NULL pointer might be used in ips_monitor()

 The patch is to create ips_adjust thread before ips_monitor begins
 to run  because the latter will kthread_stop() or wake up the former
 via ips->adjust pointer. Without this change, it is possible that
 ips->adjust is NULL when kthread_stop() or wake_up_process() is
 called in ips_monitor().

Signed-off-by: minskey guo <chaohong.guo@intel.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

1 files changed, 13 insertions, 9 deletions

diff --git a/drivers/platform/x86/intel_ips.c b/drivers/platform/x86/intel_ips.c
index 71dcc410f9d..bfa9c726054 100644
--- a/drivers/platform/x86/intel_ips.c
+++ b/drivers/platform/x86/intel_ips.c
@@ -940,7 +940,6 @@ static int ips_monitor(void *data)
                 kfree(mch_samples);
                 kfree(cpu_samples);
                 kfree(mchp_samples);
-                kthread_stop(ips->adjust);
                 return -ENOMEM;
         }
 
@@ -1535,19 +1534,24 @@ static int ips_probe(struct pci_dev *dev, const struct pci_device_id *id)
         ips_enable_cpu_turbo(ips);
         ips->cpu_turbo_enabled = true;
 
-        /* Set up the work queue and monitor/adjust threads */
-        ips->monitor = kthread_run(ips_monitor, ips, "ips-monitor");
-        if (IS_ERR(ips->monitor)) {
+        /* Create thermal adjust thread */
+        ips->adjust = kthread_create(ips_adjust, ips, "ips-adjust");
+        if (IS_ERR(ips->adjust)) {
                 dev_err(&dev->dev,
-                        "failed to create thermal monitor thread, aborting\n");
+                        "failed to create thermal adjust thread, aborting\n");
                 ret = -ENOMEM;
                 goto error_free_irq;
+
         }
 
-        ips->adjust = kthread_create(ips_adjust, ips, "ips-adjust");
-        if (IS_ERR(ips->adjust)) {
+        /*
+         * Set up the work queue and monitor thread. The monitor thread
+         * will wake up ips_adjust thread.
+         */
+        ips->monitor = kthread_run(ips_monitor, ips, "ips-monitor");
+        if (IS_ERR(ips->monitor)) {
                 dev_err(&dev->dev,
-                        "failed to create thermal adjust thread, aborting\n");
+                        "failed to create thermal monitor thread, aborting\n");
                 ret = -ENOMEM;
                 goto error_thread_cleanup;
         }
@@ -1566,7 +1570,7 @@ static int ips_probe(struct pci_dev *dev, const struct pci_device_id *id)
         return ret;
 
 error_thread_cleanup:
-        kthread_stop(ips->monitor);
+        kthread_stop(ips->adjust);
 error_free_irq:
         free_irq(ips->dev->irq, ips);
 error_unmap: