

The following build warning occurred on powerpc 64-bit builds:

drivers/cpufreq/powernv-cpufreq.c: In function 'init_chip_info':
drivers/cpufreq/powernv-cpufreq.c:1070:1: warning: the frame size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]

This is due to putting 1024 bytes on the stack:

    unsigned int chip[256];

...and while looking at this, it also has a bug: it fails with a stack
overrun, if CONFIG_NR_CPUS > 256.

Fix both problems by dynamically allocating based on CONFIG_NR_CPUS.

Fixes: 053819e0bf840 ("cpufreq: powernv: Handle throttling due to Pmax capping at chip level")
Cc: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---

Changes since v1: includes Viresh's review commit fixes.

 drivers/cpufreq/powernv-cpufreq.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 6061850e59c9..5b2e968cb5ea 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -1041,9 +1041,14 @@ static struct cpufreq_driver powernv_cpufreq_driver = {
 
 static int init_chip_info(void)
 {
-	unsigned int chip[256];
+	unsigned int *chip;
 	unsigned int cpu, i;
 	unsigned int prev_chip_id = UINT_MAX;
+	int ret = 0;
+
+	chip = kcalloc(CONFIG_NR_CPUS, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
 
 	for_each_possible_cpu(cpu) {
 		unsigned int id = cpu_to_chip_id(cpu);
@@ -1055,8 +1060,10 @@ static int init_chip_info(void)
 	}
 
 	chips = kcalloc(nr_chips, sizeof(struct chip), GFP_KERNEL);
-	if (!chips)
-		return -ENOMEM;
+	if (!chips) {
+		ret = -ENOMEM;
+		goto free_and_return;
+	}
 
 	for (i = 0; i < nr_chips; i++) {
 		chips[i].id = chip[i];
@@ -1066,7 +1073,9 @@ static int init_chip_info(void)
 			per_cpu(chip_info, cpu) =  &chips[i];
 	}
 
-	return 0;
+free_and_return:
+	kfree(chip);
+	return ret;
 }
 
 static inline void clean_chip_info(void)
-- 
2.23.0


             reply	other threads:[~2019-10-18  4:55 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-18  4:55 John Hubbard [this message]
2019-10-18  4:55 ` [PATCH v2] cpufreq: powernv: fix stack bloat and NR_CPUS limitation John Hubbard
2019-10-18  5:07 ` Viresh Kumar
2019-10-18  5:07   ` Viresh Kumar
2019-10-28 15:26   ` Rafael J. Wysocki
2019-10-28 15:26     ` Rafael J. Wysocki
2019-10-31  2:39 ` Michael Ellerman
2019-10-31  5:17   ` John Hubbard
2019-10-31  5:17     ` John Hubbard
2019-11-06  3:35     ` Michael Ellerman
2019-11-06  3:35       ` Michael Ellerman

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