From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f42.google.com (mail-wm1-f42.google.com [209.85.128.42]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5F61418E3F for ; Sun, 21 Apr 2024 20:16:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.42 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713730598; cv=none; b=QNTphfzl8vdwD4/YvwJ9hC+tE/22zW2+ekoyHDQHVtKpNPNju8Gv9dLwDlghTY4gfZhdXDp9d8jyaP3IgknRwh2XJ/2IJQY952BHhHLDFyrcsO+P3bAgCAbjNSIHUvU/WdOD9Mw2aE2ufgGylniBoLC/YSAVJ698Ejuny9WCE/4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713730598; c=relaxed/simple; bh=xoy0QWiuFCjG2awDfTEByQ69ZKSMJ0t97vOflr4J5G4=; h=From:Date:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VABVfbWw2x/QZhRRzcT49hKhvP4F8LehwAxJ/K1yVKddjcP4n/GwyugZq5nepnVRWEGeVBP9XkhcD5unGIjWnsSSLLjbOPaLBVlQ4sWReV91rHQPmQ8j/kYa+TLdaeDwzEBbIf4Im25ykbk4OML7lCll0cLjGRbzMNtINvFsuuc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=eJkJPZ/3; arc=none smtp.client-ip=209.85.128.42 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="eJkJPZ/3" Received: by mail-wm1-f42.google.com with SMTP id 5b1f17b1804b1-41a51803dceso2556055e9.3 for ; Sun, 21 Apr 2024 13:16:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1713730595; x=1714335395; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date:message-id:reply-to; bh=ypknRuVyxeEw7V5WbZzbZAN8JMPNVshRCUTqCF710qs=; b=eJkJPZ/3eKfRveXvp71IE/WkXCkkjrX3Jk1QmjjLve8xZa3Bi7JdNT3D/jQgAV0k+F fvetQTLUz6CgNIqSdOcgs7Y+wBL/+IDicGKO5SMnovz29CFTDXpftyesXxEfkYvBABtF bM3fHi2/XbC15efdofI23HJig4RLuAH0euPc6woVp9kPsrJ3HzdRRWNPr/HhTweRO72d 4oqPq6exBy5Ce7S/Dq7dnpUqsfWQNJ68Z7ukcp1VMgdUWQl/Tv/IhQ/O5bi9/6Gid0KJ oStF4xMSyu4vWzfR07WHS76vu0W8foChDJqEz/9K6ICcUr7DWIzm0WW6sFf31AJBYb4M oh6Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1713730595; x=1714335395; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=ypknRuVyxeEw7V5WbZzbZAN8JMPNVshRCUTqCF710qs=; b=l/s0Q/NyobBYZF1+o+zbKTHlj1FmNj9Cu90dmlPAFOszYIe2/qaCf7GCaRCnYtA47g 0TRJe5s9cb1NWRBDGEDtdmclX6irKViEsBRaUBffxYRaSJdiIHw+BK+2JxG5+rYnhZny regRYd6I7t/MsCcA/lH5Z1bkNDkLjTXM/Lu2xRBGQxYic3lGHgGmgf59td5DPiiUBnG9 5TJ3kAU+CRr6pIyYlnGcoXDlvX6WxwhwMhdHqL6wFTlAxE3HyqbHyfnS5BO0TMK0vQXL AvK37uW5styvgt3qO2gcxru12IBQ4u0kvwcxzsusZus7Zvt8Bu8f2lPH296aV+Lv1v1V qdLw== X-Gm-Message-State: AOJu0YxMbE/EUDGVuzmcn1B33zIk5iZaXUcfBzHMx5WiiNITKPm+gmhW jrCJnVavgofr+lFWIoRfuAbTf/M2BFpvkb0bIfaror1acoNbULy8 X-Google-Smtp-Source: AGHT+IGtnH8aCa1kYX8o0qnBaChv50Os3tRa1NRchkmViBxdPRph45WESTNytlBxX50Hw465QomkMw== X-Received: by 2002:a05:600c:4ecb:b0:418:e7b6:21de with SMTP id g11-20020a05600c4ecb00b00418e7b621demr7138016wmq.23.1713730594399; Sun, 21 Apr 2024 13:16:34 -0700 (PDT) Received: from krava ([83.240.61.103]) by smtp.gmail.com with ESMTPSA id q6-20020a05600c46c600b0041892857924sm14368345wmo.36.2024.04.21.13.16.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 21 Apr 2024 13:16:34 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Sun, 21 Apr 2024 22:16:32 +0200 To: Siddharth Chintamaneni Cc: bpf@vger.kernel.org, alexei.starovoitov@gmail.com, daniel@iogearbox.net, Jiri Olsa , andrii@kernel.org, Yonghong Song , "Craun, Milo" , "Sahu, Raj" , Roop Anna , "Williams, Dan" Subject: Re: [PATCH bpf-next] Add notrace to queued_spin_lock_slowpath function to avoid deadlocks Message-ID: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sat, Apr 20, 2024 at 05:45:17AM -0400, Siddharth Chintamaneni wrote: > This patch is to prevent deadlocks when multiple bpf > programs are attached to queued_spin_locks functions. This issue is similar > to what is already discussed [1] before with the spin_lock helpers. > > The addition of notrace macro to the queued_spin_locks > has been discussed [2] when bpf_spin_locks are introduced. > > [1] https://lore.kernel.org/bpf/CAE5sdEigPnoGrzN8WU7Tx-h-iFuMZgW06qp0KHWtpvoXxf1OAQ@mail.gmail.com/#r > [2] https://lore.kernel.org/all/20190117011629.efxp7abj4bpf5yco@ast-mbp/t/#maf05c4d71f935f3123013b7ed410e4f50e9da82c > > Fixes: d83525ca62cf ("bpf: introduce bpf_spin_lock") > Signed-off-by: Siddharth Chintamaneni > --- > kernel/locking/qspinlock.c | 2 +- > .../bpf/prog_tests/tracing_failure.c | 24 +++++++++++++++++++ > .../selftests/bpf/progs/tracing_failure.c | 6 +++++ > 3 files changed, 31 insertions(+), 1 deletion(-) > > diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c > index ebe6b8ec7cb3..4d46538d8399 100644 > --- a/kernel/locking/qspinlock.c > +++ b/kernel/locking/qspinlock.c > @@ -313,7 +313,7 @@ static __always_inline u32 > __pv_wait_head_or_lock(struct qspinlock *lock, > * contended : (*,x,y) +--> (*,0,0) ---> (*,0,1) -' : > * queue : ^--' : > */ > -void __lockfunc queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) > +notrace void __lockfunc queued_spin_lock_slowpath(struct qspinlock > *lock, u32 val) > { > struct mcs_spinlock *prev, *next, *node; > u32 old, tail; > diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_failure.c > b/tools/testing/selftests/bpf/prog_tests/tracing_failure.c > index a222df765bc3..822ee6c559bc 100644 > --- a/tools/testing/selftests/bpf/prog_tests/tracing_failure.c > +++ b/tools/testing/selftests/bpf/prog_tests/tracing_failure.c > @@ -28,10 +28,34 @@ static void test_bpf_spin_lock(bool is_spin_lock) > tracing_failure__destroy(skel); > } > > +static void test_queued_spin_lock(void) > +{ > + struct tracing_failure *skel; > + int err; hi, the patch seems to be mangled, tabs are missing you might find some help in Documentation/process/email-clients.rst jirka > + > + skel = tracing_failure__open(); > + if (!ASSERT_OK_PTR(skel, "tracing_failure__open")) > + return; > + > + bpf_program__set_autoload(skel->progs.test_queued_spin_lock, true); > + > + err = tracing_failure__load(skel); > + if (!ASSERT_OK(err, "tracing_failure__load")) > + goto out; > + > + err = tracing_failure__attach(skel); > + ASSERT_ERR(err, "tracing_failure__attach"); > + > +out: > + tracing_failure__destroy(skel); > +} > + > void test_tracing_failure(void) > { > if (test__start_subtest("bpf_spin_lock")) > test_bpf_spin_lock(true); > if (test__start_subtest("bpf_spin_unlock")) > test_bpf_spin_lock(false); > + if (test__start_subtest("queued_spin_lock_slowpath")) > + test_queued_spin_lock(); > } > diff --git a/tools/testing/selftests/bpf/progs/tracing_failure.c > b/tools/testing/selftests/bpf/progs/tracing_failure.c > index d41665d2ec8c..2d2e7fc9d4f0 100644 > --- a/tools/testing/selftests/bpf/progs/tracing_failure.c > +++ b/tools/testing/selftests/bpf/progs/tracing_failure.c > @@ -18,3 +18,9 @@ int BPF_PROG(test_spin_unlock, struct bpf_spin_lock *lock) > { > return 0; > } > + > +SEC("?fentry/queued_spin_lock_slowpath") > +int BPF_PROG(test_queued_spin_lock, struct qspinlock *lock, u32 val) > +{ > + return 0; > +} > -- > 2.43.0