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SubjectRe: [PATCH 2/2] clk: pmc-atom: use devm_kstrdup_const()
On Mon, Aug 27, 2018 at 02:28:45PM +0200, Bartosz Golaszewski wrote:
> 2018-08-27 12:39 GMT+02:00 Mike Rapoport <rppt@linux.vnet.ibm.com>:
> > On Mon, Aug 27, 2018 at 10:21:01AM +0200, Bartosz Golaszewski wrote:
> >> Use devm_kstrdup_const() in the pmc-atom driver. This mostly serves as
> >> an example of how to use this new routine to shrink driver code.
> >>
> >> While we're at it: replace a call to kcalloc() with devm_kcalloc().
> >>
> >> Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
> >> ---
> >> drivers/clk/x86/clk-pmc-atom.c | 19 ++++---------------
> >> 1 file changed, 4 insertions(+), 15 deletions(-)
> >>
> >> diff --git a/drivers/clk/x86/clk-pmc-atom.c b/drivers/clk/x86/clk-pmc-atom.c
> >> index 08ef69945ffb..daa2192e6568 100644
> >> --- a/drivers/clk/x86/clk-pmc-atom.c
> >> +++ b/drivers/clk/x86/clk-pmc-atom.c
> >> @@ -253,14 +253,6 @@ static void plt_clk_unregister_fixed_rate_loop(struct clk_plt_data *data,
> >> plt_clk_unregister_fixed_rate(data->parents[i]);
> >> }
> >>
> >> -static void plt_clk_free_parent_names_loop(const char **parent_names,
> >> - unsigned int i)
> >> -{
> >> - while (i--)
> >> - kfree_const(parent_names[i]);
> >> - kfree(parent_names);
> >> -}
> >> -
> >> static void plt_clk_unregister_loop(struct clk_plt_data *data,
> >> unsigned int i)
> >> {
> >> @@ -286,8 +278,8 @@ static const char **plt_clk_register_parents(struct platform_device *pdev,
> >> if (!data->parents)
> >> return ERR_PTR(-ENOMEM);
> >>
> >> - parent_names = kcalloc(nparents, sizeof(*parent_names),
> >> - GFP_KERNEL);
> >> + parent_names = devm_kcalloc(&pdev->dev, nparents,
> >> + sizeof(*parent_names), GFP_KERNEL);
> >> if (!parent_names)
> >> return ERR_PTR(-ENOMEM);
> >>
> >> @@ -300,7 +292,8 @@ static const char **plt_clk_register_parents(struct platform_device *pdev,
> >> err = PTR_ERR(data->parents[i]);
> >> goto err_unreg;
> >> }
> >> - parent_names[i] = kstrdup_const(clks[i].name, GFP_KERNEL);
> >> + parent_names[i] = devm_kstrdup_const(&pdev->dev,
> >> + clks[i].name, GFP_KERNEL);
> >> }
> >>
> >> data->nparents = nparents;
> >> @@ -308,7 +301,6 @@ static const char **plt_clk_register_parents(struct platform_device *pdev,
> >>
> >> err_unreg:
> >> plt_clk_unregister_fixed_rate_loop(data, i);
> >> - plt_clk_free_parent_names_loop(parent_names, i);
> >
> > What happens if clks[i].name is not a part of RO data? The devm_kstrdup_const
> > will allocate memory and nothing will ever free it...
> >
>
> I'm looking at it and trying to see if I'm missing something, but
> AFAIK the whole concept of devm_* is to leave out the resource
> management part.
>
> devm_kstrdup_const() will internally call devm_kstrdup() for strings
> that are not in .rodata and once the device is detached, the string
> will be freed (or not if it's in .rodata).

And when it's going to be freed, how the resource management will know
whether it's .rodata or not?

> BR
> Bart
>
> > And, please don't drop kfree(parent_names) here.
> >
> >> return ERR_PTR(err);
> >> }
> >>
> >> @@ -351,15 +343,12 @@ static int plt_clk_probe(struct platform_device *pdev)
> >> goto err_unreg_clk_plt;
> >> }
> >>
> >> - plt_clk_free_parent_names_loop(parent_names, data->nparents);
> >> -
> >> platform_set_drvdata(pdev, data);
> >> return 0;
> >>
> >> err_unreg_clk_plt:
> >> plt_clk_unregister_loop(data, i);
> >> plt_clk_unregister_parents(data);
> >> - plt_clk_free_parent_names_loop(parent_names, data->nparents);
> >
> > Ditto.
> >
> >> return err;
> >> }
> >>
> >> --
> >> 2.18.0
> >>
> >
> > --
> > Sincerely yours,
> > Mike.
> >
>

--
Sincerely yours,
Mike.

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