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Subject[PATCH 3.8 42/81] cpufreq: powernow-k8: Initialize per-cpu data-structures properly
Date
3.8.13.20 -stable review patch.  If anyone has any objections, please let me know.

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

From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.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@ossman.eu>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
drivers/cpufreq/powernow-k8.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 056faf6..69bf037 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -1102,7 +1102,7 @@ static int __cpuinit powernowk8_cpu_init(struct cpufreq_policy *pol)
{
struct powernow_k8_data *data;
struct init_on_cpu init_on_cpu;
- int rc;
+ int rc, cpu;

if (!cpu_online(pol->cpu))
return -ENODEV;
@@ -1174,7 +1174,9 @@ static int __cpuinit 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;

@@ -1189,6 +1191,7 @@ 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;
@@ -1199,7 +1202,8 @@ 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;
}
--
1.8.3.2


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