From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 56DBFC2BA4C for ; Tue, 25 Jan 2022 03:15:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242149AbiAYDKb (ORCPT ); Mon, 24 Jan 2022 22:10:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40208 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S3412038AbiAYAfe (ORCPT ); Mon, 24 Jan 2022 19:35:34 -0500 Received: from mail-il1-x12e.google.com (mail-il1-x12e.google.com [IPv6:2607:f8b0:4864:20::12e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8E47BC0617A4 for ; Mon, 24 Jan 2022 14:19:30 -0800 (PST) Received: by mail-il1-x12e.google.com with SMTP id o10so15253492ilh.0 for ; Mon, 24 Jan 2022 14:19:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=THQAUN1mbEudksIDDLPlW1QcJyiqdIPagdOlq/nWl68=; b=N0Q7pEz89wajTQyGT34jsiXokry693HX1d/6w9o68POeEL8q2BRjMv+sKQTsI4gErG KmpgO7wgcvFAFFIqyan7LEsl8Uv07ZavMglwtF29yLw/GGCd6dMPMz2vTmjU5hh+pKnu yzoOfkvzzGD3/AMR5e+BfuKcvU9tb7begoXDEVJgvv8BQGW0kjvLsvPOTj+bPiOUztGQ HiFfVl078xESly6WoD4Zp3RdEQppfbTCCZExmen2iAnDAWtpyAs8ssZAD8fZ/ujiwo55 4weve12HC+A4z7jMowYtHoXKoVqpSm/j4EbhnQRKVOXGxTDcAoNAzC/5/dZW5OXC3zox 2Z7w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=THQAUN1mbEudksIDDLPlW1QcJyiqdIPagdOlq/nWl68=; b=STjWsEDWyqQ72fF6a/twRmlg4zC+c58vNuA8IepM71rHzDu0AJlTpEi44Vm6nsrovU lYl33hHXApXSAMpOtdOFBUBOzShpsy2kJYugmTGSjdhdV9A+dsmjjh5t1FJgRHMiDJ+5 smsFbDCdt8J1kCT8CF96LY4n+a8HUyjrJf9iuTZ+GgGpZcxhOOCuwbPVO/z7ly3T/tin u/SZ8ZjztO981H7wfDUwju3Rf0AnXvLEHLowEGDXgS7R+hIBuunTAnMZuWi0T4nDNggL Jty9lS04y8aGO+W9w70V2JpSxo03RBTRks1pT6eawNLmNWxkSMLroO/EggtYdD6Yceez 0thQ== X-Gm-Message-State: AOAM530/grZyBNpCGeSQq5xYuaJEBi44oMne3E6Qp0z0B2J5LauR/g5Z Gj8wyE45VZjWNZaCRiyZISbS2VnprOzRigorsnWFJu/Dbgk= X-Google-Smtp-Source: ABdhPJyG1XdeGNpFeSpUzgr19rqvHdDDAXUevKiy+/Q9edpnQapIsLcNy9CLeVN079axBcaKX7TLHC6+2WB+9W4+D4I= X-Received: by 2002:a92:db0b:: with SMTP id b11mr9789637iln.98.1643062769974; Mon, 24 Jan 2022 14:19:29 -0800 (PST) MIME-Version: 1.0 References: <20220113233158.1582743-1-kennyyu@fb.com> <20220124185403.468466-1-kennyyu@fb.com> <20220124185403.468466-2-kennyyu@fb.com> In-Reply-To: <20220124185403.468466-2-kennyyu@fb.com> From: Andrii Nakryiko Date: Mon, 24 Jan 2022 14:19:18 -0800 Message-ID: Subject: Re: [PATCH v7 bpf-next 1/4] bpf: Add support for bpf iterator programs to use sleepable helpers To: Kenny Yu Cc: Andrii Nakryiko , Alexei Starovoitov , bpf , Daniel Borkmann , Yonghong Song , Alexei Starovoitov , Gabriele Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Mon, Jan 24, 2022 at 10:54 AM Kenny Yu wrote: > > This patch allows bpf iterator programs to use sleepable helpers by > changing `bpf_iter_run_prog` to use the appropriate synchronization. > With sleepable bpf iterator programs, we can no longer use > `rcu_read_lock()` and must use `rcu_read_lock_trace()` instead > to protect the bpf program. > > Signed-off-by: Kenny Yu > --- Acked-by: Andrii Nakryiko > kernel/bpf/bpf_iter.c | 20 +++++++++++++++----- > 1 file changed, 15 insertions(+), 5 deletions(-) > > diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c > index b7aef5b3416d..110029ede71e 100644 > --- a/kernel/bpf/bpf_iter.c > +++ b/kernel/bpf/bpf_iter.c > @@ -5,6 +5,7 @@ > #include > #include > #include > +#include > > struct bpf_iter_target_info { > struct list_head list; > @@ -684,11 +685,20 @@ int bpf_iter_run_prog(struct bpf_prog *prog, void *ctx) > { > int ret; > > - rcu_read_lock(); > - migrate_disable(); > - ret = bpf_prog_run(prog, ctx); > - migrate_enable(); > - rcu_read_unlock(); > + if (prog->aux->sleepable) { > + rcu_read_lock_trace(); > + migrate_disable(); > + might_fault(); > + ret = bpf_prog_run(prog, ctx); > + migrate_enable(); > + rcu_read_unlock_trace(); > + } else { > + rcu_read_lock(); > + migrate_disable(); > + ret = bpf_prog_run(prog, ctx); > + migrate_enable(); > + rcu_read_unlock(); > + } > > /* bpf program can only return 0 or 1: > * 0 : okay > -- > 2.30.2 >