Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   John Ogness <john.ogness@linutronix.de>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc:     linux-kernel@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>,
        Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrea Parri <andrea.parri@amarulasolutions.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Brendan Higgins <brendanhiggins@google.com>,
        kexec@lists.infradead.org
Subject: Re: [RFC PATCH v5 1/3] printk-rb: new printk ringbuffer implementation (writer)
References: <20191128015235.12940-1-john.ogness@linutronix.de>
        <20191128015235.12940-2-john.ogness@linutronix.de>
        <20191209074249.GC88619@google.com>
Date:   Mon, 09 Dec 2019 10:00:57 +0100
In-Reply-To: <20191209074249.GC88619@google.com> (Sergey Senozhatsky's message
        of "Mon, 9 Dec 2019 16:42:50 +0900")
Message-ID: <87v9qpzxdi.fsf@linutronix.de>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.4 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 2019-12-09, Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> wrote:
>> +#define _DATA_SIZE(sz_bits)		(1UL << (sz_bits))
>> +#define _DESCS_COUNT(ct_bits)		(1U << (ct_bits))
>> +#define DESC_SV_BITS			(sizeof(int) * 8)
>> +#define DESC_COMMITTED_MASK		(1U << (DESC_SV_BITS - 1))
>
> What does SV state for? State Value?

Yes. Originally this thing was just called the state. But it was a bit
confusing in the code because there is also an enum desc_state (used for
state queries), which is _not_ the value that is stored in the state
variable. That's why the code is using state_var/state_val (SV) for the
actual data values, keeping it separate from desc_state/d_state for the
the state queries.

John Ogness