linux-kernel - Re: [Patch v2 02/15] CIFS: Add support for direct pages in rdata

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f940d126-237c-963f-f64e-e1eb1e8c6c85@talpey.com>
Date:   Tue, 26 Jun 2018 11:13:46 -0400
From:   Tom Talpey <tom@...pey.com>
To:     Jason Gunthorpe <jgg@...pe.ca>
Cc:     longli@...rosoft.com, Steve French <sfrench@...ba.org>,
        linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org,
        linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org
Subject: Re: [Patch v2 02/15] CIFS: Add support for direct pages in rdata

On 6/25/2018 5:01 PM, Jason Gunthorpe wrote:
> On Sat, Jun 23, 2018 at 09:50:20PM -0400, Tom Talpey wrote:
>> On 5/30/2018 3:47 PM, Long Li wrote:
>>> From: Long Li <longli@...rosoft.com>
>>>
>>> Add a function to allocate rdata without allocating pages for data
>>> transfer. This gives the caller an option to pass a number of pages
>>> that point to the data buffer.
>>>
>>> rdata is still reponsible for free those pages after it's done.
>>
>> "Caller" is still responsible? Or is the rdata somehow freeing itself
>> via another mechanism?
>>
>>>
>>> Signed-off-by: Long Li <longli@...rosoft.com>
>>>   fs/cifs/cifsglob.h |  2 +-
>>>   fs/cifs/file.c     | 23 ++++++++++++++++++++---
>>>   2 files changed, 21 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
>>> index 8d16c3e..56864a87 100644
>>> +++ b/fs/cifs/cifsglob.h
>>> @@ -1179,7 +1179,7 @@ struct cifs_readdata {
>>>   	unsigned int			tailsz;
>>>   	unsigned int			credits;
>>>   	unsigned int			nr_pages;
>>> -	struct page			*pages[];
>>> +	struct page			**pages;
>>
>> Technically speaking, these are syntactically equivalent. It may not
>> be worth changing this historic definition.
> 
> [] is a C99 'flex array', it has a different allocation behavior than
> ** and is not interchangeable..

In that case, it's an even better reason to not change the declaration.

Tom.