From: Christoph Hellwig <hch@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>,
Christoph Hellwig <hch@lst.de>, Linux MM <linux-mm@kvack.org>,
Jan Kara <jack@suse.cz>, Arnd Bergmann <arnd@arndb.de>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
Linux API <linux-api@vger.kernel.org>,
Andy Lutomirski <luto@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 2/2] mm: introduce MAP_VALIDATE, a mechanism for for safely defining new mmap flags
Date: Fri, 1 Sep 2017 00:34:02 -0700 [thread overview]
Message-ID: <20170901073402.GA19080@infradead.org> (raw)
In-Reply-To: <CA+55aFwsfUj1f41w8hqt9LN3-ajmJ=2AB1Nb6ZzwHgE1OKxGOw@mail.gmail.com>
On Thu, Aug 31, 2017 at 06:27:31PM -0700, Linus Torvalds wrote:
> Why? That's no different from the case statement for the mmu case,
> just written differently.
Yes.
> You *want* existing kernels to fail, since they don't test the bits
> you want to test.
>
> So you just want to rewrite these all as
>
> switch (flags & MAP_TYPE) {
> case MAP_SHARED_VALIDATE:
> .. validate the other bits...
> /* fallhtough */
> case MAP_SHARED:
> .. do the shared case ..
> case MAP_PRIVATE:
> .. do the private case ..
> default:
> return -EINVAL;
> }
Btw, at least my original idea was to make MAP_VALIDATE a flag
instead of another mapping type, that is take it out of MAP_TYPE.
That being said this version is ok with me too - the chances of
needing a new type of private mappings probably isn't too big.
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next prev parent reply other threads:[~2017-09-01 7:34 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-30 23:08 [PATCH 0/2] MAP_VALIDATE and mmap flags validation Dan Williams
2017-08-30 23:08 ` [PATCH 1/2] vfs: add flags parameter to ->mmap() in 'struct file_operations' Dan Williams
2017-08-31 10:02 ` Christoph Hellwig
2017-09-01 0:54 ` Dan Williams
2017-08-30 23:08 ` [PATCH 2/2] mm: introduce MAP_VALIDATE, a mechanism for for safely defining new mmap flags Dan Williams
2017-08-31 10:03 ` Christoph Hellwig
2017-09-01 1:01 ` Dan Williams
2017-09-01 1:27 ` Linus Torvalds
2017-09-01 1:40 ` Dan Williams
2017-09-01 7:34 ` Christoph Hellwig [this message]
2017-08-31 16:49 ` Linus Torvalds
2017-08-31 21:31 ` Dan Williams
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