lkml.org 
[lkml]   [2014]   [Feb]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] cpufreq, powernow-k8: Initialize per-cpu data-structures properly
Date
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.

https://bugzilla.kernel.org/show_bug.cgi?id=70311

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

Cc: stable@vger.kernel.org
Reported-by: Pierre Ossman <pierre@ossman.eu>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.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 e10b646..6684e03 100644
--- 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;
}


\
 
 \ /
  Last update: 2014-02-17 12:41    [W:2.130 / U:0.216 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site