acpi_pad: fix error checks

There are some fixes listed below:
1. When met a bogus BIOS, the return value of cpu number maybe is
   a negative value so that acpi_pad_pur get an unexpected result.
2. the return value of function acpi_pad_idle_cpus is useless.
3. enhance the process of create_power_saving_task/destroy_power_saving_task
4. Add more error checks when evaluating _PUR object.
5. one typo fix

Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Acked-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 20 insertions, 17 deletions

diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
index 0d2cdb86158b..a7bd49f0f01f 100644
--- a/drivers/acpi/acpi_pad.c
+++ b/drivers/acpi/acpi_pad.c
@@ -207,7 +207,7 @@ static int power_saving_thread(void *data)
                  * the mechanism only works when all CPUs have RT task running,
                  * as if one CPU hasn't RT task, RT task from other CPUs will
                  * borrow CPU time from this CPU and cause RT task use > 95%
-                 * CPU time. To make 'avoid staration' work, takes a nap here.
+                 * CPU time. To make 'avoid starvation' work, takes a nap here.
                  */
                 if (do_sleep)
                         schedule_timeout_killable(HZ * idle_pct / 100);
@@ -221,14 +221,18 @@ static struct task_struct *ps_tsks[NR_CPUS];
 static unsigned int ps_tsk_num;
 static int create_power_saving_task(void)
 {
+        int rc = -ENOMEM;
+
         ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
                 (void *)(unsigned long)ps_tsk_num,
                 "power_saving/%d", ps_tsk_num);
-        if (ps_tsks[ps_tsk_num]) {
+        rc = IS_ERR(ps_tsks[ps_tsk_num]) ? PTR_ERR(ps_tsks[ps_tsk_num]) : 0;
+        if (!rc)
                 ps_tsk_num++;
-                return 0;
-        }
-        return -EINVAL;
+        else
+                ps_tsks[ps_tsk_num] = NULL;
+
+        return rc;
 }
 
 static void destroy_power_saving_task(void)
@@ -236,6 +240,7 @@ static void destroy_power_saving_task(void)
         if (ps_tsk_num > 0) {
                 ps_tsk_num--;
                 kthread_stop(ps_tsks[ps_tsk_num]);
+                ps_tsks[ps_tsk_num] = NULL;
         }
 }
 
@@ -252,7 +257,7 @@ static void set_power_saving_task_num(unsigned int num)
         }
 }
 
-static int acpi_pad_idle_cpus(unsigned int num_cpus)
+static void acpi_pad_idle_cpus(unsigned int num_cpus)
 {
         get_online_cpus();
 
@@ -260,7 +265,6 @@ static int acpi_pad_idle_cpus(unsigned int num_cpus)
         set_power_saving_task_num(num_cpus);
 
         put_online_cpus();
-        return 0;
 }
 
 static uint32_t acpi_pad_idle_cpus_num(void)
@@ -368,19 +372,21 @@ static void acpi_pad_remove_sysfs(struct acpi_device *device)
 static int acpi_pad_pur(acpi_handle handle, int *num_cpus)
 {
         struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
-        acpi_status status;
         union acpi_object *package;
         int rev, num, ret = -EINVAL;
 
-        status = acpi_evaluate_object(handle, "_PUR", NULL, &buffer);
-        if (ACPI_FAILURE(status))
+        if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
+                return -EINVAL;
+
+        if (!buffer.length || !buffer.pointer)
                 return -EINVAL;
+
         package = buffer.pointer;
         if (package->type != ACPI_TYPE_PACKAGE || package->package.count != 2)
                 goto out;
         rev = package->package.elements[0].integer.value;
         num = package->package.elements[1].integer.value;
-        if (rev != 1)
+        if (rev != 1 || num < 0)
                 goto out;
         *num_cpus = num;
         ret = 0;
@@ -409,7 +415,7 @@ static void acpi_pad_ost(acpi_handle handle, int stat,
 
 static void acpi_pad_handle_notify(acpi_handle handle)
 {
-        int num_cpus, ret;
+        int num_cpus;
         uint32_t idle_cpus;
 
         mutex_lock(&isolated_cpus_lock);
@@ -417,12 +423,9 @@ static void acpi_pad_handle_notify(acpi_handle handle)
                 mutex_unlock(&isolated_cpus_lock);
                 return;
         }
-        ret = acpi_pad_idle_cpus(num_cpus);
+        acpi_pad_idle_cpus(num_cpus);
         idle_cpus = acpi_pad_idle_cpus_num();
-        if (!ret)
-                acpi_pad_ost(handle, 0, idle_cpus);
-        else
-                acpi_pad_ost(handle, 1, 0);
+        acpi_pad_ost(handle, 0, idle_cpus);
         mutex_unlock(&isolated_cpus_lock);
 }