The previous fix 18effad9cfa7 ("stack: reload head when pop fails") only changed C11 implementation, not generic implementation. List head must be loaded right before continue (when failed to find the new head). Without this, one thread might keep trying and failing to pop items without ever loading the new correct head. Fixes: 3340202f5954 ("stack: add lock-free implementation") Cc: gage.eads@intel.com Cc: stable@dpdk.org Signed-off-by: Julien Meunier <julien.meunier@nokia.com> --- lib/stack/rte_stack_lf_generic.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/lib/stack/rte_stack_lf_generic.h b/lib/stack/rte_stack_lf_generic.h index 4850a05ee7..7fa29cedb2 100644 --- a/lib/stack/rte_stack_lf_generic.h +++ b/lib/stack/rte_stack_lf_generic.h @@ -128,8 +128,10 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list, /* If NULL was encountered, the list was modified while * traversing it. Retry. */ - if (i != num) + if (i != num) { + old_head = list->head; continue; + } new_head.top = tmp; new_head.cnt = old_head.cnt + 1; -- 2.17.1
The previous commit 18effad9cfa7 ("stack: reload head when pop fails") only changed C11 implementation, not generic implementation. List head must be loaded right before continue (when failed to find the new head). Without this, one thread might keep trying and failing to pop items without ever loading the new correct head. Fixes: 3340202f5954 ("stack: add lock-free implementation") Cc: stable@dpdk.org Signed-off-by: Julien Meunier <julien.meunier@nokia.com> --- v2: * rebase * update commit log + remove invalid CC email address lib/stack/rte_stack_lf_generic.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/lib/stack/rte_stack_lf_generic.h b/lib/stack/rte_stack_lf_generic.h index 4850a05ee7..7fa29cedb2 100644 --- a/lib/stack/rte_stack_lf_generic.h +++ b/lib/stack/rte_stack_lf_generic.h @@ -128,8 +128,10 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list, /* If NULL was encountered, the list was modified while * traversing it. Retry. */ - if (i != num) + if (i != num) { + old_head = list->head; continue; + } new_head.top = tmp; new_head.cnt = old_head.cnt + 1; -- 2.17.1
Hello,
On Tue, Sep 21, 2021 at 06:17:24PM +0200, Julien Meunier wrote:
> The previous commit 18effad9cfa7 ("stack: reload head when pop fails")
> only changed C11 implementation, not generic implementation.
>
> List head must be loaded right before continue (when failed to find the
> new head). Without this, one thread might keep trying and failing to pop
> items without ever loading the new correct head.
>
> Fixes: 3340202f5954 ("stack: add lock-free implementation")
> Cc: stable@dpdk.org
>
> Signed-off-by: Julien Meunier <julien.meunier@nokia.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
Thanks Julien!
24/09/2021 10:57, Olivier Matz:
> Hello,
>
> On Tue, Sep 21, 2021 at 06:17:24PM +0200, Julien Meunier wrote:
> > The previous commit 18effad9cfa7 ("stack: reload head when pop fails")
> > only changed C11 implementation, not generic implementation.
> >
> > List head must be loaded right before continue (when failed to find the
> > new head). Without this, one thread might keep trying and failing to pop
> > items without ever loading the new correct head.
> >
> > Fixes: 3340202f5954 ("stack: add lock-free implementation")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Julien Meunier <julien.meunier@nokia.com>
>
> Acked-by: Olivier Matz <olivier.matz@6wind.com>
Applied, thanks.