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From: Ilya Dryomov <idryomov@gmail.com>
To: David Howells <dhowells@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	nicolas.dichtel@6wind.com, raven@themaw.net,
	Christian Brauner <christian@brauner.io>,
	keyrings@vger.kernel.org, linux-usb@vger.kernel.org,
	linux-block <linux-block@vger.kernel.org>,
	linux-security-module@vger.kernel.org,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-api@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 04/10] pipe: Use head and tail pointers for the ring, not cursor and length [ver #2]
Date: Thu, 31 Oct 2019 16:57:53 +0100	[thread overview]
Message-ID: <CAOi1vP9GAmy5NXJisrDssspoRcc+UHum+cyBsJTMNTjz_jieoQ@mail.gmail.com> (raw)
In-Reply-To: <16620.1572534687@warthog.procyon.org.uk>

On Thu, Oct 31, 2019 at 4:11 PM David Howells <dhowells@redhat.com> wrote:
>
> How about:
>
>  * We use head and tail indices that aren't masked off, except at the
>  * point of dereference, but rather they're allowed to wrap naturally.
>  * This means there isn't a dead spot in the buffer, provided the ring
>  * size is a power of two and <= 2^31.

To me "provided" reads like this thing works without a dead spot or
with a dead spot, depending on whether the condition is met.  I would
say:

>  * This means there isn't a dead spot in the buffer, but the ring
>  * size has to be a power of two and <= 2^31.

Thanks,

                Ilya

WARNING: multiple messages have this Message-ID (diff)
From: Ilya Dryomov <idryomov@gmail.com>
To: David Howells <dhowells@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	nicolas.dichtel@6wind.com, raven@themaw.net,
	Christian Brauner <christian@brauner.io>,
	keyrings@vger.kernel.org, linux-usb@vger.kernel.org,
	linux-block <linux-block@vger.kernel.org>,
	linux-security-module@vger.kernel.org,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-api@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 04/10] pipe: Use head and tail pointers for the ring, not cursor and length [ver #2]
Date: Thu, 31 Oct 2019 15:57:53 +0000	[thread overview]
Message-ID: <CAOi1vP9GAmy5NXJisrDssspoRcc+UHum+cyBsJTMNTjz_jieoQ@mail.gmail.com> (raw)
In-Reply-To: <16620.1572534687@warthog.procyon.org.uk>

On Thu, Oct 31, 2019 at 4:11 PM David Howells <dhowells@redhat.com> wrote:
>
> How about:
>
>  * We use head and tail indices that aren't masked off, except at the
>  * point of dereference, but rather they're allowed to wrap naturally.
>  * This means there isn't a dead spot in the buffer, provided the ring
>  * size is a power of two and <= 2^31.

To me "provided" reads like this thing works without a dead spot or
with a dead spot, depending on whether the condition is met.  I would
say:

>  * This means there isn't a dead spot in the buffer, but the ring
>  * size has to be a power of two and <= 2^31.

Thanks,

                Ilya

  reply	other threads:[~2019-10-31 15:57 UTC|newest]

Thread overview: 111+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-23 20:17 [RFC PATCH 00/10] pipe: Notification queue preparation [ver #2] David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:17 ` [RFC PATCH 01/10] pipe: Reduce #inclusion of pipe_fs_i.h " David Howells
2019-10-23 20:17   ` David Howells
2019-10-23 20:17   ` David Howells
2019-10-23 20:17 ` [RFC PATCH 02/10] Remove the nr_exclusive argument from __wake_up_sync_key() " David Howells
2019-10-23 20:17   ` David Howells
2019-10-23 20:17   ` David Howells
2019-10-23 20:17 ` [RFC PATCH 03/10] Add wake_up_interruptible_sync_poll_locked() " David Howells
2019-10-23 20:17   ` David Howells
2019-10-23 20:17   ` David Howells
2019-10-23 20:17 ` [RFC PATCH 04/10] pipe: Use head and tail pointers for the ring, not cursor and length " David Howells
2019-10-23 20:17   ` David Howells
2019-10-23 20:17   ` David Howells
2019-10-26  0:29   ` kbuild test robot
2019-10-26  0:50   ` kbuild test robot
2019-10-26 14:58   ` [pipe] 6567a02d20: BUG:kernel_NULL_pointer_dereference,address kernel test robot
2019-10-26 14:58     ` kernel test robot
2019-10-26 14:58     ` kernel test robot
2019-10-27 14:03   ` [RFC PATCH 04/10] pipe: Use head and tail pointers for the ring, not cursor and length [ver #2] Linus Torvalds
2019-10-27 14:03     ` Linus Torvalds
2019-10-30 16:19   ` Ilya Dryomov
2019-10-30 16:19     ` Ilya Dryomov
2019-10-30 20:35     ` Rasmus Villemoes
2019-10-30 20:35       ` Rasmus Villemoes
2019-10-30 22:16       ` Ilya Dryomov
2019-10-30 22:16         ` Ilya Dryomov
2019-10-30 22:38         ` Rasmus Villemoes
2019-10-30 22:38           ` Rasmus Villemoes
2019-10-31 15:11     ` David Howells
2019-10-31 15:57       ` Ilya Dryomov [this message]
2019-10-31 15:57         ` Ilya Dryomov
2019-11-01 14:53       ` David Howells
2019-10-31 14:57   ` David Howells
2019-11-03 11:17     ` Matthew Wilcox
2019-11-03 11:17       ` Matthew Wilcox
2019-12-06 21:47   ` Johannes Hirte
2019-12-06 21:47     ` Johannes Hirte
2019-12-06 22:14     ` Linus Torvalds
2019-12-06 22:14       ` Linus Torvalds
2019-12-07  0:00       ` Johannes Hirte
2019-12-07  0:00         ` Johannes Hirte
2019-12-07  1:03         ` Linus Torvalds
2019-12-07  1:03           ` Linus Torvalds
2019-12-08 17:56           ` Johannes Hirte
2019-12-08 17:56             ` Johannes Hirte
2019-12-08 18:10             ` Linus Torvalds
2019-12-08 18:10               ` Linus Torvalds
2019-12-07  6:47         ` Linus Torvalds
2019-12-07  6:47           ` Linus Torvalds
2019-12-06 22:15   ` David Howells
2019-10-23 20:17 ` [RFC PATCH 05/10] pipe: Allow pipes to have kernel-reserved slots " David Howells
2019-10-23 20:17   ` David Howells
2019-10-23 20:17   ` David Howells
2019-10-23 20:18 ` [RFC PATCH 06/10] pipe: Advance tail pointer inside of wait spinlock in pipe_read() " David Howells
2019-10-23 20:18   ` David Howells
2019-10-23 20:18   ` David Howells
2019-10-23 20:18 ` [RFC PATCH 07/10] pipe: Conditionalise wakeup " David Howells
2019-10-23 20:18   ` David Howells
2019-10-23 20:18   ` David Howells
2019-10-27 15:57   ` Konstantin Khlebnikov
2019-10-27 15:57     ` Konstantin Khlebnikov
2019-10-31 15:21   ` David Howells
2019-10-31 16:38   ` David Howells
2019-11-03 11:04     ` Konstantin Khlebnikov
2019-11-03 11:04       ` Konstantin Khlebnikov
2019-10-23 20:18 ` [RFC PATCH 08/10] pipe: Rearrange sequence in pipe_write() to preallocate slot " David Howells
2019-10-23 20:18   ` David Howells
2019-10-23 20:18   ` David Howells
2019-10-23 20:18 ` [RFC PATCH 09/10] pipe: Remove redundant wakeup from pipe_write() " David Howells
2019-10-23 20:18   ` David Howells
2019-10-23 20:18   ` David Howells
2019-10-23 20:18 ` [RFC PATCH 10/10] pipe: Check for ring full inside of the spinlock in " David Howells
2019-10-23 20:18   ` David Howells
2019-10-23 20:18   ` David Howells
2019-10-24 10:32 ` [RFC PATCH 04/10] pipe: Use head and tail pointers for the ring, not cursor and length " David Howells
2019-10-24 10:32   ` David Howells
2019-10-24 13:14 ` [RFC PATCH 00/10] pipe: Notification queue preparation " Peter Zijlstra
2019-10-24 13:14   ` Peter Zijlstra
2019-10-24 16:57 ` [RFC PATCH 11/10] pipe: Add fsync() support " David Howells
2019-10-24 16:57   ` David Howells
2019-10-24 21:29   ` Linus Torvalds
2019-10-24 21:29     ` Linus Torvalds
2019-10-25  8:34   ` David Howells
2019-10-25  8:34     ` David Howells
2019-10-27 15:22   ` Christoph Hellwig
2019-10-27 15:22     ` Christoph Hellwig
2019-10-27 16:04   ` Konstantin Khlebnikov
2019-10-27 16:04     ` Konstantin Khlebnikov
2019-10-31 15:13   ` David Howells
2019-10-31 15:15   ` David Howells
2019-11-02 18:53     ` Linus Torvalds
2019-11-02 18:53       ` Linus Torvalds
2019-11-02 19:34     ` David Howells
2019-11-02 20:31       ` Andy Lutomirski
2019-11-02 20:31         ` Andy Lutomirski
2019-11-02 22:03         ` Linus Torvalds
2019-11-02 22:03           ` Linus Torvalds
2019-11-02 22:09           ` Linus Torvalds
2019-11-02 22:09             ` Linus Torvalds
2019-11-02 22:30           ` Andy Lutomirski
2019-11-02 22:30             ` Andy Lutomirski
2019-11-02 23:02             ` Linus Torvalds
2019-11-02 23:02               ` Linus Torvalds
2019-11-02 23:09               ` Linus Torvalds
2019-11-02 23:09                 ` Linus Torvalds
2019-11-02 23:14                 ` Andy Lutomirski
2019-11-02 23:14                   ` Andy Lutomirski
2019-11-03 12:02                   ` Konstantin Khlebnikov
2019-11-03 12:02                     ` Konstantin Khlebnikov

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