From patchwork Thu Jun 20 13:21:55 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sebastian Andrzej Siewior X-Patchwork-Id: 13705504 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 52E651AD9FE; Thu, 20 Jun 2024 13:27:34 +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=1718890056; cv=none; b=pktgu3Rm07l/Ek1JvsVCq6jhQ0FxGd3Rl3ILJkcy/8tkQklEx/9zV/xn2aSNHeTFjgriyEler8YsIzbZBUFibVhti0UmFlTZ9brEpPmkvDbuwS8vuCpnB2P/7A7mcK2CGKQPUhOYEJ+bPSgcIgBg8g8bsQ7ya8bwjaQFFyCW6+4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718890056; c=relaxed/simple; bh=3nOCXH40kHfZO87SmAo125DaEM6dygak/4wmXIHT9LM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=g/tHQuEmlAzIQfyr7mOzfvfbQy4EMr41fo8iLcMPW+suWkNy7hH5AXGPkAaVGUXxRUlW64s4MEViX1xCSUH32pfh+2XK8rd3kxYYPraLNVoVKhSyEM91qLYS5qI3k5ebWzBYxL/gnejWO4sMhY65uN5Q8WjOf0+tgPnm/ihrPBI= 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=WRwvst7i; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=1hOCoxC+; 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="WRwvst7i"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="1hOCoxC+" From: Sebastian Andrzej Siewior DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1718890052; 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=+6ZJx97XD1+mNbkUbduQBaAsweYRZijjNDkdfe4a/D8=; b=WRwvst7igjw+oqXza4+poXOay6yxtULqHXKpREkVOwZzKqb2c+BjWaqAbIwVgm6Nplg6uf Zt3QCJtdL8JD9geDduUxurPeEJ6gshCDIyaRI85+oc5NmITsjy9Zq335mSSn+lBCKuJMcD v1FrTgx0n4iBV8mgVYxk4GZ8lQdovEP25mdS1XGsYf328DFL0ucQA/F9E3zDzoyAqTu1N0 Ff+QDWlgxEWhOH+njVaZ1f86er06UFP8maFIPIKLtTv9xDMxbZBEuWqJ176WeCTSBPizsZ S/hV1GD8EN//okad1w05PzOk5CSAHUKVsklkjhaXKbNlU+fee5nvDwzmnDkJ1g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1718890052; 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=+6ZJx97XD1+mNbkUbduQBaAsweYRZijjNDkdfe4a/D8=; b=1hOCoxC+I0HRBAzNW5LCsfg0Mpu+I4563svs+h6FK91CdptEUoVdFsB0WMF46nP2Qe4sO8 KwoFaFTLn1cih3Bw== To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Cc: "David S. Miller" , Daniel Bristot de Oliveira , 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 , David Ahern Subject: [PATCH v9 net-next 05/15] net/tcp_sigpool: Use nested-BH locking for sigpool_scratch. Date: Thu, 20 Jun 2024 15:21:55 +0200 Message-ID: <20240620132727.660738-6-bigeasy@linutronix.de> In-Reply-To: <20240620132727.660738-1-bigeasy@linutronix.de> References: <20240620132727.660738-1-bigeasy@linutronix.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org sigpool_scratch 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. Make a struct with a pad member (original sigpool_scratch) and a local_lock_t 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: David Ahern Signed-off-by: Sebastian Andrzej Siewior --- net/ipv4/tcp_sigpool.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/net/ipv4/tcp_sigpool.c b/net/ipv4/tcp_sigpool.c index 8512cb09ebc09..d8a4f192873a2 100644 --- a/net/ipv4/tcp_sigpool.c +++ b/net/ipv4/tcp_sigpool.c @@ -10,7 +10,14 @@ #include static size_t __scratch_size; -static DEFINE_PER_CPU(void __rcu *, sigpool_scratch); +struct sigpool_scratch { + local_lock_t bh_lock; + void __rcu *pad; +}; + +static DEFINE_PER_CPU(struct sigpool_scratch, sigpool_scratch) = { + .bh_lock = INIT_LOCAL_LOCK(bh_lock), +}; struct sigpool_entry { struct crypto_ahash *hash; @@ -72,7 +79,7 @@ static int sigpool_reserve_scratch(size_t size) break; } - old_scratch = rcu_replace_pointer(per_cpu(sigpool_scratch, cpu), + old_scratch = rcu_replace_pointer(per_cpu(sigpool_scratch.pad, cpu), scratch, lockdep_is_held(&cpool_mutex)); if (!cpu_online(cpu) || !old_scratch) { kfree(old_scratch); @@ -93,7 +100,7 @@ static void sigpool_scratch_free(void) int cpu; for_each_possible_cpu(cpu) - kfree(rcu_replace_pointer(per_cpu(sigpool_scratch, cpu), + kfree(rcu_replace_pointer(per_cpu(sigpool_scratch.pad, cpu), NULL, lockdep_is_held(&cpool_mutex))); __scratch_size = 0; } @@ -277,7 +284,8 @@ int tcp_sigpool_start(unsigned int id, struct tcp_sigpool *c) __cond_acquires(RC /* Pairs with tcp_sigpool_reserve_scratch(), scratch area is * valid (allocated) until tcp_sigpool_end(). */ - c->scratch = rcu_dereference_bh(*this_cpu_ptr(&sigpool_scratch)); + local_lock_nested_bh(&sigpool_scratch.bh_lock); + c->scratch = rcu_dereference_bh(*this_cpu_ptr(&sigpool_scratch.pad)); return 0; } EXPORT_SYMBOL_GPL(tcp_sigpool_start); @@ -286,6 +294,7 @@ void tcp_sigpool_end(struct tcp_sigpool *c) __releases(RCU_BH) { struct crypto_ahash *hash = crypto_ahash_reqtfm(c->req); + local_unlock_nested_bh(&sigpool_scratch.bh_lock); rcu_read_unlock_bh(); ahash_request_free(c->req); crypto_free_ahash(hash);