From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relmlor1.renesas.com ([210.160.252.171]:56244 "EHLO relmlie4.idc.renesas.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932571AbdC2BQW (ORCPT ); Tue, 28 Mar 2017 21:16:22 -0400 Message-ID: <87wpb8ansx.wl%kuninori.morimoto.gx@renesas.com> From: Kuninori Morimoto To: Stephen Boyd , Russell King CC: Linux-Kernel , Linux-ALSA , , Linux-Renesas Subject: Question about of_clk_put ? In-Reply-To: <874m2jvtmw.wl%kuninori.morimoto.gx@renesas.com> References: <874m2jvtmw.wl%kuninori.morimoto.gx@renesas.com> MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset="US-ASCII" Date: Wed, 29 Mar 2017 01:16:15 +0000 Sender: linux-clk-owner@vger.kernel.org List-ID: Hi Stephen Now, I'm using devm_get_clk_from_child() (= linux/drivers/clk/clk-devres.c) and I got Oops if I do bind/unbind driver several times. [ 32.008847] Unable to handle kernel paging request at virtual address d503201faa1e03e0 [ 32.017124] pgd = ffff8006f9060000 [ 32.020883] [d503201faa1e03e0] *pgd=0000000000000000 [ 32.026243] Internal error: Oops: 96000004 [#1] PREEMPT SMP [ 32.032198] CPU: 0 PID: 934 Comm: kworker/0:2 Not tainted 4.11.0-rc3+ #1259 [ 32.039573] Hardware name: Renesas Salvator-X board based on r8a7795 (DT) [ 32.046814] Workqueue: events deferred_probe_work_func [ 32.052405] task: ffff8006fad2d800 task.stack: ffff8006f90b8000 [ 32.058809] PC is at __of_clk_get_from_provider+0x174/0x1b0 [ 32.064878] LR is at __of_clk_get_from_provider+0x164/0x1b0 .... [ 32.746677] [] __of_clk_get_from_provider+0x174/0x1b0 [ 32.754131] [] __of_clk_get_by_name+0x104/0x140 [ 32.761058] [] of_clk_get_by_name+0x30/0x50 [ 32.767630] [] devm_get_clk_from_child+0x54/0xb0 ... I tried to find the criminal point, but, I couldn't specify where it is. Sometimes it is NULL pointer access crashed, sometimes it is crashed on of_clk_src_onecell_get(), sometimes there is no Oops. I want to solve this issue, but I want to know about of_clk_put as 1st step. In devm_clk_get() case, it is using clk_get() <-> clk_put() pair, this is OK. In devm_get_clk_from_child() case, it is using of_clk_get_by_name() (= __of_clk_get()) <-> clk_put() pair. If my understand was correct, __of_clk_get() uses __clk_create_clk(), so, its pair should be __clk_free_clk() ? I wonder I can find of_clk_get(), but couldn't find of_clk_put(). Is using of_clk_get() <-> clk_put() OK ? Best regards --- Kuninori Morimoto