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powerpc/pseries: minor enhancements in dlpar_memory_remove_by_ic() 

We don't need the 'lmbs_available' variable to count the valid LMBs and
to check if we have less than 'lmbs_to_remove'. We must ensure that the
entire LMB range must be removed, so we can error out immediately if any
LMB in the range is marked as reserved.

Add a couple of comments explaining the reasoning behind the differences
we have in this function in contrast to what it is done in its sister
function, dlpar_memory_remove_by_count().

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210512202809.95363-5-danielhb413@gmail.com
This commit is contained in:
Daniel Henrique Barboza 2021-05-12 17:28:09 -03:00 committed by Michael Ellerman
parent 163e792175
commit 40999b041e
1 changed files with 19 additions and 9 deletions
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28
arch/powerpc/platforms/pseries/hotplug-memory.c
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@ -517,7 +517,6 @@ static int dlpar_memory_remove_by_index(u32 drc_index)
static int dlpar_memory_remove_by_ic(u32 lmbs_to_remove, u32 drc_index)
{
struct drmem_lmb *lmb, *start_lmb, *end_lmb;
int lmbs_available = 0;
int rc;
pr_info("Attempting to hot-remove %u LMB(s) at %x\n",
@ -530,18 +529,29 @@ static int dlpar_memory_remove_by_ic(u32 lmbs_to_remove, u32 drc_index)
if (rc)
return -EINVAL;
/* Validate that there are enough LMBs to satisfy the request */
/*
* Validate that all LMBs in range are not reserved. Note that it
* is ok if they are !ASSIGNED since our goal here is to remove the
* LMB range, regardless of whether some LMBs were already removed
* by any other reason.
*
* This is a contrast to what is done in remove_by_count() where we
* check for both RESERVED and !ASSIGNED (via lmb_is_removable()),
* because we want to remove a fixed amount of LMBs in that function.
*/
for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) {
if (lmb->flags & DRCONF_MEM_RESERVED)
break;
lmbs_available++;
if (lmb->flags & DRCONF_MEM_RESERVED) {
pr_err("Memory at %llx (drc index %x) is reserved\n",
lmb->base_addr, lmb->drc_index);
return -EINVAL;
}
}
if (lmbs_available < lmbs_to_remove)
return -EINVAL;
for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) {
/*
* dlpar_remove_lmb() will error out if the LMB is already
* !ASSIGNED, but this case is a no-op for us.
*/
if (!(lmb->flags & DRCONF_MEM_ASSIGNED))
continue;