From patchwork Thu Jul 8 01:18:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexei Starovoitov X-Patchwork-Id: 472260 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CEAB5C07E9C for ; Thu, 8 Jul 2021 01:18:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B77B661206 for ; Thu, 8 Jul 2021 01:18:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230192AbhGHBVZ (ORCPT ); Wed, 7 Jul 2021 21:21:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230106AbhGHBVV (ORCPT ); Wed, 7 Jul 2021 21:21:21 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8BAA0C061574; Wed, 7 Jul 2021 18:18:39 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id h1-20020a17090a3d01b0290172d33bb8bcso4875593pjc.0; Wed, 07 Jul 2021 18:18:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=bGv8lt8RNeoYZwAKXokdTr6gAVZv4YRPbRC8p2kgseY=; b=rYCUSmOf/IelQ/rcTCFbPfWkLsRHlpb4lFh94Opbdm+YlN7Ai1d/YQvQDmZJo6JzOX IkQ9nEH9a0TLmOpXQwuDgxYeqYjpG6hrJnDAv9gurpoepztepeQotla7HbpWeIdOVYYd yJ8oZThO4Ld05YI1qCXcKdqhRUsZ1tvHpp7B3UgYWVr7yBIeUO1GELX+sfUpB7jiAbXk FRJ2/SddgvRUTGpPUCEErmHiUqLVcNdR3z8VRxdewoGhRNZJO9nyFQU3L8LMjd83EeUC I38NrN70fbT6vaSR9MEEL3pkgakWqmcAgTSOatuCfcgsSAUcO6NhuX6HDtOEg8qEVawq Q+4A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=bGv8lt8RNeoYZwAKXokdTr6gAVZv4YRPbRC8p2kgseY=; b=YJPtAJPFHjPNnDIV5YjmZ2/5HGgYXqPX4GGTam1wfCUTsEn0C+gWyUZw1XKVRDxSE4 rGaAe7gjaMtgB5T+q5Y236wCRRgE2U/FWhszjquoWlGKzjV3HbufRHelZS+7KOnDxE4H sjGpovxJwPEPKtd6cBzbyHaHdJEGn/2SfpV5gjakFS0lRdCjmO0SVeD/OfX/7iNQjw/V ec99GOE4pWl0DKhy9epf347Y7JLfYBiSXKTBrGKIPRlYjhwDBAwZdd6qYqZ2oyNxZ1vZ vQ5oy/IFL5gipyw3NoTiSQ7voRBQ/2p4Zj1N4Q94QKpL1j+hgRP4loICl3I3a5ayYZ4N qEIg== X-Gm-Message-State: AOAM533D64IsOwyGjBMdWrPaGHKy168VcF5d6pXgFzS848xlsM0hkH0F WY6znw75iXrSUBKNpCkAqejmScmZqlk= X-Google-Smtp-Source: ABdhPJwabfMSPTbWecpunDLS+PRr/U1kalg3dSuzDKCUxrnuiRd6yMx8VZn7ED0v7Z3mdk3TQHAxkQ== X-Received: by 2002:a17:902:b94a:b029:10d:6f56:eeac with SMTP id h10-20020a170902b94ab029010d6f56eeacmr23879819pls.54.1625707119133; Wed, 07 Jul 2021 18:18:39 -0700 (PDT) Received: from ast-mbp.thefacebook.com ([2620:10d:c090:400::5:9f4e]) by smtp.gmail.com with ESMTPSA id d20sm417450pfn.219.2021.07.07.18.18.37 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 07 Jul 2021 18:18:38 -0700 (PDT) From: Alexei Starovoitov To: davem@davemloft.net Cc: daniel@iogearbox.net, andrii@kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, kernel-team@fb.com Subject: [PATCH v5 bpf-next 01/11] bpf: Prepare bpf_prog_put() to be called from irq context. Date: Wed, 7 Jul 2021 18:18:23 -0700 Message-Id: <20210708011833.67028-2-alexei.starovoitov@gmail.com> X-Mailer: git-send-email 2.13.5 In-Reply-To: <20210708011833.67028-1-alexei.starovoitov@gmail.com> References: <20210708011833.67028-1-alexei.starovoitov@gmail.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Alexei Starovoitov Currently bpf_prog_put() is called from the task context only. With addition of bpf timers the timer related helpers will start calling bpf_prog_put() from irq-saved region and in rare cases might drop the refcnt to zero. To address this case, first, convert bpf_prog_free_id() to be irq-save (this is similar to bpf_map_free_id), and, second, defer non irq appropriate calls into work queue. For example: bpf_audit_prog() is calling kmalloc and wake_up_interruptible, bpf_prog_kallsyms_del_all()->bpf_ksym_del()->spin_unlock_bh(). They are not safe with irqs disabled. Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index e343f158e556..5d1fee634be8 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1699,6 +1699,8 @@ static int bpf_prog_alloc_id(struct bpf_prog *prog) void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock) { + unsigned long flags; + /* cBPF to eBPF migrations are currently not in the idr store. * Offloaded programs are removed from the store when their device * disappears - even if someone grabs an fd to them they are unusable, @@ -1708,7 +1710,7 @@ void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock) return; if (do_idr_lock) - spin_lock_bh(&prog_idr_lock); + spin_lock_irqsave(&prog_idr_lock, flags); else __acquire(&prog_idr_lock); @@ -1716,7 +1718,7 @@ void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock) prog->aux->id = 0; if (do_idr_lock) - spin_unlock_bh(&prog_idr_lock); + spin_unlock_irqrestore(&prog_idr_lock, flags); else __release(&prog_idr_lock); } @@ -1752,14 +1754,32 @@ static void __bpf_prog_put_noref(struct bpf_prog *prog, bool deferred) } } +static void bpf_prog_put_deferred(struct work_struct *work) +{ + struct bpf_prog_aux *aux; + struct bpf_prog *prog; + + aux = container_of(work, struct bpf_prog_aux, work); + prog = aux->prog; + perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_UNLOAD, 0); + bpf_audit_prog(prog, BPF_AUDIT_UNLOAD); + __bpf_prog_put_noref(prog, true); +} + static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock) { - if (atomic64_dec_and_test(&prog->aux->refcnt)) { - perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_UNLOAD, 0); - bpf_audit_prog(prog, BPF_AUDIT_UNLOAD); + struct bpf_prog_aux *aux = prog->aux; + + if (atomic64_dec_and_test(&aux->refcnt)) { /* bpf_prog_free_id() must be called first */ bpf_prog_free_id(prog, do_idr_lock); - __bpf_prog_put_noref(prog, true); + + if (in_irq() || irqs_disabled()) { + INIT_WORK(&aux->work, bpf_prog_put_deferred); + schedule_work(&aux->work); + } else { + bpf_prog_put_deferred(&aux->work); + } } }