From 63e2da3b7f7f63f881aa508825b0c4241e9910e1 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 25 Jul 2023 22:26:40 +0200 Subject: [PATCH] bpf: work around -Wuninitialized warning Splitting these out into separate helper functions means that we actually pass an uninitialized variable into another function call if dec_active() happens to not be inlined, and CONFIG_PREEMPT_RT is disabled: kernel/bpf/memalloc.c: In function 'add_obj_to_free_list': kernel/bpf/memalloc.c:200:9: error: 'flags' is used uninitialized [-Werror=uninitialized] 200 | dec_active(c, flags); Avoid this by passing the flags by reference, so they either get initialized and dereferenced through a pointer, or the pointer never gets accessed at all. Fixes: 18e027b1c7c6d ("bpf: Factor out inc/dec of active flag into helpers.") Suggested-by: Alexei Starovoitov Signed-off-by: Arnd Bergmann Link: https://lore.kernel.org/r/20230725202653.2905259-1-arnd@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/memalloc.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 51d6389..14d9b1a 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -183,11 +183,11 @@ static void inc_active(struct bpf_mem_cache *c, unsigned long *flags) WARN_ON_ONCE(local_inc_return(&c->active) != 1); } -static void dec_active(struct bpf_mem_cache *c, unsigned long flags) +static void dec_active(struct bpf_mem_cache *c, unsigned long *flags) { local_dec(&c->active); if (IS_ENABLED(CONFIG_PREEMPT_RT)) - local_irq_restore(flags); + local_irq_restore(*flags); } static void add_obj_to_free_list(struct bpf_mem_cache *c, void *obj) @@ -197,7 +197,7 @@ static void add_obj_to_free_list(struct bpf_mem_cache *c, void *obj) inc_active(c, &flags); __llist_add(obj, &c->free_llist); c->free_cnt++; - dec_active(c, flags); + dec_active(c, &flags); } /* Mostly runs from irq_work except __init phase. */ @@ -344,7 +344,7 @@ static void free_bulk(struct bpf_mem_cache *c) cnt = --c->free_cnt; else cnt = 0; - dec_active(c, flags); + dec_active(c, &flags); if (llnode) enque_to_free(tgt, llnode); } while (cnt > (c->high_watermark + c->low_watermark) / 2); @@ -384,7 +384,7 @@ static void check_free_by_rcu(struct bpf_mem_cache *c) llist_for_each_safe(llnode, t, llist_del_all(&c->free_llist_extra_rcu)) if (__llist_add(llnode, &c->free_by_rcu)) c->free_by_rcu_tail = llnode; - dec_active(c, flags); + dec_active(c, &flags); } if (llist_empty(&c->free_by_rcu)) @@ -408,7 +408,7 @@ static void check_free_by_rcu(struct bpf_mem_cache *c) inc_active(c, &flags); WRITE_ONCE(c->waiting_for_gp.first, __llist_del_all(&c->free_by_rcu)); c->waiting_for_gp_tail = c->free_by_rcu_tail; - dec_active(c, flags); + dec_active(c, &flags); if (unlikely(READ_ONCE(c->draining))) { free_all(llist_del_all(&c->waiting_for_gp), !!c->percpu_size); -- 2.7.4