From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A7A161F186 for ; Tue, 25 Jul 2023 20:27:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8EEFEC433C8; Tue, 25 Jul 2023 20:26:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690316821; bh=gEzQPMn8Qpqa1JNOX+vH1aewrhLcYcM6fFBfClUEv/8=; h=From:To:Cc:Subject:Date:From; b=sJOSbA51Ti/uusknlq3hcUajShgMVP5z/PCyoNDaQKCdcs/uUIgZfXCX1UG1v0Oot my+3xnrTIt+cx7D1BZtbLrFTLldGkUUGrwVNRzH3n2oKhj4yR2G3AZhbpKqXDEYj+a twITw/WPtdabfmBPL6L4tWn6j7GYpJFgOWIxUxh+KCeNryHCSaxm6YHiINcP7MXc8l JQjvVQaLkbcYjJhKC+Q/PngVugBOQFKn7zfKu8nj4iswQ7Vzsk04tbSLVT0n6WQM20 wnrOvnfOKUCFX6HIjA5b6NUW5fzMIN5jA464TDQKcFU/9rytA81/bvOZ5+VKjdFWf2 8Fi3j79i7PbBg== From: Arnd Bergmann To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Hou Tao Cc: Arnd Bergmann , Alexei Starovoitov , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Kumar Kartikeya Dwivedi , bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] [v2] bpf: work around -Wuninitialized warning Date: Tue, 25 Jul 2023 22:26:40 +0200 Message-Id: <20230725202653.2905259-1-arnd@kernel.org> X-Mailer: git-send-email 2.39.2 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Arnd Bergmann 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 --- 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 51d6389e5152e..14d9b1a9a4cac 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); -- 2.39.2