On 20/07/2021 15:38, Leonardo Brás wrote:
Hello Fred, thanks for this feedback!
Sorry if I miss anything, this snippet was written for v1 over an year
ago, and I have not taken a look at it ever since.
On Mon, 2021-07-19 at 15:53 +0200, Frederic Barrat wrote:
On 16/07/2021 10:27, Leonardo Bras wrote:
@@ -1099,18 +1105,13 @@ int iommu_take_ownership(struct iommu_table
*tbl)
for (i = 0; i < tbl->nr_pools; i++)
spin_lock_nest_lock(&tbl->pools[i].lock, &tbl-
large_pool.lock);
- iommu_table_release_pages(tbl);
-
- if (!bitmap_empty(tbl->it_map, tbl->it_size)) {
+ if (iommu_table_in_use(tbl)) {
pr_err("iommu_tce: it_map is not empty");
ret = -EBUSY;
- /* Undo iommu_table_release_pages, i.e. restore
bit#0, etc */
- iommu_table_reserve_pages(tbl, tbl-
it_reserved_start,
- tbl->it_reserved_end);
- } else {
- memset(tbl->it_map, 0xff, sz);
}
+ memset(tbl->it_map, 0xff, sz);
+
So if the table is not empty, we fail (EBUSY) but we now also
completely
overwrite the bitmap. It was in an unexpected state, but we're making
it
worse. Or am I missing something?
IIRC there was a reason to do that at the time, but TBH I don't really
remember it, and by looking at the code right now you seem to be
correct about this causing trouble.
I will send a v6 fixing it soon.
Please review the remaining patches for some issue I may be missing.
Alexey, any comments on that?
Agree with Fred, this is a bug, EBUSY is not that unexpected :-/ Thanks,
Fred
Again, thank you for reviewing Fred!
Best regards,
Leonardo Bras
--
Alexey
