From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Laight Date: Sat, 11 Dec 2021 17:53:46 +0000 Subject: RE: [PATCH v2 0/2] kdump: simplify code Message-Id: <0c5cb37139af4f3e85cc2c5115d7d006@AcuMS.aculab.com> List-Id: References: <1639193588-7027-1-git-send-email-yangtiezhu@loongson.cn> In-Reply-To: <1639193588-7027-1-git-send-email-yangtiezhu@loongson.cn> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: 'Tiezhu Yang' , Dave Young , Baoquan He , Vivek Goyal , Andrew Morton Cc: "linux-arm-kernel@lists.infradead.org" , "linux-ia64@vger.kernel.org" , "linux-mips@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-riscv@lists.infradead.org" , "linux-sh@vger.kernel.org" , "x86@kernel.org" , "linux-fsdevel@vger.kernel.org" , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Xuefeng Li From: Tiezhu Yang > Sent: 11 December 2021 03:33 > > v2: > -- add copy_to_user_or_kernel() in lib/usercopy.c > -- define userbuf as bool type Instead of having a flag to indicate whether the buffer is user or kernel, would it be better to have two separate buffer pointers. One for a user space buffer, the other for a kernel space buffer. Exactly one of the buffers should always be NULL. That way the flag is never incorrectly set. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)