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>

diff --git a/drivers/acpi/acpica/hwxface.c b/drivers/acpi/acpica/hwxface.c
index 5ee7a814cd9207db34d42b8945867e415ab733bb..f81fb068d20ed34613615d76217841e2c7297ad4 100644 (file)
--- 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)