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Drivers: hv: Notify the host of permanent hot-add failures 

If memory hot-add fails with the error -EEXIST, then this is a permanent
failure. Notify the host of this information, so the host will not attempt
hot-add again. If the failure were a transient failure, host will attempt
a hot-add after some delay.

In this version of the patch, I have added some additional comments
to clarify how the host treats different failure conditions.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
K. Y. Srinivasan 2013-03-18 13:51:38 -07:00 committed by Greg Kroah-Hartman
parent f766dc1ea5
commit 7f4f2302a1
1 changed files with 31 additions and 2 deletions
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33
drivers/hv/hv_balloon.c
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@ -590,6 +590,16 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size,
if (ret) {
pr_info("hot_add memory failed error is %d\n", ret);
if (ret == -EEXIST) {
/*
* This error indicates that the error
* is not a transient failure. This is the
* case where the guest's physical address map
* precludes hot adding memory. Stop all further
* memory hot-add.
*/
do_hot_add = false;
}
has->ha_end_pfn -= HA_CHUNK;
has->covered_end_pfn -= processed_pfn;
break;
@ -849,11 +859,30 @@ static void hot_add_req(struct work_struct *dummy)
rg_sz = region_size;
}
resp.page_count = process_hot_add(pg_start, pfn_cnt,
rg_start, rg_sz);
if (do_hot_add)
resp.page_count = process_hot_add(pg_start, pfn_cnt,
rg_start, rg_sz);
#endif
/*
* The result field of the response structure has the
* following semantics:
*
* 1. If all or some pages hot-added: Guest should return success.
*
* 2. If no pages could be hot-added:
*
* If the guest returns success, then the host
* will not attempt any further hot-add operations. This
* signifies a permanent failure.
*
* If the guest returns failure, then this failure will be
* treated as a transient failure and the host may retry the
* hot-add operation after some delay.
*/
if (resp.page_count > 0)
resp.result = 1;
else if (!do_hot_add)
resp.result = 1;
else
resp.result = 0;