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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD077C41513 for ; Fri, 11 Aug 2023 07:46:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231279AbjHKHqn (ORCPT ); Fri, 11 Aug 2023 03:46:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58788 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229835AbjHKHqm (ORCPT ); Fri, 11 Aug 2023 03:46:42 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2FB7F1FDD; Fri, 11 Aug 2023 00:46:42 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 74CB0648F4; Fri, 11 Aug 2023 07:46:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3CFF5C433C8; Fri, 11 Aug 2023 07:46:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691740000; bh=GuyoCPl/YJ4xO8sOUZZlYV2+Wm0YbUzDtduIENXUP5Q=; h=Date:From:Subject:To:Cc:References:In-Reply-To:From; b=e1diiZqDkCg25FdOmDG287DkAJgVNNQAff+9luMOhmk0PipbY7RrX5yIwP7buDo/A yrrEVU9hCyH/fScD5LTtvcoRVU+HMPE3DHBMxiNsKTOsGqHhsj1QTRThfkDZiK4MK3 jWhSEXxPrQBu6H3G+KEAaE4gxU2HPyVpHFaf2fjEAu3FoMHdaOzo+Zf45gUa/UwejU zBdCFsmlUUqeJ92Ba5MRwjmYov++aY+MxhEHW4QB188/xnVIckJhm68PyHf/xTdV0K KhbA3TXdbO7n5HQNY9kK3YTgc8Q6YzoI9a0QYgRvGcIC/NGA85aK/sPzYNqvXNmIa1 3F7KBkmymQvAw== Message-ID: <58ea6863-53cd-228b-1474-f67b0bb134f0@kernel.org> Date: Fri, 11 Aug 2023 10:46:34 +0300 MIME-Version: 1.0 From: Georgi Djakov Subject: Re: [PATCH v3 1/3] debugfs: Add write support to debugfs_create_str() To: Mike Tipton , gregkh@linuxfoundation.org, rafael@kernel.org, corbet@lwn.net Cc: linux-pm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, quic_okukatla@quicinc.com, quic_viveka@quicinc.com, peterz@infradead.org, quic_pkondeti@quicinc.com References: <20230807142914.12480-1-quic_mdtipton@quicinc.com> <20230807142914.12480-2-quic_mdtipton@quicinc.com> Content-Language: en-US In-Reply-To: <20230807142914.12480-2-quic_mdtipton@quicinc.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 7.08.23 17:29, Mike Tipton wrote: > Currently, debugfs_create_str() only supports reading strings from > debugfs. Add support for writing them as well. > > Based on original implementation by Peter Zijlstra [0]. Write support > was present in the initial patch version, but dropped in v2 due to lack > of users. We have a user now, so reintroduce it. > > [0] https://lore.kernel.org/all/YF3Hv5zXb%2F6lauzs@hirez.programming.kicks-ass.net/ > Hi Greg, Looks like the original code was reviewed two years ago (not sure if it counts). But in any case, i need an ack from you to apply this. There is no build dependency with the rest of the patches (but there is a functional one). It should be also fine if you apply it directly, if you prefer so? Thanks, Georgi > Signed-off-by: Mike Tipton > --- > fs/debugfs/file.c | 48 +++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 46 insertions(+), 2 deletions(-) > > diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c > index b7711888dd17..87b3753aa4b1 100644 > --- a/fs/debugfs/file.c > +++ b/fs/debugfs/file.c > @@ -904,8 +904,52 @@ EXPORT_SYMBOL_GPL(debugfs_create_str); > static ssize_t debugfs_write_file_str(struct file *file, const char __user *user_buf, > size_t count, loff_t *ppos) > { > - /* This is really only for read-only strings */ > - return -EINVAL; > + struct dentry *dentry = F_DENTRY(file); > + char *old, *new = NULL; > + int pos = *ppos; > + int r; > + > + r = debugfs_file_get(dentry); > + if (unlikely(r)) > + return r; > + > + old = *(char **)file->private_data; > + > + /* only allow strict concatenation */ > + r = -EINVAL; > + if (pos && pos != strlen(old)) > + goto error; > + > + r = -E2BIG; > + if (pos + count + 1 > PAGE_SIZE) > + goto error; > + > + r = -ENOMEM; > + new = kmalloc(pos + count + 1, GFP_KERNEL); > + if (!new) > + goto error; > + > + if (pos) > + memcpy(new, old, pos); > + > + r = -EFAULT; > + if (copy_from_user(new + pos, user_buf, count)) > + goto error; > + > + new[pos + count] = '\0'; > + strim(new); > + > + rcu_assign_pointer(*(char **)file->private_data, new); > + synchronize_rcu(); > + kfree(old); > + > + debugfs_file_put(dentry); > + return count; > + > +error: > + kfree(new); > + debugfs_file_put(dentry); > + return r; > } > > static const struct file_operations fops_str = {