On Tue, Mar 20, 2012 at 7:32 PM, Saravana Kannan <skannan@xxxxxxxxxxxxxx> wrote: > On 03/20/2012 05:13 PM, Turquette, Mike wrote: >> >> On Tue, Mar 20, 2012 at 12:46 AM, Saravana Kannan >> <skannan@xxxxxxxxxxxxxx> 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<skannan@xxxxxxxxxxxxxx> >>>>> Cc: Mike Turquette<mturquette@xxxxxxxxxx> >>>>> Cc: Andrew Lunn<andrew@xxxxxxx> >>>>> Cc: Rob Herring<rob.herring@xxxxxxxxxxx> >>>>> Cc: Russell King<linux@xxxxxxxxxxxxxxxx> >>>>> Cc: Jeremy Kerr<jeremy.kerr@xxxxxxxxxxxxx> >>>>> Cc: Thomas Gleixner<tglx@xxxxxxxxxxxxx> >>>>> Cc: Arnd Bergman<arnd.bergmann@xxxxxxxxxx> >>>>> Cc: Paul Walmsley<paul@xxxxxxxxx> >>>>> Cc: Shawn Guo<shawn.guo@xxxxxxxxxxxxx> >>>>> Cc: Sascha Hauer<s.hauer@xxxxxxxxxxxxxx> >>>>> Cc: Jamie Iles<jamie@xxxxxxxxxxxxx> >>>>> Cc: Richard Zhao<richard.zhao@xxxxxxxxxx> >>>>> Cc: Saravana Kannan<skannan@xxxxxxxxxxxxxx> >>>>> Cc: Magnus Damm<magnus.damm@xxxxxxxxx> >>>>> Cc: Mark Brown<broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx> >>>>> Cc: Linus Walleij<linus.walleij@xxxxxxxxxxxxxx> >>>>> Cc: Stephen Boyd<sboyd@xxxxxxxxxxxxxx> >>>>> Cc: Amit Kucheria<amit.kucheria@xxxxxxxxxx> >>>>> Cc: Deepak Saxena<dsaxena@xxxxxxxxxx> >>>>> Cc: Grant Likely<grant.likely@xxxxxxxxxxxx> >>>>> --- >>>>> 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. > > > No problem, go for it. > > >> >>> 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... > > > The last discussion I remember, NULL was considered a valid clock. So, I > think on error, we shouldn't ever return NULL when the return type is struct > clk *. IIRC, that discussion was with respect to the .parent member of struct clk. It was decided that having .parent = NULL does not imply that a clock is a root clock, but instead we rely on the CLK_IS_ROOT flag. I can't think of any other instance where a NULL clk when returned from a registration function would be useful. Regards, Mike > Thanks, > Saravana -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
