From: Stephen Boyd <sboyd@codeaurora.org>
To: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: linux-clk@vger.kernel.org,
Michael Turquette <mturquette@baylibre.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RESEND PATCH v2 12/16] clk: avoid circular clock topology
Date: Mon, 1 Feb 2016 17:08:14 -0800 [thread overview]
Message-ID: <20160202010814.GA4848@codeaurora.org> (raw)
In-Reply-To: <1451298191-30815-13-git-send-email-yamada.masahiro@socionext.com>
On 12/28, Masahiro Yamada wrote:
> Currently, clk_register() never checks a circular parent looping,
> but clock providers could register such an insane clock topology.
> For example, "clk_a" could have "clk_b" as a parent, and vice versa.
> In this case, clk_core_reparent() creates a circular parent list
> and __clk_recalc_accuracies() calls itself recursively forever.
>
> The core infrastructure should be kind enough to bail out, showing
> an appropriate error message in such a case. This helps to easily
> find a bug in clock providers. (uh, I made such a silly mistake
> when I was implementing my clock providers first. I was upset
> because the kernel did not respond, without any error message.)
>
> This commit adds a new helper function, __clk_is_ancestor(). It
> returns true if the second argument is a possible ancestor of the
> first one. If a clock core is a possible ancestor of itself, it
> would make a loop when it were registered. That should be detected
> as an error.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
Applied to clk-next
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2016-02-02 1:08 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-28 10:22 [RESEND PATCH v2 00/16] clk: a collection of various clean-ups and improvements Masahiro Yamada
2015-12-28 10:22 ` [RESEND PATCH v2 01/16] clk: remove unused first argument of __clk_init() Masahiro Yamada
2016-01-08 0:44 ` Vladimir Zapolskiy
2016-01-08 3:56 ` Masahiro Yamada
2016-02-02 1:07 ` Stephen Boyd
2015-12-28 10:22 ` [RESEND PATCH v2 02/16] clk: change the argument of __clk_init() into pointer to clk_core Masahiro Yamada
2016-02-02 1:07 ` Stephen Boyd
2015-12-28 10:22 ` [RESEND PATCH v2 03/16] clk: rename __clk_init() into __clk_core_init() Masahiro Yamada
2016-02-02 1:07 ` Stephen Boyd
2015-12-28 10:22 ` [RESEND PATCH v2 04/16] clk: remove unnecessary !core->parents conditional Masahiro Yamada
2016-02-02 1:07 ` Stephen Boyd
2015-12-28 10:22 ` [RESEND PATCH v2 05/16] clk: change sizeof(struct clk *) to sizeof(*core->parents) Masahiro Yamada
2016-02-02 1:07 ` Stephen Boyd
2015-12-28 10:23 ` [RESEND PATCH v2 06/16] clk: move core->parents allocation to clk_register() Masahiro Yamada
2016-02-02 0:23 ` Stephen Boyd
2016-02-02 1:07 ` Stephen Boyd
2015-12-28 10:23 ` [RESEND PATCH v2 07/16] clk: simplify clk_core_get_parent_by_index() Masahiro Yamada
2016-02-02 1:07 ` Stephen Boyd
2015-12-28 10:23 ` [RESEND PATCH v2 08/16] clk: drop the initial core->parents look-ups from __clk_core_init() Masahiro Yamada
2016-02-02 0:25 ` Stephen Boyd
2016-02-02 1:07 ` Stephen Boyd
2015-12-28 10:23 ` [RESEND PATCH v2 09/16] clk: replace pr_warn() with pr_err() for fatal cases Masahiro Yamada
2016-02-02 1:07 ` Stephen Boyd
2015-12-28 10:23 ` [RESEND PATCH v2 10/16] clk: move checking .git_parent to __clk_core_init() Masahiro Yamada
2016-02-02 0:50 ` Stephen Boyd
2016-02-02 2:19 ` Masahiro Yamada
2016-02-02 2:39 ` Stephen Boyd
2016-02-02 2:48 ` Masahiro Yamada
2016-02-02 20:43 ` Stephen Boyd
2016-02-03 2:09 ` Masahiro Yamada
2016-02-02 1:08 ` Stephen Boyd
2015-12-28 10:23 ` [RESEND PATCH v2 11/16] clk: simplify __clk_init_parent() Masahiro Yamada
2016-02-02 1:08 ` Stephen Boyd
2015-12-28 10:23 ` [RESEND PATCH v2 12/16] clk: avoid circular clock topology Masahiro Yamada
2016-02-02 1:08 ` Stephen Boyd [this message]
2015-12-28 10:23 ` [RESEND PATCH v2 13/16] clk: walk the orphan clock list more simply Masahiro Yamada
2016-02-02 1:08 ` Stephen Boyd
2015-12-28 10:23 ` [RESEND PATCH v2 14/16] clk: make sure parent is not NULL in clk_fetch_parent_index() Masahiro Yamada
2016-02-02 1:08 ` Stephen Boyd
2015-12-28 10:23 ` [RESEND PATCH v2 15/16] clk: simplify clk_fetch_parent_index() function Masahiro Yamada
2016-02-02 1:08 ` Stephen Boyd
2015-12-28 10:23 ` [RESEND PATCH v2 16/16] clk: slightly optimize clk_core_set_parent() Masahiro Yamada
2016-02-02 1:08 ` Stephen Boyd
2016-01-04 23:57 ` [RESEND PATCH v2 00/16] clk: a collection of various clean-ups and improvements Michael Turquette
2016-01-04 23:57 ` Michael Turquette
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