Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933783AbdDFRIc (ORCPT ); Thu, 6 Apr 2017 13:08:32 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:56134 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932286AbdDFRIZ (ORCPT ); Thu, 6 Apr 2017 13:08:25 -0400 Date: Thu, 6 Apr 2017 19:08:13 +0200 From: Greg KH To: Greg Hackmann Cc: zhangshuxiaomi@gmail.com, arve@android.com, riandrews@android.com, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, zhangshuxiao Subject: Re: [PATCH] staging: android: ashmem: lseek failed due to no FMODE_LSEEK. Message-ID: <20170406170813.GA29139@kroah.com> References: <1491489029-11052-1-git-send-email-zhangshuxiaomi@gmail.com> <94155867-d589-6451-2f3b-a960df559702@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <94155867-d589-6451-2f3b-a960df559702@google.com> User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1656 Lines: 45 On Thu, Apr 06, 2017 at 08:30:40AM -0700, Greg Hackmann wrote: > On 04/06/2017 07:30 AM, zhangshuxiaomi@gmail.com wrote: > > From: zhangshuxiao > > > > vfs_llseek will check whether the file mode has > > FMODE_LSEEK, no return failure. But ashmem can be > > lseek, so add FMODE_LSEEK to ashmem file. > > > > Signed-off-by: Shuxiao Zhang > > Tested-by: Greg Hackmann > > --- > > drivers/staging/android/ashmem.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c > > index 3f11332..e4530ac 100644 > > --- a/drivers/staging/android/ashmem.c > > +++ b/drivers/staging/android/ashmem.c > > @@ -392,6 +392,7 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma) > > ret = PTR_ERR(vmfile); > > goto out; > > } > > + vmfile->f_mode |= FMODE_LSEEK; > > asma->file = vmfile; > > } > > get_file(asma->file); > > > > This commit message is missing some important context. > > ashmem_llseek() passes the llseek() call through to the backing shmem file. > 91360b02ab48 ("ashmem: use vfs_llseek()") changed this from directly calling > the file's llseek() op into a VFS layer call. This also adds a check for > the FMODE_LSEEK bit, so without that bit ashmem_llseek() now always fails > with -ESPIPE. > > I've tested that this patch fixes the regression on both hikey running AOSP > and User Mode Linux running Debian. Thanks for letting me know, I'll update the changelog a bit. How far back does this patch need to go in stable kernel releases? thanks, greg k-h