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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 F22A9C433E3 for ; Wed, 24 Jun 2020 20:12:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFB0520823 for ; Wed, 24 Jun 2020 20:12:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593029575; bh=TnQiolA6D8Fm8sLu96I73u+4PGM+rRJ0dDA/VI0CGrA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=PuPugCcQpCJyGioTBQ+zXskrg7gcm9hICcdkUgb3QMzlaJLWcRRVLa03Lm1SunSbt sSP3bvpG9DX7hxLNErMOCRtN9iQxBDIwxqNeuEKgFjtb/6FsxyF7vyqw7vbwXfYRWV lCurmzsU1b/BXODH2pI23GorXIFaEn4mogcTSKRo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406449AbgFXUMz (ORCPT ); Wed, 24 Jun 2020 16:12:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:52436 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406398AbgFXUMc (ORCPT ); Wed, 24 Jun 2020 16:12:32 -0400 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 736F720857; Wed, 24 Jun 2020 20:12:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593029551; bh=TnQiolA6D8Fm8sLu96I73u+4PGM+rRJ0dDA/VI0CGrA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=icLKrPawcATtokb2umksIhSUxFECFh0BKx/yFZqtsXZvfMAqTE/uaeNWyCUF2hyqt oJQlOEtr9dfobKnUMsAmh1z7panEjTcgIqFFQkBkulZ1+HwdBoGDZwMS/yNht77+4S mAvANqIFzobfG4ieOFdNuX4XylwwNmtboiLlBskw= From: paulmck@kernel.org To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Uladzislau Rezki (Sony)" , "Paul E . McKenney" Subject: [PATCH tip/core/rcu 16/17] rcu: Introduce single argument kvfree_rcu() interface Date: Wed, 24 Jun 2020 13:12:25 -0700 Message-Id: <20200624201226.21197-16-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200624201200.GA28901@paulmck-ThinkPad-P72> References: <20200624201200.GA28901@paulmck-ThinkPad-P72> Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: "Uladzislau Rezki (Sony)" Make kvfree_rcu() capable of freeing objects that will not embed an rcu_head within it. This saves storage overhead in such objects. Reclaiming headless objects this way requires only a single argument (pointer to the object). After this patch, there are two ways to use kvfree_rcu(): a) kvfree_rcu(ptr, rhf); struct X { struct rcu_head rhf; unsigned char data[100]; }; void *ptr = kvmalloc(sizeof(struct X), GFP_KERNEL); if (ptr) kvfree_rcu(ptr, rhf); b) kvfree_rcu(ptr); void *ptr = kvmalloc(some_bytes, GFP_KERNEL); if (ptr) kvfree_rcu(ptr); Note that the headless usage (example b) can only be used in a code that can sleep. This is enforced by the CONFIG_DEBUG_ATOMIC_SLEEP option. Co-developed-by: Joel Fernandes (Google) Reviewed-by: Joel Fernandes (Google) Signed-off-by: Uladzislau Rezki (Sony) Signed-off-by: Paul E. McKenney --- include/linux/rcupdate.h | 38 ++++++++++++++++++++++++++++++++++---- 1 file changed, 34 insertions(+), 4 deletions(-) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 51b26ab..d15d46d 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -877,12 +877,42 @@ do { \ /** * kvfree_rcu() - kvfree an object after a grace period. - * @ptr: pointer to kvfree - * @rhf: the name of the struct rcu_head within the type of @ptr. * - * Same as kfree_rcu(), just simple alias. + * This macro consists of one or two arguments and it is + * based on whether an object is head-less or not. If it + * has a head then a semantic stays the same as it used + * to be before: + * + * kvfree_rcu(ptr, rhf); + * + * where @ptr is a pointer to kvfree(), @rhf is the name + * of the rcu_head structure within the type of @ptr. + * + * When it comes to head-less variant, only one argument + * is passed and that is just a pointer which has to be + * freed after a grace period. Therefore the semantic is + * + * kvfree_rcu(ptr); + * + * where @ptr is a pointer to kvfree(). + * + * Please note, head-less way of freeing is permitted to + * use from a context that has to follow might_sleep() + * annotation. Otherwise, please switch and embed the + * rcu_head structure within the type of @ptr. */ -#define kvfree_rcu(ptr, rhf) kfree_rcu(ptr, rhf) +#define kvfree_rcu(...) KVFREE_GET_MACRO(__VA_ARGS__, \ + kvfree_rcu_arg_2, kvfree_rcu_arg_1)(__VA_ARGS__) + +#define KVFREE_GET_MACRO(_1, _2, NAME, ...) NAME +#define kvfree_rcu_arg_2(ptr, rhf) kfree_rcu(ptr, rhf) +#define kvfree_rcu_arg_1(ptr) \ +do { \ + typeof(ptr) ___p = (ptr); \ + \ + if (___p) \ + kvfree_call_rcu(NULL, (rcu_callback_t) (___p)); \ +} while (0) /* * Place this after a lock-acquisition primitive to guarantee that -- 2.9.5