From nobody Sat Nov 15 17:07:32 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1749667011; cv=none; d=zohomail.com; s=zohoarc; b=ayeAmwZpIvBoZ5DQr9ZVn86wEBnR5ZQ31/k0gHE7o3J4vfq9Pbba1Yk4OaEJj4BMovqFyjTVDUtwGAoZsOkYBqBGLT6YhhLvNAmUcXBxBBKIwsn4mmzEcPVlEoLmxFjQmM9HuecGiC1FapeJGNgrA+dF1vvnTeBT6LqXpXvFPUE= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1749667011; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=lJ0vZgBOtVyV/kxbsVrweB7URiKy+WNZJU2nYcVkU88=; b=BOSHjQg62UKEPEokLt7NaIjafXGamPy+JsP9db0s1lSLLFDh5rll5cueFkFqhYsQZHS0gya+dGCwWAs/E9aSZf4ce2Z42Tw+0t43VVHl30MXuy+0oBMJ7SIWtAHE6EMZQ922LiGKiJ8wt4yHOYNIIqR2sgc3NWAILW4yOVgkyOM= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1749667011426148.50611974652713; Wed, 11 Jun 2025 11:36:51 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uPQFB-0003uc-16; Wed, 11 Jun 2025 14:32:14 -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 1uPQAh-0002Zz-Vm for qemu-devel@nongnu.org; Wed, 11 Jun 2025 14:27:36 -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 1uPQAc-0001mP-2X for qemu-devel@nongnu.org; Wed, 11 Jun 2025 14:27:35 -0400 Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-538-Q0_R4qAbOxyb2Wxe-FzFjA-1; Wed, 11 Jun 2025 14:27:26 -0400 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id F403819560A7; Wed, 11 Jun 2025 18:27:21 +0000 (UTC) Received: from localhost (unknown [10.2.16.122]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 3B0091956094; Wed, 11 Jun 2025 18:27:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1749666449; 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=lJ0vZgBOtVyV/kxbsVrweB7URiKy+WNZJU2nYcVkU88=; b=ez+/NvcIRWouQudZdo+LWJb7nRNDp+yuZgM3n9SilMLzgrLwIK9h+EIxdRhSPIpTOzrN9d Bfc4ZjA5qclGGtr+/gBj5OSZsbZOCH24moJ7h1B2VXwKWDQaga/Kw7asK46n3NOZvNNBpK SidoUnWZNF6i4jUuekLND8+8JxWC0xg= X-MC-Unique: Q0_R4qAbOxyb2Wxe-FzFjA-1 X-Mimecast-MFC-AGG-ID: Q0_R4qAbOxyb2Wxe-FzFjA_1749666442 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?= , Klaus Jensen Subject: [PULL 28/31] hw/scsi/megasas: skip automatic zero-init of large arrays Date: Wed, 11 Jun 2025 14:25:30 -0400 Message-ID: <20250611182533.200590-29-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: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1749667013266116600 From: Daniel P. Berrang=C3=A9 The 'megasas_dcmd_pd_get_list' and 'megasas_dcmd_get_properties' methods have 4k structs used for copying data from the device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'info' structs are manually initialized with memset(). The compiler ought to be intelligent enough to turn the memset() into a static initialization operation, and thus not duplicate the automatic zero-init. Replacing memset() with '{}' makes it unambiguous that the arrays are statically initialized. Signed-off-by: Daniel P. Berrang=C3=A9 Reviewed-by: Stefan Hajnoczi Reviewed-by: Klaus Jensen Reviewed-by: Harsh Prateek Bora Message-id: 20250610123709.835102-29-berrange@redhat.com Signed-off-by: Stefan Hajnoczi --- hw/scsi/megasas.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c index 55cd188bd5..844643d916 100644 --- a/hw/scsi/megasas.c +++ b/hw/scsi/megasas.c @@ -981,13 +981,11 @@ static int megasas_event_wait(MegasasState *s, Megasa= sCmd *cmd) =20 static int megasas_dcmd_pd_get_list(MegasasState *s, MegasasCmd *cmd) { - struct mfi_pd_list info; - size_t dcmd_size =3D sizeof(info); + struct mfi_pd_list info =3D {}; BusChild *kid; uint32_t offset, dcmd_limit, num_pd_disks =3D 0, max_pd_disks; dma_addr_t residual; =20 - memset(&info, 0, dcmd_size); offset =3D 8; dcmd_limit =3D offset + sizeof(struct mfi_pd_address); if (cmd->iov_size < dcmd_limit) { @@ -1429,11 +1427,10 @@ static int megasas_dcmd_cfg_read(MegasasState *s, M= egasasCmd *cmd) =20 static int megasas_dcmd_get_properties(MegasasState *s, MegasasCmd *cmd) { - struct mfi_ctrl_props info; + struct mfi_ctrl_props info =3D {}; size_t dcmd_size =3D sizeof(info); dma_addr_t residual; =20 - memset(&info, 0x0, dcmd_size); if (cmd->iov_size < dcmd_size) { trace_megasas_dcmd_invalid_xfer_len(cmd->index, cmd->iov_size, dcmd_size); --=20 2.49.0