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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>
This commit is contained in:
Sebastian Ott 2017-09-06 10:44:23 +02:00 committed by Martin Schwidefsky
parent 60f3eac3a1
commit 81b050b564
1 changed files with 3 additions and 17 deletions
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20
drivers/s390/cio/cmf.c
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@ -280,12 +280,9 @@ void retry_set_schib(struct ccw_device *cdev)
static int cmf_copy_block(struct ccw_device *cdev) static int cmf_copy_block(struct ccw_device *cdev)
{ {
struct subchannel *sch; struct subchannel *sch = to_subchannel(cdev->dev.parent);
void *reference_buf;
void *hw_block;
struct cmb_data *cmb_data; struct cmb_data *cmb_data;
void *hw_block;
sch = to_subchannel(cdev->dev.parent);
if (cio_update_schib(sch)) if (cio_update_schib(sch))
return -ENODEV; return -ENODEV;
@ -300,19 +297,8 @@ static int cmf_copy_block(struct ccw_device *cdev)
} }
cmb_data = cdev->private->cmb; cmb_data = cdev->private->cmb;
hw_block = cmb_data->hw_block; hw_block = cmb_data->hw_block;
if (!memcmp(cmb_data->last_block, hw_block, cmb_data->size)) memcpy(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));
cmb_data->last_update = get_tod_clock(); cmb_data->last_update = get_tod_clock();
kfree(reference_buf);
return 0; return 0;
} }