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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>
This commit is contained in:
Srivatsa S. Bhat 2014-02-17 16:18:21 +05:30 committed by Rafael J. Wysocki
parent 6964d91db2
commit c3274763bf
1 changed files with 7 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/cpufreq/powernow-k8.c
View File

@ -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 @@ static int powernowk8_cpu_init(struct cpufreq_policy *pol)
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;
}