Commit c3274763 authored Feb 17, 2014 by Srivatsa S. Bhat Committed by Rafael J. Wysocki Feb 19, 2014

cpufreq: powernow-k8: Initialize per-cpu data-structures properly

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@ossman.eu>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: All applicable <stable@vger.kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

parent 6964d91d

drivers/cpufreq/powernow-k8.c

+7 −3

Original line number	Diff line number	Diff line
		@@ -1076,7 +1076,7 @@ static int powernowk8_cpu_init(struct cpufreq_policy *pol)
		{
		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)
		@@ -1140,7 +1140,9 @@ static int powernowk8_cpu_init(struct cpufreq_policy *pol)
		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;

		@@ -1155,6 +1157,7 @@ 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;
		@@ -1165,7 +1168,8 @@ static int powernowk8_cpu_exit(struct cpufreq_policy *pol)

		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;
		}