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Fri, 31 Oct 2025 14:58:59 -0700 (PDT) Received: from localhost ([2a01:4b00:bd1f:f500:e85d:a828:282d:d5c7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-429c13e0311sm5310549f8f.30.2025.10.31.14.58.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 31 Oct 2025 14:58:58 -0700 (PDT) From: Mykyta Yatsenko To: bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, kafai@meta.com, kernel-team@meta.com, eddyz87@gmail.com, memxor@gmail.com Cc: Mykyta Yatsenko Subject: [PATCH RFC v1 2/5] bpf: refactor bpf_async_cb prog swap Date: Fri, 31 Oct 2025 21:58:32 +0000 Message-ID: <20251031-timer_nolock-v1-2-bf8266d2fb20@meta.com> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251031-timer_nolock-v1-0-bf8266d2fb20@meta.com> References: <20251031-timer_nolock-v1-0-bf8266d2fb20@meta.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit From: Mykyta Yatsenko Move the logic that swaps the bpf_prog in struct bpf_async_cb into a dedicated helper to make follow-up patches simpler. Signed-off-by: Mykyta Yatsenko --- kernel/bpf/helpers.c | 45 ++++++++++++++++++++++++++++----------------- 1 file changed, 28 insertions(+), 17 deletions(-) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index e60fea1330d40326459933170023ca3e6ffc5cee..d09c2b8989a123d6fd5a3b59efd40018c81d0149 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1351,10 +1351,34 @@ static const struct bpf_func_proto bpf_timer_init_proto = { .arg3_type = ARG_ANYTHING, }; +static int bpf_async_swap_prog(struct bpf_async_cb *cb, struct bpf_prog *prog) +{ + struct bpf_prog *prev; + + prev = cb->prog; + if (prev == prog) + return 0; + + if (prog) { + /* + * Bump prog refcnt once. Every bpf_timer_set_callback() + * can pick different callback_fn-s within the same prog. + */ + prog = bpf_prog_inc_not_zero(prog); + if (IS_ERR(prog)) + return PTR_ERR(prog); + } + if (prev) + /* Drop prev prog refcnt when swapping with new prog */ + bpf_prog_put(prev); + + cb->prog = prog; + return 0; +} + static int bpf_async_update_callback(struct bpf_async_kern *async, void *callback_fn, struct bpf_prog *prog) { - struct bpf_prog *prev; struct bpf_async_cb *cb; int err = 0; @@ -1374,22 +1398,9 @@ static int bpf_async_update_callback(struct bpf_async_kern *async, void *callbac goto out; } - prev = cb->prog; - if (prev != prog) { - /* Bump prog refcnt once. Every bpf_timer_set_callback() - * can pick different callback_fn-s within the same prog. - */ - prog = bpf_prog_inc_not_zero(prog); - if (IS_ERR(prog)) { - err = PTR_ERR(prog); - goto out; - } - if (prev) - /* Drop prev prog refcnt when swapping with new prog */ - bpf_prog_put(prev); - cb->prog = prog; - } - rcu_assign_pointer(cb->callback_fn, callback_fn); + err = bpf_async_swap_prog(cb, prog); + if (!err) + rcu_assign_pointer(cb->callback_fn, callback_fn); out: __bpf_spin_unlock_irqrestore(&async->lock); return err; -- 2.51.1