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Mon, 12 Oct 2020 14:39:31 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 052EAA405F; Mon, 12 Oct 2020 14:39:31 +0000 (GMT) Received: from [9.145.9.103] (unknown [9.145.9.103]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 12 Oct 2020 14:39:30 +0000 (GMT) Subject: Re: [PATCH v2 08/17] s390/pci: Remove races against pte updates To: DRI Development , LKML , kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, linux-s390@vger.kernel.org, Gerald Schaefer , Daniel Vetter , Jason Gunthorpe , Dan Williams , Kees Cook , Andrew Morton , John Hubbard , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jan Kara References: <20201009075934.3509076-1-daniel.vetter@ffwll.ch> <20201009075934.3509076-9-daniel.vetter@ffwll.ch> <6deb08dd-46f3-bf26-5362-fdc696f6fd74@linux.ibm.com> <20201012141906.GX438822@phenom.ffwll.local> From: Niklas Schnelle Message-ID: <3c28a96a-6bb5-f581-4671-5c87161238f7@linux.ibm.com> Date: Mon, 12 Oct 2020 16:39:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201012141906.GX438822@phenom.ffwll.local> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-10-12_12:2020-10-12,2020-10-12 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 lowpriorityscore=0 impostorscore=0 spamscore=0 malwarescore=0 adultscore=0 mlxlogscore=999 mlxscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010120117 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org ... snip ... >>> Cc: linux-media@vger.kernel.org >>> Cc: Niklas Schnelle >>> Cc: Gerald Schaefer >>> Cc: linux-s390@vger.kernel.org >>> -- >>> v2: Move VM_IO | VM_PFNMAP checks around so they keep returning EINVAL >>> like before (Gerard) >> >> I think the above should go before the CC/Signed-off/Reviewev block. > > This is a per-subsystem bikeshed :-) drivers/gpu definitely wants it > above, but most core subsystems want it below. I'll move it. Today I learned, thanks! That said I think most of the time I've actually not seen version change information in the commit message itself only in the cover letters. I really don't care just looked odd to me. > >>> --- >>> arch/s390/pci/pci_mmio.c | 98 +++++++++++++++++++++++----------------- >>> 1 file changed, 57 insertions(+), 41 deletions(-) >>> >>> diff --git a/arch/s390/pci/pci_mmio.c b/arch/s390/pci/pci_mmio.c >>> index 401cf670a243..1a6adbc68ee8 100644 >>> --- a/arch/s390/pci/pci_mmio.c >>> +++ b/arch/s390/pci/pci_mmio.c >>> @@ -119,33 +119,15 @@ static inline int __memcpy_toio_inuser(void __iomem *dst, >>> return rc; >>> } >>> >>> -static long get_pfn(unsigned long user_addr, unsigned long access, >>> - unsigned long *pfn) >>> -{ >>> - struct vm_area_struct *vma; >>> - long ret; >>> - >>> - mmap_read_lock(current->mm); >>> - ret = -EINVAL; >>> - vma = find_vma(current->mm, user_addr); >>> - if (!vma) >>> - goto out; >>> - ret = -EACCES; >>> - if (!(vma->vm_flags & access)) >>> - goto out; >>> - ret = follow_pfn(vma, user_addr, pfn); >>> -out: >>> - mmap_read_unlock(current->mm); >>> - return ret; >>> -} >>> - >>> SYSCALL_DEFINE3(s390_pci_mmio_write, unsigned long, mmio_addr, >>> const void __user *, user_buffer, size_t, length) >>> { >>> u8 local_buf[64]; >>> void __iomem *io_addr; >>> void *buf; >>> - unsigned long pfn; >>> + struct vm_area_struct *vma; >>> + pte_t *ptep; >>> + spinlock_t *ptl; >> >> With checkpatch.pl --strict the above yields a complained >> "CHECK: spinlock_t definition without comment" but I think >> that's really okay since your commit description is very clear. >> Same oin line 277. > > I think this is a falls positive, checkpatch doesn't realize that > SYSCALL_DEFINE3 is a function, not a structure. And in a structure I'd > have added the kerneldoc or comment. Interesting, your theory sounds convincing, I too thought this was a bit too pedantic. > > I'll fix up all the nits you've found for the next round. Thanks for > taking a look. You're welcome hope I didn't sound pedantic. I think you've a lot more experience actually and this can indeed turn into bikeshedding but since I was answering anyway and most of this was checkpatch… > -Daniel >