Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754016AbeAKFbL (ORCPT + 1 other); Thu, 11 Jan 2018 00:31:11 -0500 Received: from mail-pf0-f196.google.com ([209.85.192.196]:35001 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753749AbeAKFbE (ORCPT ); Thu, 11 Jan 2018 00:31:04 -0500 X-Google-Smtp-Source: ACJfBourn/v7XxK06aiR5Ldb+cBiC/PQCAczSXiew7TR3g+wlNmx35hshSO/H6/cIi0LSu9aZZwirg== From: Eric Biggers To: linux-fsdevel@vger.kernel.org Cc: Alexander Viro , Joe Lawrence , Michael Kerrisk , Willy Tarreau , Mikulas Patocka , "Luis R . Rodriguez" , Kees Cook , linux-kernel@vger.kernel.org, Eric Biggers Subject: [PATCH v2 6/7] pipe: simplify round_pipe_size() Date: Wed, 10 Jan 2018 21:29:01 -0800 Message-Id: <20180111052902.14409-7-ebiggers3@gmail.com> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20180111052902.14409-1-ebiggers3@gmail.com> References: <20180111052902.14409-1-ebiggers3@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Eric Biggers round_pipe_size() calculates the number of pages the requested size corresponds to, then rounds the page count up to the next power of 2. However, it also rounds everything < PAGE_SIZE up to PAGE_SIZE. Therefore, there's no need to actually translate the size into a page count; we just need to round the size up to the next power of 2. We do need to verify the size isn't greater than (1 << 31), since on 32-bit systems roundup_pow_of_two() would be undefined in that case. But that can just be combined with the UINT_MAX check which we need anyway now. Finally, update pipe_set_size() to not redundantly check the return value of round_pipe_size() for the "invalid size" case twice. Signed-off-by: Eric Biggers --- fs/pipe.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/fs/pipe.c b/fs/pipe.c index f1ee1e599495..458f866caf53 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -1022,20 +1022,14 @@ const struct file_operations pipefifo_fops = { */ unsigned int round_pipe_size(unsigned long size) { - unsigned long nr_pages; - - if (size > UINT_MAX) + if (size > (1U << 31)) return 0; /* Minimum pipe size, as required by POSIX */ if (size < PAGE_SIZE) - size = PAGE_SIZE; - - nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; - if (nr_pages == 0) - return 0; + return PAGE_SIZE; - return roundup_pow_of_two(nr_pages) << PAGE_SHIFT; + return roundup_pow_of_two(size); } /* @@ -1050,8 +1044,6 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg) long ret = 0; size = round_pipe_size(arg); - if (size == 0) - return -EINVAL; nr_pages = size >> PAGE_SHIFT; if (!nr_pages) -- 2.15.1