From patchwork Fri Oct 26 13:48:01 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Saenz Julienne X-Patchwork-Id: 10657375 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C736A13BF for ; Fri, 26 Oct 2018 13:55:59 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B4D2D2C341 for ; Fri, 26 Oct 2018 13:55:59 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A68552C38A; Fri, 26 Oct 2018 13:55:59 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 3223F2C341 for ; Fri, 26 Oct 2018 13:55:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=OnE+3DeqWSyNUNhNN3xj1yvrHNtheH3Oy+4qxLPXJcc=; b=icMO44QNmpwuVM U3aoc36IeIsQOvd9DDBiiDMNrcOeNkDBKSeLnTnfCCz+n5jDyY4z91ACduUONpM3lM9FOvtuBEvvl s86BWujDNV6rvZZ2MEs+9NCKApeOPfOucfROUNJrngZG7D8RDWiWIRI6jGY3ZqjL5xqg9in9x2Gk/ 9ii23EoPbqbVWIwfn7xKJlGBAor2CJ2As9T9/4c4FJyPLvqWayhdeczcm7S+GpouKCbUZqCSlCOKF JzUUsBZfxiqUD2zVub7H/2ZLTZ1HJl6ex0bpuOAebQxajjImXjcNduhuuiO5TMe3hLueODVzF8kqY 02fTsyp1/mn2FISfrdKg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gG2af-0007t5-UX; Fri, 26 Oct 2018 13:55:54 +0000 Received: from mx2.suse.de ([195.135.220.15] helo=mx1.suse.de) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gG2Tu-0002Wu-H4; Fri, 26 Oct 2018 13:49:22 +0000 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 35833B020; Fri, 26 Oct 2018 13:48:33 +0000 (UTC) From: Nicolas Saenz Julienne To: stefan.wahren@i2se.com, eric@anholt.net, dave.stevenson@raspberrypi.org Subject: [PATCH RFC 06/18] staging: vchiq_arm: rework vchiq_ioc_copy_element_data Date: Fri, 26 Oct 2018 15:48:01 +0200 Message-Id: <20181026134813.7775-7-nsaenzjulienne@suse.de> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181026134813.7775-1-nsaenzjulienne@suse.de> References: <20181026134813.7775-1-nsaenzjulienne@suse.de> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181026_064854_778056_8F4887E0 X-CRM114-Status: GOOD ( 15.76 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devel@driverdev.osuosl.org, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, nsaenzjulienne@suse.de, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP The function is passed to vchiq_core.c for it to go trough all the transfer elements (an array of pointers to data) and copy them into the actual transfer memory (contiguous memory). The logic in the function was "copy an element and return, except when the element is empty, in which case look for the next non-empty element and copy it. The function will be called as many times as necessary until all the elements are copied". Now, this approach already forces the function to loop around elements and felt convoluted, so it was changed to a more straightforward "Copy all the elements into memory as long as they fit". The resulting function is shorter and simpler. Signed-off-by: Nicolas Saenz Julienne --- .../interface/vchiq_arm/vchiq_arm.c | 89 +++++++------------ 1 file changed, 31 insertions(+), 58 deletions(-) diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c index 34160cc3b8bd..1cdfdb714abc 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c @@ -752,74 +752,48 @@ static void close_delivered(USER_SERVICE_T *user_service) } struct vchiq_io_copy_callback_context { - struct vchiq_element *current_element; - size_t current_element_offset; + struct vchiq_element *element; + size_t element_offset; unsigned long elements_to_go; - size_t current_offset; }; -static ssize_t -vchiq_ioc_copy_element_data( - void *context, - void *dest, - size_t offset, - size_t maxsize) +static ssize_t vchiq_ioc_copy_element_data(void *context, void *dest, + size_t offset, size_t maxsize) { - long res; + struct vchiq_io_copy_callback_context *cc = context; + size_t total_bytes_copied = 0; size_t bytes_this_round; - struct vchiq_io_copy_callback_context *copy_context = - (struct vchiq_io_copy_callback_context *)context; - - if (offset != copy_context->current_offset) - return 0; - - if (!copy_context->elements_to_go) - return 0; - - /* - * Complex logic here to handle the case of 0 size elements - * in the middle of the array of elements. - * - * Need to skip over these 0 size elements. - */ - while (1) { - bytes_this_round = min(copy_context->current_element->size - - copy_context->current_element_offset, - maxsize); - - if (bytes_this_round) - break; - copy_context->elements_to_go--; - copy_context->current_element++; - copy_context->current_element_offset = 0; + while (total_bytes_copied < maxsize) { + if (!cc->elements_to_go) + return total_bytes_copied; - if (!copy_context->elements_to_go) - return 0; - } + if (!cc->element->size) { + cc->elements_to_go--; + cc->element++; + cc->element_offset = 0; + continue; + } - res = copy_from_user(dest, - copy_context->current_element->data + - copy_context->current_element_offset, - bytes_this_round); + bytes_this_round = min(cc->element->size - cc->element_offset, + maxsize - total_bytes_copied); - if (res != 0) - return -EFAULT; + if (copy_from_user(dest + total_bytes_copied, + cc->element->data + cc->element_offset, + bytes_this_round)) + return -EFAULT; - copy_context->current_element_offset += bytes_this_round; - copy_context->current_offset += bytes_this_round; + cc->element_offset += bytes_this_round; + total_bytes_copied += bytes_this_round; - /* - * Check if done with current element, and if so advance to the next. - */ - if (copy_context->current_element_offset == - copy_context->current_element->size) { - copy_context->elements_to_go--; - copy_context->current_element++; - copy_context->current_element_offset = 0; + if (cc->element_offset == cc->element->size) { + cc->elements_to_go--; + cc->element++; + cc->element_offset = 0; + } } - return bytes_this_round; + return maxsize; } /************************************************************************** @@ -836,10 +810,9 @@ vchiq_ioc_queue_message(VCHIQ_SERVICE_HANDLE_T handle, unsigned long i; size_t total_size = 0; - context.current_element = elements; - context.current_element_offset = 0; + context.element = elements; + context.element_offset = 0; context.elements_to_go = count; - context.current_offset = 0; for (i = 0; i < count; i++) { if (!elements[i].data && elements[i].size != 0)