From patchwork Fri May 3 18:25:17 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sebastian Sewior X-Patchwork-Id: 13653305 X-Patchwork-Delegate: kuba@kernel.org Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 CD63C1591F1; Fri, 3 May 2024 18:30:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714761014; cv=none; b=I+mFn6yyVje1Bguv9xqS2xgzMADEFWtS/MEafynthM4AEIIxJTB3z60z8aOyoxWRrnorsOMBr9N3B00e6rAvZ9sTg4NaaXXAehG7oPuWox1I4gV2HyblIndKk6yFd6u6KEBgMRUBD3DMCpR1mdFxzSkr1DtbcN59rcX5jVQmFxw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714761014; c=relaxed/simple; bh=6fVCWFsuEBR7nJV+h+rv294+QgH0Wy9inghRo5IE69k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jPQ37TuQFkOM/Y5JDnR5HNrjrR8pRmyt2G0TUjYAOMf/mofmu2iCvhsJ9ulWxuc+hkPUKnbv29m/KiGcL9N4wALC+qsPWfCj529+Wx2QWFSmhNl6h6emidcAU0Qba7fl8/h1Q3bCq4WcoqPjWX1kHvAcM3fn902ip6Uycr49vxY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=hpW97fX4; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Ssmiv9hm; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="hpW97fX4"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Ssmiv9hm" From: Sebastian Andrzej Siewior DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1714761010; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0ybrNKVMPkZ4Ap31+Up4JCU5gLeDUDgUGDfpmjWAnCM=; b=hpW97fX4evbEt0tWQbOvOP61Uj5ksTD/64vN6UYwBwECNGgT89P7IQWlYezsnZ67Vymtsq tcpqYqRCHoHti+ZTXiAH6um/7o3j4E/Q9+4tZofYYGvCT+PXrmdizM0DXsQGjV9mRlASuv 6j1l6KxjNZfuZGxEcX4NgQX6tMfzfW5WW+0vLvDyLkEWmxuhuz9HxvQE8OdBFniSeZN1DN WGs3YnW8oe0vS+tt4hpZnFTNgWIgkbd4oamLnQm/kv5tTEZVjtTb7chdKRotAY+k0RKpiX UavJJ4P/QnD4G9qBVkAYCpc2hdpToj+O1lgSnoBEqGQD2QKyYMVuoVtFv6lwkA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1714761010; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0ybrNKVMPkZ4Ap31+Up4JCU5gLeDUDgUGDfpmjWAnCM=; b=Ssmiv9hmiUSp1iHRdezmkdqkkK3COLazKJDAi/W/DvYC0fZ3hOoM1UGn1Om40iRt7c5xvm RlcAOAQLtBV9HVCQ== To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Cc: "David S. Miller" , Boqun Feng , Daniel Borkmann , Eric Dumazet , Frederic Weisbecker , Ingo Molnar , Jakub Kicinski , Paolo Abeni , Peter Zijlstra , Thomas Gleixner , Waiman Long , Will Deacon , Sebastian Andrzej Siewior , Alexei Starovoitov , Andrii Nakryiko , Hao Luo , Jiri Olsa , John Fastabend , KP Singh , Martin KaFai Lau , Song Liu , Stanislav Fomichev , Yonghong Song , bpf@vger.kernel.org Subject: [PATCH net-next 13/15] net: Use nested-BH locking for bpf_scratchpad. Date: Fri, 3 May 2024 20:25:17 +0200 Message-ID: <20240503182957.1042122-14-bigeasy@linutronix.de> In-Reply-To: <20240503182957.1042122-1-bigeasy@linutronix.de> References: <20240503182957.1042122-1-bigeasy@linutronix.de> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org bpf_scratchpad is a per-CPU variable and relies on disabled BH for its locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT this data structure requires explicit locking. Add a local_lock_t to the data structure and use local_lock_nested_bh() for locking. This change adds only lockdep coverage and does not alter the functional behaviour for !PREEMPT_RT. Cc: Alexei Starovoitov Cc: Andrii Nakryiko Cc: Hao Luo Cc: Jiri Olsa Cc: John Fastabend Cc: KP Singh Cc: Martin KaFai Lau Cc: Song Liu Cc: Stanislav Fomichev Cc: Yonghong Song Cc: bpf@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior --- net/core/filter.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/core/filter.c b/net/core/filter.c index cfe8ea59fd9db..e95b235a1e4f4 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1658,9 +1658,12 @@ struct bpf_scratchpad { __be32 diff[MAX_BPF_STACK / sizeof(__be32)]; u8 buff[MAX_BPF_STACK]; }; + local_lock_t bh_lock; }; -static DEFINE_PER_CPU(struct bpf_scratchpad, bpf_sp); +static DEFINE_PER_CPU(struct bpf_scratchpad, bpf_sp) = { + .bh_lock = INIT_LOCAL_LOCK(bh_lock), +}; static inline int __bpf_try_make_writable(struct sk_buff *skb, unsigned int write_len) @@ -2029,6 +2032,7 @@ BPF_CALL_5(bpf_csum_diff, __be32 *, from, u32, from_size, diff_size > sizeof(sp->diff))) return -EINVAL; + guard(local_lock_nested_bh)(&bpf_sp.bh_lock); for (i = 0; i < from_size / sizeof(__be32); i++, j++) sp->diff[j] = ~from[i]; for (i = 0; i < to_size / sizeof(__be32); i++, j++)