From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Turquette, Mike" Subject: Re: [PATCH 1/2] clk: Fix error handling in fixed clock hardware type register fn Date: Tue, 20 Mar 2012 17:13:08 -0700 Message-ID: References: <1332214706-675-1-git-send-email-skannan@codeaurora.org> <20120320071957.GH3852@pengutronix.de> <348585ed29fb3ff171267c03658e6c0d.squirrel@www.codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from na3sys009aog114.obsmtp.com ([74.125.149.211]:44266 "EHLO na3sys009aog114.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755572Ab2CUANe convert rfc822-to-8bit (ORCPT ); Tue, 20 Mar 2012 20:13:34 -0400 Received: by eeke50 with SMTP id e50so187614eek.10 for ; Tue, 20 Mar 2012 17:13:31 -0700 (PDT) In-Reply-To: <348585ed29fb3ff171267c03658e6c0d.squirrel@www.codeaurora.org> Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: Saravana Kannan Cc: Sascha Hauer , Andrew Lunn , Grant Likely , Jamie Iles , Jeremy Kerr , Magnus Damm , Deepak Saxena , linux-arm-kernel@lists.infradead.org, Arnd Bergman , linux-arm-msm@vger.kernel.org, Rob Herring , Russell King , Thomas Gleixner , Richard Zhao , Shawn Guo , Paul Walmsley , Linus Walleij , Mark Brown , Stephen Boyd , linux-kernel@vger.kernel.org, Amit Kucheria On Tue, Mar 20, 2012 at 12:46 AM, Saravana Kannan wrote: > On Tue, March 20, 2012 12:19 am, Sascha Hauer wrote: >> On Mon, Mar 19, 2012 at 08:38:25PM -0700, Saravana Kannan wrote: >>> If memory allocation for the parents array or the parent string fai= ls, >>> then >>> fail the registration immediately instead of calling clk_register a= nd >>> hoping it fails there. >>> >>> Return -ENOMEM on failure. >>> >>> Signed-off-by: Saravana Kannan >>> Cc: Mike Turquette >>> Cc: Andrew Lunn >>> Cc: Rob Herring >>> Cc: Russell King >>> Cc: Jeremy Kerr >>> Cc: Thomas Gleixner >>> Cc: Arnd Bergman >>> Cc: Paul Walmsley >>> Cc: Shawn Guo >>> Cc: Sascha Hauer >>> Cc: Jamie Iles >>> Cc: Richard Zhao >>> Cc: Saravana Kannan >>> Cc: Magnus Damm >>> Cc: Mark Brown >>> Cc: Linus Walleij >>> Cc: Stephen Boyd >>> Cc: Amit Kucheria >>> Cc: Deepak Saxena >>> Cc: Grant Likely >>> --- >>> There are still some memory free issues when clk_register() fails, = but I >>> will >>> fix it when I fixed the other register() fns to return ENOMEM of al= loc >>> failure instead of a NULL. >>> >>> =A0drivers/clk/clk-fixed-rate.c | =A0 10 +++++++--- >>> =A01 files changed, 7 insertions(+), 3 deletions(-) >>> >>> diff --git a/drivers/clk/clk-fixed-rate.c b/drivers/clk/clk-fixed-r= ate.c >>> index 90c79fb..6423ae9 100644 >>> --- a/drivers/clk/clk-fixed-rate.c >>> +++ b/drivers/clk/clk-fixed-rate.c >>> @@ -61,22 +61,26 @@ struct clk *clk_register_fixed_rate(struct devi= ce >>> *dev, const char *name, >>> =A0 =A0 =A0 =A0 =A0 =A0 =A0parent_names =3D kmalloc(sizeof(char *),= GFP_KERNEL); >>> >>> =A0 =A0 =A0 =A0 =A0 =A0 =A0if (! parent_names) >>> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0goto out; >>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0goto fail_ptr; >>> >>> =A0 =A0 =A0 =A0 =A0 =A0 =A0len =3D sizeof(char) * strlen(parent_nam= e); >>> >>> =A0 =A0 =A0 =A0 =A0 =A0 =A0parent_names[0] =3D kmalloc(len, GFP_KER= NEL); >>> >>> =A0 =A0 =A0 =A0 =A0 =A0 =A0if (!parent_names[0]) >>> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0goto out; >>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0goto fail_str; >>> >>> =A0 =A0 =A0 =A0 =A0 =A0 =A0strncpy(parent_names[0], parent_name, le= n); >>> =A0 =A0 =A0} >> >> It's easier to add a char *parent to struct clk_fixed and pass it to >> clk_register with &fixed->parent. This saves you a kmalloc call and >> makes the error path simpler. It's the same way already done in the >> divider. I thought I had done this for v7... hmm looks like one got left out. I'll line up a patch to get it in sync with the others as part of my fixes. > I thought about that since I saw the same was done for gated and divi= der > (I think). Here is my guess at Mike's reasoning for this: > > Gated and divider clocks have to have a parent. There's nothing to ga= te > otherwise. But fixed rate clocks might not have a parent. It could be= XO's > or PLLs running off of always on XOs not controlled by the SoC. So, i= t's > arguable to not have a parent. I don't have a strong opinion on this = -- > since Mike took the time to write it, it left it to his subjective > preference. I appreciate the thoughtfulness. Re-using the same type of mechanism as the divider and gate clocks will still allow the fixed-rate clock to be parentless, and it makes for cleaner code, one less allocation and lines up with how the other single-parent basic clocks are done, so I'll take that method in instead of your patch. > I sent this patch first since it was around the place I was cleaning = up. I > didn't want to actually just shuffle around a bug. As I mentioned, th= is > patch still leaves a bug open -- what if clk_register() fails. I plan= to > fix that once my two patches are picked up (hopefully). Do you still find it useful to return -ENOMEM from the registration function instead of a NULL clock? I'm always worried that people don't check for error codes on pointers in their platform code and only check for NULL... Regards, Mike > Thanks, > Saravana From mboxrd@z Thu Jan 1 00:00:00 1970 From: mturquette@ti.com (Turquette, Mike) Date: Tue, 20 Mar 2012 17:13:08 -0700 Subject: [PATCH 1/2] clk: Fix error handling in fixed clock hardware type register fn In-Reply-To: <348585ed29fb3ff171267c03658e6c0d.squirrel@www.codeaurora.org> References: <1332214706-675-1-git-send-email-skannan@codeaurora.org> <20120320071957.GH3852@pengutronix.de> <348585ed29fb3ff171267c03658e6c0d.squirrel@www.codeaurora.org> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Mar 20, 2012 at 12:46 AM, Saravana Kannan wrote: > On Tue, March 20, 2012 12:19 am, Sascha Hauer wrote: >> On Mon, Mar 19, 2012 at 08:38:25PM -0700, Saravana Kannan wrote: >>> If memory allocation for the parents array or the parent string fails, >>> then >>> fail the registration immediately instead of calling clk_register and >>> hoping it fails there. >>> >>> Return -ENOMEM on failure. >>> >>> Signed-off-by: Saravana Kannan >>> Cc: Mike Turquette >>> Cc: Andrew Lunn >>> Cc: Rob Herring >>> Cc: Russell King >>> Cc: Jeremy Kerr >>> Cc: Thomas Gleixner >>> Cc: Arnd Bergman >>> Cc: Paul Walmsley >>> Cc: Shawn Guo >>> Cc: Sascha Hauer >>> Cc: Jamie Iles >>> Cc: Richard Zhao >>> Cc: Saravana Kannan >>> Cc: Magnus Damm >>> Cc: Mark Brown >>> Cc: Linus Walleij >>> Cc: Stephen Boyd >>> Cc: Amit Kucheria >>> Cc: Deepak Saxena >>> Cc: Grant Likely >>> --- >>> There are still some memory free issues when clk_register() fails, but I >>> will >>> fix it when I fixed the other register() fns to return ENOMEM of alloc >>> failure instead of a NULL. >>> >>> ?drivers/clk/clk-fixed-rate.c | ? 10 +++++++--- >>> ?1 files changed, 7 insertions(+), 3 deletions(-) >>> >>> diff --git a/drivers/clk/clk-fixed-rate.c b/drivers/clk/clk-fixed-rate.c >>> index 90c79fb..6423ae9 100644 >>> --- a/drivers/clk/clk-fixed-rate.c >>> +++ b/drivers/clk/clk-fixed-rate.c >>> @@ -61,22 +61,26 @@ struct clk *clk_register_fixed_rate(struct device >>> *dev, const char *name, >>> ? ? ? ? ? ? ?parent_names = kmalloc(sizeof(char *), GFP_KERNEL); >>> >>> ? ? ? ? ? ? ?if (! parent_names) >>> - ? ? ? ? ? ? ? ? ? ?goto out; >>> + ? ? ? ? ? ? ? ? ? ?goto fail_ptr; >>> >>> ? ? ? ? ? ? ?len = sizeof(char) * strlen(parent_name); >>> >>> ? ? ? ? ? ? ?parent_names[0] = kmalloc(len, GFP_KERNEL); >>> >>> ? ? ? ? ? ? ?if (!parent_names[0]) >>> - ? ? ? ? ? ? ? ? ? ?goto out; >>> + ? ? ? ? ? ? ? ? ? ?goto fail_str; >>> >>> ? ? ? ? ? ? ?strncpy(parent_names[0], parent_name, len); >>> ? ? ?} >> >> It's easier to add a char *parent to struct clk_fixed and pass it to >> clk_register with &fixed->parent. This saves you a kmalloc call and >> makes the error path simpler. It's the same way already done in the >> divider. I thought I had done this for v7... hmm looks like one got left out. I'll line up a patch to get it in sync with the others as part of my fixes. > I thought about that since I saw the same was done for gated and divider > (I think). Here is my guess at Mike's reasoning for this: > > Gated and divider clocks have to have a parent. There's nothing to gate > otherwise. But fixed rate clocks might not have a parent. It could be XO's > or PLLs running off of always on XOs not controlled by the SoC. So, it's > arguable to not have a parent. I don't have a strong opinion on this -- > since Mike took the time to write it, it left it to his subjective > preference. I appreciate the thoughtfulness. Re-using the same type of mechanism as the divider and gate clocks will still allow the fixed-rate clock to be parentless, and it makes for cleaner code, one less allocation and lines up with how the other single-parent basic clocks are done, so I'll take that method in instead of your patch. > I sent this patch first since it was around the place I was cleaning up. I > didn't want to actually just shuffle around a bug. As I mentioned, this > patch still leaves a bug open -- what if clk_register() fails. I plan to > fix that once my two patches are picked up (hopefully). Do you still find it useful to return -ENOMEM from the registration function instead of a NULL clock? I'm always worried that people don't check for error codes on pointers in their platform code and only check for NULL... Regards, Mike > Thanks, > Saravana