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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9A8A9C71141 for ; Wed, 11 Jun 2025 18:36:00 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uPQAr-0002xp-Qx; Wed, 11 Jun 2025 14:27:45 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uPQ9q-0001ay-Qy for qemu-devel@nongnu.org; Wed, 11 Jun 2025 14:26:44 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uPQ9g-0001Ir-VL for qemu-devel@nongnu.org; Wed, 11 Jun 2025 14:26:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1749666379; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=a+3IbSd15/rc8GUbCSOu3df+NumonRFcoNFm3e5bolg=; b=IEdLxosoS1xJFxZDZ/8kB19jWXyVdCLrrV5EwxfWNV5BgNJ0NKIRgu+PTRr9zllRCStXFU ZhG8TPFEAu418p31oce9Z7pbSOeb6mE9/oXpoUoHQfJ19W0gobXuNEMF1Dm8pWTai9vVXu hOcjjtdvbyuh/2Ni3gT8GkEcIVA5thg= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-622-Q6Hs_-hbPnyFGqvz5I4myw-1; Wed, 11 Jun 2025 14:26:16 -0400 X-MC-Unique: Q6Hs_-hbPnyFGqvz5I4myw-1 X-Mimecast-MFC-AGG-ID: Q6Hs_-hbPnyFGqvz5I4myw_1749666372 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 216D1180028F; Wed, 11 Jun 2025 18:26:11 +0000 (UTC) Received: from localhost (unknown [10.2.16.122]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 624F218003FC; Wed, 11 Jun 2025 18:26:06 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: qemu-ppc@nongnu.org, Daniel Henrique Barboza , qemu-block@nongnu.org, Jesper Devantier , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Peter Maydell , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Harsh Prateek Bora , Troy Lee , Paolo Bonzini , Hanna Reitz , qemu-s390x@nongnu.org, Halil Pasic , Kevin Wolf , "Michael S. Tsirkin" , qemu-trivial@nongnu.org, Dmitry Fleytman , Jason Wang , Keith Busch , Nicholas Piggin , =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Barrat?= , Fam Zheng , Sven Schnelle , Stefan Hajnoczi , Joel Stanley , Gerd Hoffmann , "Edgar E. Iglesias" , qemu-arm@nongnu.org, Hannes Reinecke , Klaus Jensen , Jeuk Kim , Andrew Jeffery , Alistair Francis , Thomas Huth , Michael Tokarev , Laurent Vivier , Rob Herring , Steven Lee , Jamin Lin , Christian Borntraeger , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Subject: [PULL 05/31] chardev/char-pty: skip automatic zero-init of large array Date: Wed, 11 Jun 2025 14:25:07 -0400 Message-ID: <20250611182533.200590-6-stefanha@redhat.com> In-Reply-To: <20250611182533.200590-1-stefanha@redhat.com> References: <20250611182533.200590-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Daniel P. Berrangé The 'pty_chr_read' method has a 4k byte array used for copying data between the PTY and device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buf' array will be fully initialized when reading data off the PTY. Signed-off-by: Daniel P. Berrangé Reviewed-by: Stefan Hajnoczi Message-id: 20250610123709.835102-6-berrange@redhat.com Signed-off-by: Stefan Hajnoczi --- chardev/char-pty.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/chardev/char-pty.c b/chardev/char-pty.c index c28554e6e0..674e9b3f14 100644 --- a/chardev/char-pty.c +++ b/chardev/char-pty.c @@ -154,7 +154,7 @@ static gboolean pty_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque) Chardev *chr = CHARDEV(opaque); PtyChardev *s = PTY_CHARDEV(opaque); gsize len; - uint8_t buf[CHR_READ_BUF_LEN]; + QEMU_UNINITIALIZED uint8_t buf[CHR_READ_BUF_LEN]; ssize_t ret; len = sizeof(buf); -- 2.49.0