Bugzilla: 1054408
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From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Subject: [PATCH] cpufreq,
powernow-k8: Initialize per-cpu data-structures properly
To: pierre-list@ossman.eu, rjw@rjwysocki.net
Cc: viresh.kumar@linaro.org, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org,
"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Date: Mon, 17 Feb 2014 16:18:21 +0530
Message-ID: <20140217104821.21147.71463.stgit@srivatsabhat.in.ibm.com>
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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;
}
--
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