s390/cmf: simplify copy_block

cmf_copy_block tries to ensure data consistency by copying the
channel measurement block twice and comparing the data. This was
needed on very old machines only. Nowadays we guarantee
consistency by copying the data when the channel is idle.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/drivers/s390/cio/cmf.c b/drivers/s390/cio/cmf.c
index 7ed6c865501b00c863609b3bde374017892c4712..531861d005fd828b0b486ecfcd353185eba89396 100644 (file)
--- a/drivers/s390/cio/cmf.c
+++ b/drivers/s390/cio/cmf.c
@@ -280,12 +280,9 @@ void retry_set_schib(struct ccw_device *cdev)
 
 static int cmf_copy_block(struct ccw_device *cdev)
 {
-       struct subchannel *sch;
-       void *reference_buf;
-       void *hw_block;
+       struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct cmb_data *cmb_data;
-
-       sch = to_subchannel(cdev->dev.parent);
+       void *hw_block;
 
        if (cio_update_schib(sch))
                return -ENODEV;
@@ -300,19 +297,8 @@ static int cmf_copy_block(struct ccw_device *cdev)
        }
        cmb_data = cdev->private->cmb;
        hw_block = cmb_data->hw_block;
-       if (!memcmp(cmb_data->last_block, hw_block, cmb_data->size))
-               /* No need to copy. */
-               return 0;
-       reference_buf = kzalloc(cmb_data->size, GFP_ATOMIC);
-       if (!reference_buf)
-               return -ENOMEM;
-       /* Ensure consistency of block copied from hardware. */
-       do {
-               memcpy(cmb_data->last_block, hw_block, cmb_data->size);
-               memcpy(reference_buf, hw_block, cmb_data->size);
-       } while (memcmp(cmb_data->last_block, reference_buf, cmb_data->size));
+       memcpy(cmb_data->last_block, hw_block, cmb_data->size);
        cmb_data->last_update = get_tod_clock();
-       kfree(reference_buf);
        return 0;
 }