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; } -- 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/
