ACPICA: acpi_read: On error, do not modify the return value target location.

If an error happens in the middle of a split 32/32 64-bit I/O
operation, do not modify the target of the return value pointer.
Makes the code consistent with the rest of ACPICA. Bjorn Helgaas.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 14 insertions, 12 deletions

diff --git a/drivers/acpi/acpica/hwxface.c b/drivers/acpi/acpica/hwxface.c
index 5ee7a814cd92..f81fb068d20e 100644
--- a/drivers/acpi/acpica/hwxface.c
+++ b/drivers/acpi/acpica/hwxface.c
@@ -119,7 +119,8 @@ ACPI_EXPORT_SYMBOL(acpi_reset)
  ******************************************************************************/
 acpi_status acpi_read(u64 *return_value, struct acpi_generic_address *reg)
 {
-        u32 value;
+        u32 value_lo;
+        u32 value_hi;
         u32 width;
         u64 address;
         acpi_status status;
@@ -137,13 +138,8 @@ acpi_status acpi_read(u64 *return_value, struct acpi_generic_address *reg)
                 return (status);
         }
 
-        /* Initialize entire 64-bit return value to zero */
-
-        *return_value = 0;
-        value = 0;
-
         /*
-         * Two address spaces supported: Memory or IO. PCI_Config is
+         * Two address spaces supported: Memory or I/O. PCI_Config is
          * not supported here because the GAS structure is insufficient
          */
         if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
@@ -155,29 +151,35 @@ acpi_status acpi_read(u64 *return_value, struct acpi_generic_address *reg)
                 }
         } else {                /* ACPI_ADR_SPACE_SYSTEM_IO, validated earlier */
 
+                value_lo = 0;
+                value_hi = 0;
+
                 width = reg->bit_width;
                 if (width == 64) {
                         width = 32;     /* Break into two 32-bit transfers */
                 }
 
                 status = acpi_hw_read_port((acpi_io_address)
-                                           address, &value, width);
+                                           address, &value_lo, width);
                 if (ACPI_FAILURE(status)) {
                         return (status);
                 }
-                *return_value = value;
 
                 if (reg->bit_width == 64) {
 
                         /* Read the top 32 bits */
 
                         status = acpi_hw_read_port((acpi_io_address)
-                                                   (address + 4), &value, 32);
+                                                   (address + 4), &value_hi,
+                                                   32);
                         if (ACPI_FAILURE(status)) {
                                 return (status);
                         }
-                        *return_value |= ((u64)value << 32);
                 }
+
+                /* Set the return value only if status is AE_OK */
+
+                *return_value = (value_lo | ((u64)value_hi << 32));
         }
 
         ACPI_DEBUG_PRINT((ACPI_DB_IO,
@@ -186,7 +188,7 @@ acpi_status acpi_read(u64 *return_value, struct acpi_generic_address *reg)
                           ACPI_FORMAT_UINT64(address),
                           acpi_ut_get_region_name(reg->space_id)));
 
-        return (status);
+        return (AE_OK);
 }
 
 ACPI_EXPORT_SYMBOL(acpi_read)