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>

diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index e10b646..6684e03 100644 (file)
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -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;
 }