Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754120Ab3JBVku (ORCPT ); Wed, 2 Oct 2013 17:40:50 -0400 Received: from mail-pb0-f47.google.com ([209.85.160.47]:44183 "EHLO mail-pb0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753783Ab3JBVks convert rfc822-to-8bit (ORCPT ); Wed, 2 Oct 2013 17:40:48 -0400 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT To: Sylwester Nawrocki , linux@arm.linux.org.uk From: Mike Turquette In-Reply-To: <52420664.2040604@gmail.com> Cc: Sylwester Nawrocki , linux-arm-kernel@lists.infradead.org, jiada_wang@mentor.com, kyungmin.park@samsung.com, myungjoo.ham@samsung.com, t.figa@samsung.com, g.liakhovetski@gmx.de, laurent.pinchart@ideasonboard.com, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, linux-sh@vger.kernel.org References: <1377874402-2944-1-git-send-email-s.nawrocki@samsung.com> <52420664.2040604@gmail.com> Message-ID: <20131002214044.4343.24022@quantum> User-Agent: alot/0.3.4 Subject: Re: [PATCH v6 0/5] clk: clock deregistration support Date: Wed, 02 Oct 2013 14:40:44 -0700 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10372 Lines: 288 Quoting Sylwester Nawrocki (2013-09-24 14:38:44) > On 08/30/2013 04:53 PM, Sylwester Nawrocki wrote: > > This patch series implements clock deregistration in the common clock > > framework. Comparing to v5 it only includes further corrections of NULL > > clock handling. > [...] > > clk: Provide not locked variant of of_clk_get_from_provider() > > clkdev: Fix race condition in clock lookup from device tree > > clk: Add common __clk_get(), __clk_put() implementations > > clk: Assign module owner of a clock being registered > > clk: Implement clk_unregister > > Hi Mike, Russell, > > Would you have any further comments/suggestions on this series ? I don't have any further comments. The changes look good to me and push things in the right direction. I'll wait for Laurent's feedback on the omap3isp driver implications though. Regards, Mike > > I have inspected all callers of clk_register() and all should be fine > with regards to dereferencing dev->driver. The first argument to this > function is either NULL or clk_register() is being called in drivers' > probe() callback, which ensures dev->driver won't change due to holding > dev->mutex. > > The only issue I found might be at the omap3isp driver, which provides > clock to its sub-drivers and takes reference on the sub-driver modules. > When sub-driver calls clk_get() all modules would get locked in memory, > due to circular reference. One solution to that could be to pass NULL > struct device pointer, as in the below patch. > > ---------8<------------------ > From ca5963041aad67e31324cb5d4d5e2cfce1706d4f Mon Sep 17 00:00:00 2001 > From: Sylwester Nawrocki > Date: Thu, 19 Sep 2013 23:52:04 +0200 > Subject: [PATCH] omap3isp: Pass NULL device pointer to clk_register() > > Signed-off-by: Sylwester Nawrocki > --- > drivers/media/platform/omap3isp/isp.c | 15 ++++++++++----- > drivers/media/platform/omap3isp/isp.h | 1 + > 2 files changed, 11 insertions(+), 5 deletions(-) > > diff --git a/drivers/media/platform/omap3isp/isp.c > b/drivers/media/platform/omap3isp/isp.c > index df3a0ec..d7f3c98 100644 > --- a/drivers/media/platform/omap3isp/isp.c > +++ b/drivers/media/platform/omap3isp/isp.c > @@ -290,9 +290,11 @@ static int isp_xclk_init(struct isp_device *isp) > struct clk_init_data init; > unsigned int i; > > + for (i = 0; i < ARRAY_SIZE(isp->xclks); ++i) > + isp->xclks[i] = ERR_PTR(-EINVAL); > + > for (i = 0; i < ARRAY_SIZE(isp->xclks); ++i) { > struct isp_xclk *xclk = &isp->xclks[i]; > - struct clk *clk; > > xclk->isp = isp; > xclk->id = i == 0 ? ISP_XCLK_A : ISP_XCLK_B; > @@ -306,9 +308,9 @@ static int isp_xclk_init(struct isp_device *isp) > > xclk->hw.init = &init; > > - clk = devm_clk_register(isp->dev, &xclk->hw); > - if (IS_ERR(clk)) > - return PTR_ERR(clk); > + xclk->clk = clk_register(NULL, &xclk->hw); > + if (IS_ERR(xclk->clk)) > + return PTR_ERR(xclk->clk); > > if (pdata->xclks[i].con_id == NULL && > pdata->xclks[i].dev_id == NULL) > @@ -320,7 +322,7 @@ static int isp_xclk_init(struct isp_device *isp) > > xclk->lookup->con_id = pdata->xclks[i].con_id; > xclk->lookup->dev_id = pdata->xclks[i].dev_id; > - xclk->lookup->clk = clk; > + xclk->lookup->clk = xclk->clk; > > clkdev_add(xclk->lookup); > } > @@ -335,6 +337,9 @@ static void isp_xclk_cleanup(struct isp_device *isp) > for (i = 0; i < ARRAY_SIZE(isp->xclks); ++i) { > struct isp_xclk *xclk = &isp->xclks[i]; > > + if (!IS_ERR(xclk->clk)) > + clk_unregister(xclk->clk); > + > if (xclk->lookup) > clkdev_drop(xclk->lookup); > } > diff --git a/drivers/media/platform/omap3isp/isp.h > b/drivers/media/platform/omap3isp/isp.h > index cd3eff4..1498f2b 100644 > --- a/drivers/media/platform/omap3isp/isp.h > +++ b/drivers/media/platform/omap3isp/isp.h > @@ -135,6 +135,7 @@ struct isp_xclk { > struct isp_device *isp; > struct clk_hw hw; > struct clk_lookup *lookup; > + struct clk *clk; > enum isp_xclk_id id; > > spinlock_t lock; /* Protects enabled and divider */ > -- > ---------8<------------------ > > > Alternatively an additional argument could be added to the clk_register*() > functions. Something like: > > ---------8<------------------ > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c > index 27f8c42..ef934ac 100644 > --- a/drivers/clk/clk.c > +++ b/drivers/clk/clk.c > @@ -1837,7 +1837,8 @@ struct clk *__clk_register(struct device *dev, > struct clk_hw *hw) > } > EXPORT_SYMBOL_GPL(__clk_register); > > -static int _clk_register(struct device *dev, struct clk_hw *hw, struct > clk *clk) > +static int _clk_register(struct device *dev, struct clk_hw *hw, struct > clk *clk, > + struct module *owner) > { > int i, ret; > > @@ -1877,6 +1878,8 @@ static int _clk_register(struct device *dev, > struct clk_hw *hw, struct clk *clk) > } > } > > + clk->owner = owner; > + > ret = __clk_init(dev, clk); > if (!ret) > return 0; > @@ -1892,7 +1895,7 @@ fail_name: > } > > /** > - * clk_register - allocate a new clock, register it and return an > opaque cookie > + * ___clk_register - allocate a new clock, register it and return an > opaque cookie > * @dev: device that is registering this clock > * @hw: link to hardware-specific clock data > * > @@ -1902,7 +1905,8 @@ fail_name: > * rest of the clock API. In the event of an error clk_register will > return an > * error code; drivers must test for an error code after calling > clk_register. > */ > -struct clk *clk_register(struct device *dev, struct clk_hw *hw) > +struct clk *___clk_register(struct device *dev, struct clk_hw *hw, > + struct module *owner) > { > int ret; > struct clk *clk; > @@ -1914,7 +1918,7 @@ struct clk *clk_register(struct device *dev, > struct clk_hw *hw) > goto fail_out; > } > > - ret = _clk_register(dev, hw, clk); > + ret = _clk_register(dev, hw, clk, owner); > if (!ret) > return clk; > > @@ -1922,7 +1926,7 @@ struct clk *clk_register(struct device *dev, > struct clk_hw *hw) > fail_out: > return ERR_PTR(ret); > } > -EXPORT_SYMBOL_GPL(clk_register); > +EXPORT_SYMBOL_GPL(___clk_register); > > /* > * Free memory allocated for a clock. > @@ -2040,7 +2044,8 @@ static void devm_clk_release(struct device *dev, > void *res) > * automatically clk_unregister()ed on driver detach. See > clk_register() for > * more information. > */ > -struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw) > +struct clk *__devm_clk_register(struct device *dev, struct clk_hw *hw, > + struct module *owner) > { > struct clk *clk; > int ret; > @@ -2049,7 +2054,7 @@ struct clk *devm_clk_register(struct device *dev, > struct clk_hw *hw) > if (!clk) > return ERR_PTR(-ENOMEM); > > - ret = _clk_register(dev, hw, clk); > + ret = _clk_register(dev, hw, clk, owner); > if (!ret) { > devres_add(dev, clk); > } else { > @@ -2059,7 +2064,7 @@ struct clk *devm_clk_register(struct device *dev, > struct clk_hw *hw) > > return clk; > } > -EXPORT_SYMBOL_GPL(devm_clk_register); > +EXPORT_SYMBOL_GPL(__devm_clk_register); > > static int devm_clk_match(struct device *dev, void *res, void *data) > { > diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h > index 13623f3..c656ebf 100644 > --- a/include/linux/clk-provider.h > +++ b/include/linux/clk-provider.h > @@ -31,6 +31,7 @@ > #define CLK_SET_RATE_NO_REPARENT BIT(7) /* don't re-parent on rate > change */ > > struct clk_hw; > +struct module; > > /** > * struct clk_ops - Callback operations for hardware clocks; these are to > @@ -436,8 +437,21 @@ struct clk *clk_register_composite(struct device > *dev, const char *name, > * rest of the clock API. In the event of an error clk_register will > return an > * error code; drivers must test for an error code after calling > clk_register. > */ > -struct clk *clk_register(struct device *dev, struct clk_hw *hw); > -struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw); > +struct clk *___clk_register(struct device *dev, struct clk_hw *hw, > + struct module *owner); > + > +static inline struct clk *clk_register(struct device *dev, struct > clk_hw *hw) > +{ > + return ___clk_register(dev, hw, THIS_MODULE); > +} > + > +struct clk *__devm_clk_register(struct device *dev, struct clk_hw *hw, > + struct module *owner); > +static inline struct clk *devm_clk_register(struct device *dev, > + struct clk_hw *hw) > +{ > + return __devm_clk_register(dev, hw, THIS_MODULE); > +} > > void clk_unregister(struct clk *clk); > void devm_clk_unregister(struct device *dev, struct clk *clk); > > ---------8<------------------ > > Similarly it would need to be done for the remaining clk_register*() > functions, > which have much longer arguments list. > > It's a bit messy, since there is already __clk_register() function with > double > underscore prefix. Perhaps that could be renamed to something else so > all the > functions taking struct module * parameter are prefixed with double > underscore. > > > I would squash patches 3/5 and 4/5 in the next iteration, if it is decided > to keep using dev->driver->owner. > > -- > Thanks, > Sylwester -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/