From: Arnd Bergmann <arnd@arndb.de>
To: David Daney <ddaney@caviumnetworks.com>
Cc: Matt Redfearn <matt.redfearn@imgtec.com>,
ulf.hansson@linaro.org, linux-mmc@vger.kernel.org,
Aleksey Makarov <aleksey.makarov@caviumnetworks.com>,
Chandrakala Chavva <cchavva@caviumnetworks.com>,
David Daney <david.daney@cavium.com>,
Aleksey Makarov <aleksey.makarov@auriga.com>,
Leonid Rosenboim <lrosenboim@caviumnetworks.com>,
Peter Swain <pswain@cavium.com>,
Aaron Williams <aaron.williams@cavium.com>
Subject: Re: [RESEND PATCH v7 2/2] mmc: OCTEON: Add host driver for OCTEON MMC controller
Date: Wed, 20 Apr 2016 02:02:13 +0200 [thread overview]
Message-ID: <5170197.yUbCAn9kNF@wuerfel> (raw)
In-Reply-To: <3904622.mKVlLT0JKv@wuerfel>
On Wednesday 20 April 2016 01:57:08 Arnd Bergmann wrote:
> If you do this
>
> wait_event(&host->wq, !host->current_req);
>
> in the request function as well as
>
> wake_up(&host->wq);
>
> after setting host->current_req to NULL, I think you end up with
> the same level of readability as the semaphore, and slightly
> better object code, and you can drop the 'WARN_ON(host->current_req);'
> which would be known to be impossible.
>
Correction: you would still need some form of serialization to
ensure that only one thread can set the host->current_req
at any time, so it's slightly more complex, either using
a mutex around the wait_event/assignment, or doing
wait_event(&host->wq, !cmpxchg(host->current_req, NULL, mrq));
which probably wants to be encapsulated in an inline function
or annotated with a comment.
Arnd
next prev parent reply other threads:[~2016-04-20 0:02 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-31 15:26 [RESEND PATCH v7 1/2] mmc: OCTEON: Add DT bindings for OCTEON MMC controller Matt Redfearn
2016-03-31 15:26 ` [RESEND PATCH v7 2/2] mmc: OCTEON: Add host driver " Matt Redfearn
2016-04-19 20:46 ` Arnd Bergmann
2016-04-19 21:45 ` David Daney
2016-04-19 22:09 ` Arnd Bergmann
2016-04-19 23:27 ` David Daney
2016-04-19 23:57 ` Arnd Bergmann
2016-04-20 0:02 ` Arnd Bergmann [this message]
2016-04-21 8:02 ` Ulf Hansson
2016-04-21 10:15 ` Arnd Bergmann
2016-04-21 12:44 ` Ulf Hansson
2016-04-21 13:19 ` Arnd Bergmann
2016-04-22 13:54 ` Ulf Hansson
2016-04-22 16:42 ` Arnd Bergmann
2016-04-22 17:49 ` David Daney
2016-04-22 20:23 ` Arnd Bergmann
2016-04-14 12:45 ` [RESEND PATCH v7 1/2] mmc: OCTEON: Add DT bindings " Ulf Hansson
2016-04-18 8:53 ` Matt Redfearn
2016-04-18 11:13 ` Ulf Hansson
2016-04-18 11:37 ` Matt Redfearn
2016-04-18 12:08 ` Ulf Hansson
2016-04-18 12:57 ` Matt Redfearn
2016-04-18 22:59 ` David Daney
2016-04-19 9:15 ` Ulf Hansson
2016-04-19 16:13 ` David Daney
2016-04-19 19:33 ` Ulf Hansson
2016-04-19 20:25 ` David Daney
2016-04-19 20:56 ` Arnd Bergmann
2016-04-19 21:50 ` David Daney
2016-04-20 9:32 ` Ulf Hansson
2016-04-20 22:32 ` David Daney
2016-04-20 22:42 ` Arnd Bergmann
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