From: Evgeniy Polyakov <zbr@ioremap.net>
To: Renata Sayakhova <rsayakhova@gmail.com>
Cc: linux-kernel@vger.kernel.org, greg@kroah.com
Subject: Re: [PATCH] DS2781 Maxim Stand-Alone Fuel Gauge battery and w1 slave drivers
Date: Thu, 1 Mar 2012 02:24:57 +0300 [thread overview]
Message-ID: <20120229232457.GA12803@ioremap.net> (raw)
In-Reply-To: <CAO0_4pY_MXgx1gFRK9ino0P9RAO3e3E00PFCJvjpq2A-6Oz=1Q@mail.gmail.com>
On Thu, Mar 01, 2012 at 12:17:30AM +0100, Renata Sayakhova (rsayakhova@gmail.com) wrote:
> w1_process (w1.c line 982) holds mutex. If during w1_search_process (w1.c
> line 983) slave is found and battery initcall is already done at this
> moment than battery probe() is called. This call leads to
> power_supply_register() and device_add() which does among other things call
> battery properties. battery_get_property() should normally results in
> w1_ds2781_read() and w1_ds2781_io(), but w1_ds2781_io() calls itself
> mutex_lock.
>
> So this weird function is a workaround to avoid a second mutex_lock during
> battery probe(). mutex_holder is set before power_supply_register() and
> unset when probe is done.
>
> This is very brief, if it's not clear I'll try to explain in more details.
> I found this workaround in implementation of ds2780 battery and w1 slave
> drivers.
So basically IO routins caled from ->probe() are already locked so we
protect against deadlock. Ok, I see.
I have no objections, patch looks good
Greg, please pull it into your tree
Thank you
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
--
Evgeniy Polyakov
prev parent reply other threads:[~2012-02-29 23:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-29 13:58 [PATCH 0001] DS2781 Maxim Stand-Alone Fuel Gauge battery and w1 slave drivers Renata Sayakhova
2012-02-29 13:58 ` [PATCH] " Renata Sayakhova
2012-02-29 18:52 ` Evgeniy Polyakov
[not found] ` <CAO0_4pY_MXgx1gFRK9ino0P9RAO3e3E00PFCJvjpq2A-6Oz=1Q@mail.gmail.com>
2012-02-29 23:24 ` Evgeniy Polyakov [this message]
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