[Xen-devel] [PATCH] Add cpufreq sanity check

["Yu, Ke" <ke.yu@xxxxxxxxx>]

this patch fix the bug 1585 
(http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1585)

root cause: with incorrect BIOS info, cpufreq driver may not start. in this 
case, if user use xenpm to manipulate cpufreq driver, NULL pointer will cause 
xen panic. this patch add the sanity check and warning info to fix this issue.

Signed-off-by: Yu Ke <ke.yu@xxxxxxxxx>

diff -r 92f2ee87e501 xen/drivers/cpufreq/cpufreq.c
--- a/xen/drivers/cpufreq/cpufreq.c     Mon Mar 01 16:50:26 2010 +0000
+++ b/xen/drivers/cpufreq/cpufreq.c     Mon Mar 08 17:14:36 2010 +0800
@@ -177,6 +177,14 @@ int cpufreq_add_cpu(unsigned int cpu)
             processor_pminfo[firstcpu]->perf.domain_info.coord_type) ||
             (perf->domain_info.num_processors !=
             processor_pminfo[firstcpu]->perf.domain_info.num_processors)) {
+
+            printk(KERN_WARNING "cpufreq fail to add CPU%d:"
+                    "incorrect _PSD(%d:%d), expect(%d/%d)\n",
+                    cpu, perf->domain_info.coord_type,
+                    perf->domain_info.num_processors,
+                    processor_pminfo[firstcpu]->perf.domain_info.coord_type,
+                    processor_pminfo[firstcpu]->perf.domain_info.num_processors
+                    );
             return -EINVAL;
         }
     }
@@ -193,6 +201,7 @@ int cpufreq_add_cpu(unsigned int cpu)
         ret = cpufreq_driver->init(policy);
         if (ret) {
             xfree(policy);
+            cpufreq_cpu_policy[cpu] = NULL;
             return ret;
         }
         printk(KERN_EMERG"CPU %u initialization completed\n", cpu);
diff -r 92f2ee87e501 xen/drivers/cpufreq/cpufreq_ondemand.c
--- a/xen/drivers/cpufreq/cpufreq_ondemand.c    Mon Mar 01 16:50:26 2010 +0000
+++ b/xen/drivers/cpufreq/cpufreq_ondemand.c    Mon Mar 08 17:14:36 2010 +0800
@@ -286,6 +286,12 @@ int cpufreq_governor_dbs(struct cpufreq_
         break;
 
     case CPUFREQ_GOV_LIMITS:
+        if ( this_dbs_info->cur_policy == NULL )
+        {
+            printk(KERN_WARNING "CPU%d ondemand governor not started yet,"
+                    "unable to GOV_LIMIT\n", cpu);
+            return -EINVAL;
+        }
         if (policy->max < this_dbs_info->cur_policy->cur)
             __cpufreq_driver_target(this_dbs_info->cur_policy,
                 policy->max, CPUFREQ_RELATION_H);

Attachment: cpufreq_governor_fix.patch
Description: cpufreq_governor_fix.patch

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