Fix ACPI processor power block initialization

Properly clear the memory, and set "pr->flags.power" only if a C2 or
deeper state is valid (to make the code match both the comment and
previous behaviour).

This fixes a boot-time lockup reported by Maneesh Soni when using
"maxcpus=1".

Acked-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 10 deletions

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 573b6a97bb1f..70d8a6ec0920 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -514,8 +514,6 @@ static int acpi_processor_set_power_policy(struct acpi_processor *pr)
 
 static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr)
 {
-        int i;
-
         ACPI_FUNCTION_TRACE("acpi_processor_get_power_info_fadt");
 
         if (!pr)
@@ -524,8 +522,7 @@ static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr)
         if (!pr->pblk)
                 return_VALUE(-ENODEV);
 
-        for (i = 0; i < ACPI_PROCESSOR_MAX_POWER; i++)
-                memset(pr->power.states, 0, sizeof(struct acpi_processor_cx));
+        memset(pr->power.states, 0, sizeof(pr->power.states));
 
         /* if info is obtained from pblk/fadt, type equals state */
         pr->power.states[ACPI_STATE_C1].type = ACPI_STATE_C1;
@@ -555,13 +552,9 @@ static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr)
 
 static int acpi_processor_get_power_info_default_c1(struct acpi_processor *pr)
 {
-        int i;
-
         ACPI_FUNCTION_TRACE("acpi_processor_get_power_info_default_c1");
 
-        for (i = 0; i < ACPI_PROCESSOR_MAX_POWER; i++)
-                memset(&(pr->power.states[i]), 0,
-                       sizeof(struct acpi_processor_cx));
+        memset(pr->power.states, 0, sizeof(pr->power.states));
 
         /* if info is obtained from pblk/fadt, type equals state */
         pr->power.states[ACPI_STATE_C1].type = ACPI_STATE_C1;
@@ -873,7 +866,8 @@ static int acpi_processor_get_power_info(struct acpi_processor *pr)
         for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
                 if (pr->power.states[i].valid) {
                         pr->power.count = i;
-                        pr->flags.power = 1;
+                        if (pr->power.states[i].type >= ACPI_STATE_C2)
+                                pr->flags.power = 1;
                 }
         }