2 files changed, 15 insertions, 0 deletions

diff --git a/drivers/cpufreq/speedstep-lib.c b/drivers/cpufreq/speedstep-lib.c
index 7047821a7f8a..4ab7a2156672 100644
--- a/drivers/cpufreq/speedstep-lib.c
+++ b/drivers/cpufreq/speedstep-lib.c
@@ -400,6 +400,7 @@ unsigned int speedstep_get_freqs(enum speedstep_processor processor,
 
         pr_debug("previous speed is %u\n", prev_speed);
 
+        preempt_disable();
         local_irq_save(flags);
 
         /* switch to low state */
@@ -464,6 +465,8 @@ unsigned int speedstep_get_freqs(enum speedstep_processor processor,
 
 out:
         local_irq_restore(flags);
+        preempt_enable();
+
         return ret;
 }
 EXPORT_SYMBOL_GPL(speedstep_get_freqs);
diff --git a/drivers/cpufreq/speedstep-smi.c b/drivers/cpufreq/speedstep-smi.c
index 5fc96d5d656b..819229e824fb 100644
--- a/drivers/cpufreq/speedstep-smi.c
+++ b/drivers/cpufreq/speedstep-smi.c
@@ -156,6 +156,7 @@ static void speedstep_set_state(unsigned int state)
                 return;
 
         /* Disable IRQs */
+        preempt_disable();
         local_irq_save(flags);
 
         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
@@ -166,9 +167,19 @@ static void speedstep_set_state(unsigned int state)
 
         do {
                 if (retry) {
+                        /*
+                         * We need to enable interrupts, otherwise the blockage
+                         * won't resolve.
+                         *
+                         * We disable preemption so that other processes don't
+                         * run. If other processes were running, they could
+                         * submit more DMA requests, making the blockage worse.
+                         */
                         pr_debug("retry %u, previous result %u, waiting...\n",
                                         retry, result);
+                        local_irq_enable();
                         mdelay(retry * 50);
+                        local_irq_disable();
                 }
                 retry++;
                 __asm__ __volatile__(
@@ -185,6 +196,7 @@ static void speedstep_set_state(unsigned int state)
 
         /* enable IRQs */
         local_irq_restore(flags);
+        preempt_enable();
 
         if (new_state == state)
                 pr_debug("change to %u MHz succeeded after %u tries "