On Monday, February 17, 2014 04:35:08 PM Viresh Kumar wrote: > On 17 February 2014 16:18, Srivatsa S. Bhat > <srivatsa.b...@linux.vnet.ibm.com> wrote: > > 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: sta...@vger.kernel.org > > Reported-by: Pierre Ossman <pie...@ossman.eu> > > Signed-off-by: Srivatsa S. Bhat <srivatsa.b...@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; > > Acked-by: Viresh Kumar <viresh.ku...@linaro.org>
Queued up as a fix for 3.14, thanks! -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
