From: Linus Torvalds <torvalds@linux-foundation.org>
To: Cedric Blancher <cedric.blancher@gmail.com>
Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Konstantin Khlebnikov <koct9i@gmail.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Matthew Wilcox <mawilcox@microsoft.com>
Subject: Re: [PATCH 2/2] radix-tree: Fix optimisation problem
Date: Sat, 24 Sep 2016 17:18:28 -0700 [thread overview]
Message-ID: <CA+55aFyRG=us-EKnomo=QPE0GR1Qdxyw1Ozmuzw0EJcSr7U3hQ@mail.gmail.com> (raw)
In-Reply-To: <CALXu0Ucx-6PeEk9nTD-4nZvwyVr9LLXcFGFzhctX-ucKfCygGA@mail.gmail.com>
On Sat, Sep 24, 2016 at 4:35 PM, Cedric Blancher
<cedric.blancher@gmail.com> wrote:
>>
>> void *entry = parent->slots[offset];
>> int siboff = entry - parent->slots;
>
> If entry is a pointer to void, how can you do pointer arithmetic with it?
It's actually void **.
(That said, gcc has an extension that considers "void *" to be a byte
pointer, so you can actually do arithmetic on them, and it acts like
"char *")
> Also, if you use pointer distances, the use of int is not valid, it
> should then be ptrdiff_t siboff.
The use of "int" is perfectly valid, since it's limited by
RADIX_TREE_MAP_SIZE, so it's going to be a small integer.
Linus
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next prev parent reply other threads:[~2016-09-25 0:18 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-22 18:53 [PATCH 0/2] Fix radix_tree_lookup_slot() Matthew Wilcox
2016-09-22 18:53 ` [PATCH 1/2] radix tree test suite: Test radix_tree_replace_slot() for multiorder entries Matthew Wilcox
2016-09-22 18:53 ` [PATCH 2/2] radix-tree: Fix optimisation problem Matthew Wilcox
2016-09-22 18:09 ` Linus Torvalds
2016-09-23 20:16 ` Matthew Wilcox
2016-09-24 20:21 ` Linus Torvalds
2016-09-24 20:47 ` Linus Torvalds
2016-09-24 21:04 ` Kirill A. Shutemov
2016-09-24 22:54 ` Linus Torvalds
2016-09-26 4:26 ` Ross Zwisler
2016-09-24 8:36 ` Konstantin Khlebnikov
2016-09-24 23:35 ` Cedric Blancher
2016-09-25 0:18 ` Linus Torvalds [this message]
2016-09-25 17:59 ` Cedric Blancher
2016-09-25 18:04 ` Linus Torvalds
2016-09-25 19:04 ` Linus Torvalds
2016-09-25 19:40 ` Cedric Blancher
2016-09-25 19:56 ` Linus Torvalds
2016-09-26 21:28 ` Matthew Wilcox
2016-09-26 21:48 ` Cedric Blancher
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