From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ralf Baechle Date: Fri, 08 Apr 2016 10:06:00 +0000 Subject: Re: [PATCH v2] clk: let clk_disable() return immediately if clk is NULL or error Message-Id: <20160408100600.GI1668@linux-mips.org> List-Id: References: <1459821083-28116-1-git-send-email-yamada.masahiro@socionext.com> <20160408003328.GA14441@codeaurora.org> In-Reply-To: <20160408003328.GA14441@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org On Thu, Apr 07, 2016 at 05:33:28PM -0700, Stephen Boyd wrote: > On 04/05, Masahiro Yamada wrote: > > The clk_disable() in the common clock framework (drivers/clk/clk.c) > > returns immediately if a given clk is NULL or an error pointer. It > > allows clock consumers to call clk_disable() without IS_ERR_OR_NULL > > checking if drivers are only used with the common clock framework. > > > > Unfortunately, NULL/error checking is missing from some of non-common > > clk_disable() implementations. This prevents us from completely > > dropping NULL/error checking from callers. Let's make it tree-wide > > consistent by adding IS_ERR_OR_NULL(clk) to all callees. > > > > Signed-off-by: Masahiro Yamada > > Acked-by: Greg Ungerer > > Acked-by: Wan Zongshun > > --- > > > > Stephen, > > > > This patch has been unapplied for a long time. > > > > Please let me know if there is something wrong with this patch. > > > > I'm mostly confused why we wouldn't want to encourage people to > call clk_disable or unprepare on a clk that's an error pointer. > Typically an error pointer should be dealt with, instead of > silently ignored, so why wasn't it dealt with by passing it up > the probe() path? While your argument makes perfect sense, Many clk_disable implementations are already doing similar checks, for example: arch/arm/mach-davinci/clock.c: void clk_disable(struct clk *clk) { unsigned long flags; if (clk = NULL || IS_ERR(clk)) return; [...] arch/arm/mach-omap1/clock.c void clk_disable(struct clk *clk) { unsigned long flags; if (clk = NULL || IS_ERR(clk)) return; [...] arch/avr32/mach-at32ap/clock.c void clk_disable(struct clk *clk) { unsigned long flags; if (IS_ERR_OR_NULL(clk)) return; [...] arch/mips/lantiq/clk.c: static inline int clk_good(struct clk *clk) { return clk && !IS_ERR(clk); } [...] void clk_disable(struct clk *clk) { if (unlikely(!clk_good(clk))) return; if (clk->disable) [...] So should we go and weed out these checks? Ralf