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From: Greg KH <gregkh@linuxfoundation.org>
To: Shuah Khan <skhan@linuxfoundation.org>
Cc: corbet@lwn.net, keescook@chromium.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 01/11] counters: Introduce counter and counter_atomic
Date: Wed, 23 Sep 2020 12:35:17 +0200	[thread overview]
Message-ID: <20200923103517.GJ3154647@kroah.com> (raw)
In-Reply-To: <e57eb89132000b255b5a7952cb82725ec2f3e4e0.1600816121.git.skhan@linuxfoundation.org>

On Tue, Sep 22, 2020 at 07:43:30PM -0600, Shuah Khan wrote:
> Introduce Simple atomic and non-atomic counters.
> 
> There are a number of atomic_t usages in the kernel where atomic_t api
> is used strictly for counting and not for managing object lifetime. In
> some cases, atomic_t might not even be needed.
> 
> The purpose of these counters is twofold: 1. clearly differentiate
> atomic_t counters from atomic_t usages that guard object lifetimes,
> hence prone to overflow and underflow errors. It allows tools that scan
> for underflow and overflow on atomic_t usages to detect overflow and
> underflows to scan just the cases that are prone to errors. 2. provides
> non-atomic counters for cases where atomic isn't necessary.
> 
> Simple atomic and non-atomic counters api provides interfaces for simple
> atomic and non-atomic counters that just count, and don't guard resource
> lifetimes. Counters will wrap around to 0 when it overflows and should
> not be used to guard resource lifetimes, device usage and open counts
> that control state changes, and pm states.
> 
> Using counter_atomic to guard lifetimes could lead to use-after free
> when it overflows and undefined behavior when used to manage state
> changes and device usage/open states.
> 
> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
> ---
>  Documentation/core-api/counters.rst | 158 +++++++++++++
>  MAINTAINERS                         |   7 +
>  include/linux/counters.h            | 343 ++++++++++++++++++++++++++++
>  lib/Kconfig                         |  10 +
>  lib/Makefile                        |   1 +
>  lib/test_counters.c                 | 283 +++++++++++++++++++++++

Tests for new apis, nice!

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

  reply	other threads:[~2020-09-23 10:35 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-23  1:43 [RFC PATCH 00/11] Introduce Simple atomic and non-atomic counters Shuah Khan
2020-09-23  1:43 ` [RFC PATCH 01/11] counters: Introduce counter and counter_atomic Shuah Khan
2020-09-23 10:35   ` Greg KH [this message]
2020-09-23 19:04   ` Kees Cook
2020-09-23 19:34     ` Greg KH
2020-09-23 20:54       ` Kees Cook
2020-09-23 20:48     ` Shuah Khan
2020-09-23 20:58       ` Kees Cook
2020-09-23 21:19         ` Shuah Khan
2020-09-23 22:04           ` Kees Cook
2020-09-23  1:43 ` [RFC PATCH 02/11] selftests:lib: add new test for counters Shuah Khan
2020-09-23  1:43 ` [RFC PATCH 03/11] drivers/base: convert deferred_trigger_count and probe_count to counter_atomic Shuah Khan
2020-09-23 10:30   ` Greg KH
2020-09-23  1:43 ` [RFC PATCH 04/11] drivers/base/devcoredump: convert devcd_count " Shuah Khan
2020-09-23 10:31   ` Greg KH
2020-09-23  1:43 ` [RFC PATCH 05/11] drivers/acpi: convert seqno counter_atomic Shuah Khan
2020-09-24 11:13   ` Rafael J. Wysocki
2020-09-24 15:08     ` Shuah Khan
2020-09-24 15:32       ` Rafael J. Wysocki
2020-09-23  1:43 ` [RFC PATCH 06/11] drivers/acpi/apei: " Shuah Khan
2020-09-23  1:43 ` [RFC PATCH 07/11] drivers/android/binder: convert stats, transaction_log to counter_atomic Shuah Khan
2020-09-23  5:10   ` Greg KH
2020-09-23 19:04     ` Kees Cook
2020-09-23 19:31       ` Greg KH
2020-09-23 20:51         ` Kees Cook
2020-09-23  1:43 ` [RFC PATCH 08/11] drivers/base/test/test_async_driver_probe: convert to use counter_atomic Shuah Khan
2020-09-23 10:33   ` Greg KH
2020-09-23  1:43 ` [RFC PATCH 09/11] drivers/char/ipmi: convert stats " Shuah Khan
2020-09-23  1:43 ` [RFC PATCH 10/11] drivers/misc/vmw_vmci: convert num guest devices counter to counter_atomic Shuah Khan
2020-09-23 10:29   ` Greg KH
2020-09-23  1:43 ` [RFC PATCH 11/11] drivers/edac: convert pci counters " Shuah Khan

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