linux-kernel - [PATCH 3.13 110/172] cpufreq: powernow-k8: Initialize per-cpu data-structures properly

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Message-Id: <20140304200303.230401020@linuxfoundation.org>
Date:	Tue,  4 Mar 2014 12:03:14 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Pierre Ossman <pierre@...man.eu>,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 3.13 110/172] cpufreq: powernow-k8: Initialize per-cpu data-structures properly

3.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>

commit c3274763bfc3bf1ececa269ed6e6c4d7ec1c3e5e upstream.

The powernow-k8 driver maintains a per-cpu data-structure called
powernow_data that is used to perform the frequency transitions.
It initializes this data structure only for the policy->cpu. So,
accesses to this data structure by other CPUs results in various
problems because they would have been uninitialized.

Specifically, if a cpu (!= policy->cpu) invokes the drivers' ->get()
function, it returns 0 as the KHz value, since its per-cpu memory
doesn't point to anything valid. This causes problems during
suspend/resume since cpufreq_update_policy() tries to enforce this
(0 KHz) as the current frequency of the CPU, and this madness gets
propagated to adjust_jiffies() as well. Eventually, lots of things
start breaking down, including the r8169 ethernet card, in one
particularly interesting case reported by Pierre Ossman.

Fix this by initializing the per-cpu data-structures of all the CPUs
in the policy appropriately.

References: https://bugzilla.kernel.org/show_bug.cgi?id=70311
Reported-by: Pierre Ossman <pierre@...man.eu>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/cpufreq/powernow-k8.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -1081,7 +1081,7 @@ static int powernowk8_cpu_init(struct cp
 {
 	struct powernow_k8_data *data;
 	struct init_on_cpu init_on_cpu;
-	int rc;
+	int rc, cpu;

 	smp_call_function_single(pol->cpu, check_supported_cpu, &rc, 1);
 	if (rc)
@@ -1145,7 +1145,9 @@ static int powernowk8_cpu_init(struct cp
 	pr_debug("cpu_init done, current fid 0x%x, vid 0x%x\n",
 		 data->currfid, data->currvid);

-	per_cpu(powernow_data, pol->cpu) = data;
+	/* Point all the CPUs in this policy to the same data */
+	for_each_cpu(cpu, pol->cpus)
+		per_cpu(powernow_data, cpu) = data;

 	return 0;

@@ -1160,6 +1162,7 @@ err_out:
 static int powernowk8_cpu_exit(struct cpufreq_policy *pol)
 {
 	struct powernow_k8_data *data = per_cpu(powernow_data, pol->cpu);
+	int cpu;

 	if (!data)
 		return -EINVAL;
@@ -1170,7 +1173,8 @@ static int powernowk8_cpu_exit(struct cp

 	kfree(data->powernow_table);
 	kfree(data);
-	per_cpu(powernow_data, pol->cpu) = NULL;
+	for_each_cpu(cpu, pol->cpus)
+		per_cpu(powernow_data, cpu) = NULL;

 	return 0;
 }

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