> -----Original Message-----
> From: David Marchand <david.march...@redhat.com>
> Sent: Tuesday, July 8, 2025 1:28 PM
> To: dev@dpdk.org
> Cc: sta...@dpdk.org; Bruce Richardson <bruce.richard...@intel.com>; Gage Eads
> <gage.e...@intel.com>; Olivier Matz
> <olivier.m...@6wind.com>; Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>
> Subject: [PATCH v3 09/18] stack: fix unaligned accesses on 128-bit
>
> Caught by UBSan:
>
> ../lib/eal/x86/include/rte_atomic_64.h:206:21: runtime error:
> member access within misaligned address 0x7ffd9c67f228 for
> type 'const rte_int128_t', which requires 16 byte alignment
> 0x7ffd9c67f228: note: pointer points here
> 00 00 00 00 c0 5d 3e 00 01 00 00 00 01 00 00 00 00 00 00 00
> ^
> 00 00 00 00 00 00 00 00 00 00 00 00
> SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
> ../lib/eal/x86/include/rte_atomic_64.h:206:21 in
> ../lib/eal/x86/include/rte_atomic_64.h:206:21: runtime error:
> member access within misaligned address 0x7ffd9c67f228 for type
> 'const union rte_int128_t::(anonymous at
> ../lib/eal/include/generic/rte_atomic.h:1102:2)', which requires
> 16 byte alignment
> 0x7ffd9c67f228: note: pointer points here
> 00 00 00 00 c0 5d 3e 00 01 00 00 00 01 00 00 00 00 00 00 00
> ^
> 00 00 00 00 00 00 00 00 00 00 00 00
> SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
> ../lib/eal/x86/include/rte_atomic_64.h:206:21 in
> ../lib/eal/x86/include/rte_atomic_64.h:206:16: runtime error:
> load of misaligned address 0x7ffd9c67f228 for type
> 'const uint64_t' (aka 'const unsigned long'), which requires
> 16 byte alignment
> 0x7ffd9c67f228: note: pointer points here
> 00 00 00 00 c0 5d 3e 00 01 00 00 00 01 00 00 00 00 00 00 00
> ^
> 00 00 00 00 00 00 00 00 00 00 00 00
> SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
> ../lib/eal/x86/include/rte_atomic_64.h:206:21 in
>
> Fixes: 3340202f5954 ("stack: add lock-free implementation")
> Cc: sta...@dpdk.org
>
> Signed-off-by: David Marchand <david.march...@redhat.com>
> Acked-by: Bruce Richardson <bruce.richard...@intel.com>
> ---
> lib/stack/rte_stack_lf_c11.h | 8 ++++----
> lib/stack/rte_stack_lf_generic.h | 8 ++++----
> 2 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/lib/stack/rte_stack_lf_c11.h b/lib/stack/rte_stack_lf_c11.h
> index b97e02d6a1..f674731235 100644
> --- a/lib/stack/rte_stack_lf_c11.h
> +++ b/lib/stack/rte_stack_lf_c11.h
> @@ -63,13 +63,13 @@ __rte_stack_lf_push_elems(struct rte_stack_lf_list *list,
> struct rte_stack_lf_elem *last,
> unsigned int num)
> {
> - struct rte_stack_lf_head old_head;
> + alignas(16) struct rte_stack_lf_head old_head;
> int success;
>
> old_head = list->head;
>
> do {
> - struct rte_stack_lf_head new_head;
> + alignas(16) struct rte_stack_lf_head new_head;
>
> /* Swing the top pointer to the first element in the list and
> * make the last element point to the old top.
> @@ -102,7 +102,7 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
> void **obj_table,
> struct rte_stack_lf_elem **last)
> {
> - struct rte_stack_lf_head old_head;
> + alignas(16) struct rte_stack_lf_head old_head;
> uint64_t len;
> int success = 0;
>
> @@ -129,7 +129,7 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
>
> /* Pop num elements */
> do {
> - struct rte_stack_lf_head new_head;
> + alignas(16) struct rte_stack_lf_head new_head;
> struct rte_stack_lf_elem *tmp;
> unsigned int i;
>
> diff --git a/lib/stack/rte_stack_lf_generic.h
> b/lib/stack/rte_stack_lf_generic.h
> index cc69e4d168..32f56dffdd 100644
> --- a/lib/stack/rte_stack_lf_generic.h
> +++ b/lib/stack/rte_stack_lf_generic.h
> @@ -36,13 +36,13 @@ __rte_stack_lf_push_elems(struct rte_stack_lf_list *list,
> struct rte_stack_lf_elem *last,
> unsigned int num)
> {
> - struct rte_stack_lf_head old_head;
> + alignas(16) struct rte_stack_lf_head old_head;
> int success;
>
> old_head = list->head;
>
> do {
> - struct rte_stack_lf_head new_head;
> + alignas(16) struct rte_stack_lf_head new_head;
>
> /* An acquire fence (or stronger) is needed for weak memory
> * models to establish a synchronized-with relationship between
> @@ -77,7 +77,7 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
> void **obj_table,
> struct rte_stack_lf_elem **last)
> {
> - struct rte_stack_lf_head old_head;
> + alignas(16) struct rte_stack_lf_head old_head;
> int success = 0;
>
> /* Reserve num elements, if available */
> @@ -99,7 +99,7 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
>
> /* Pop num elements */
> do {
> - struct rte_stack_lf_head new_head;
> + alignas(16) struct rte_stack_lf_head new_head;
> struct rte_stack_lf_elem *tmp;
> unsigned int i;
>
> --
Acked-by: Konstantin Ananyev <konstantin.anan...@huawei.com>
> 2.50.0
