[dpdk-stable] [PATCH] mem: fix alignment of requested virtual areas
Anatoly Burakov
anatoly.burakov at intel.com
Mon Jul 16 16:57:19 CEST 2018
The original code did not align any addresses that were requested as
page-aligned, but were different because addr_is_hint was set.
Below fix by Dariusz has introduced an issue where all unaligned addresses
were left as unaligned.
This patch is a partial revert of
commit 7fa7216ed48d ("mem: fix alignment of requested virtual areas")
and implements a proper fix for this issue, by asking for alignment in all
but the following two cases:
1) page size is equal to system page size, or
2) we got an aligned requested address, and will not accept a different one
This ensures that alignment is performed in all cases, except for those we
can guarantee that the address will not need alignment.
Fixes: b7cc54187ea4 ("mem: move virtual area function in common directory")
Fixes: 7fa7216ed48d ("mem: fix alignment of requested virtual areas")
Cc: dariuszx.stojaczyk at intel.com
Cc: stable at dpdk.org
Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
---
lib/librte_eal/common/eal_common_memory.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
index 659cc08f6..fbfb1b055 100644
--- a/lib/librte_eal/common/eal_common_memory.c
+++ b/lib/librte_eal/common/eal_common_memory.c
@@ -66,14 +66,17 @@ eal_get_virtual_area(void *requested_addr, size_t *size,
addr_is_hint = true;
}
- /* if requested address is not aligned by page size, or if requested
- * address is NULL, add page size to requested length as we may get an
- * address that's aligned by system page size, which can be smaller than
- * our requested page size. additionally, we shouldn't try to align if
- * system page size is the same as requested page size.
+ /* we don't need alignment of resulting pointer in the following cases:
+ *
+ * 1. page size is equal to system size
+ * 2. we have a requested address, and it is page-aligned, and we will
+ * be discarding the address if we get a different one.
+ *
+ * for all other cases, alignment is potentially necessary.
*/
no_align = (requested_addr != NULL &&
- ((uintptr_t)requested_addr & (page_sz - 1))) ||
+ requested_addr == RTE_PTR_ALIGN(requested_addr, page_sz) &&
+ !addr_is_hint) ||
page_sz == system_page_sz;
do {
--
2.17.1
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