[v2] of: restore old handling of cells_name=NULL in of_*_phandle_with_args()
diff mbox series

Message ID 20190918084748.hnjkiq7wc5b35wjh@pengutronix.de
State Accepted
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Series
  • [v2] of: restore old handling of cells_name=NULL in of_*_phandle_with_args()
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Context Check Description
robh/checkpatch warning "total: 0 errors, 1 warnings, 55 lines checked"

Commit Message

Uwe Kleine-König Sept. 18, 2019, 8:47 a.m. UTC
Before commit e42ee61017f5 ("of: Let of_for_each_phandle fallback to
non-negative cell_count") the iterator functions calling
of_for_each_phandle assumed a cell count of 0 if cells_name was NULL.
This corner case was missed when implementing the fallback logic in
e42ee61017f5 and resulted in an endless loop.

Restore the old behaviour of of_count_phandle_with_args() and
of_parse_phandle_with_args() and add a check to
of_phandle_iterator_init() to prevent a similar failure as a safety
precaution. of_parse_phandle_with_args_map() doesn't need a similar fix
as cells_name isn't NULL there.

Affected drivers are:
 - drivers/base/power/domain.c
 - drivers/base/power/domain.c
 - drivers/clk/ti/clk-dra7-atl.c
 - drivers/hwmon/ibmpowernv.c
 - drivers/i2c/muxes/i2c-demux-pinctrl.c
 - drivers/iommu/mtk_iommu.c
 - drivers/net/ethernet/freescale/fman/mac.c
 - drivers/opp/of.c
 - drivers/perf/arm_dsu_pmu.c
 - drivers/regulator/of_regulator.c
 - drivers/remoteproc/imx_rproc.c
 - drivers/soc/rockchip/pm_domains.c
 - sound/soc/fsl/imx-audmix.c
 - sound/soc/fsl/imx-audmix.c
 - sound/soc/meson/axg-card.c
 - sound/soc/samsung/tm2_wm5110.c
 - sound/soc/samsung/tm2_wm5110.c

Thanks to Geert Uytterhoeven for reporting the issue, Peter Rosin for
helping pinpoint the actual problem and the testers for confirming this
fix.

Fixes: e42ee61017f5 ("of: Let of_for_each_phandle fallback to non-negative cell_count")
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---

On Wed, Sep 18, 2019 at 08:01:05AM +0000, Peter Rosin wrote:
> On 2019-09-18 08:38, Uwe Kleine-König wrote:
> >  EXPORT_SYMBOL(of_parse_phandle_with_args);
> >  
> > @@ -1765,6 +1779,18 @@ int of_count_phandle_with_args(const struct device_node *np, const char *list_na
> >  	struct of_phandle_iterator it;
> >  	int rc, cur_index = 0;
> >  
> > +	/* If cells_name is NULL we assume a cell count of 0 */
> > +	if (cells_name == NULL) {
> 
> A couple of nits.
> 
> I don't know if there are other considerations, but in the previous two
> hunks you use !cells_name instead of comparing explicitly with NULL.
> Personally, I find the shorter form more readable, and in the name of
> consistency bla bla...

Ack, changed to !cells_name here, too.

> 
> Also, the comment explaining this NULL-check didn't really make sense
> to me until I realized that knowing the cell count to be zero makes
> counting trivial. Something along those lines should perhaps be in the
> comment?

You're right, I extended the comment a bit.
 
> But as I said, these are nits. Feel free to ignore.

I considered resending already anyhow as I fatfingerd my email address.
this is fixed now, too. Additionally I fixed a typo in one of the
comments.

Thanks for your feedback.

Best regards
Uwe

 drivers/of/base.c | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

Comments

Rob Herring Sept. 18, 2019, 8:09 p.m. UTC | #1
On Wed, Sep 18, 2019 at 3:47 AM Uwe Kleine-König
<u.kleine-koenig@pengutronix.de> wrote:
>
> Before commit e42ee61017f5 ("of: Let of_for_each_phandle fallback to
> non-negative cell_count") the iterator functions calling
> of_for_each_phandle assumed a cell count of 0 if cells_name was NULL.
> This corner case was missed when implementing the fallback logic in
> e42ee61017f5 and resulted in an endless loop.
>
> Restore the old behaviour of of_count_phandle_with_args() and
> of_parse_phandle_with_args() and add a check to
> of_phandle_iterator_init() to prevent a similar failure as a safety
> precaution. of_parse_phandle_with_args_map() doesn't need a similar fix
> as cells_name isn't NULL there.
>
> Affected drivers are:
>  - drivers/base/power/domain.c
>  - drivers/base/power/domain.c
>  - drivers/clk/ti/clk-dra7-atl.c
>  - drivers/hwmon/ibmpowernv.c
>  - drivers/i2c/muxes/i2c-demux-pinctrl.c
>  - drivers/iommu/mtk_iommu.c
>  - drivers/net/ethernet/freescale/fman/mac.c
>  - drivers/opp/of.c
>  - drivers/perf/arm_dsu_pmu.c
>  - drivers/regulator/of_regulator.c
>  - drivers/remoteproc/imx_rproc.c
>  - drivers/soc/rockchip/pm_domains.c
>  - sound/soc/fsl/imx-audmix.c
>  - sound/soc/fsl/imx-audmix.c
>  - sound/soc/meson/axg-card.c
>  - sound/soc/samsung/tm2_wm5110.c
>  - sound/soc/samsung/tm2_wm5110.c
>
> Thanks to Geert Uytterhoeven for reporting the issue, Peter Rosin for
> helping pinpoint the actual problem and the testers for confirming this
> fix.
>
> Fixes: e42ee61017f5 ("of: Let of_for_each_phandle fallback to non-negative cell_count")
> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>
> On Wed, Sep 18, 2019 at 08:01:05AM +0000, Peter Rosin wrote:
> > On 2019-09-18 08:38, Uwe Kleine-König wrote:
> > >  EXPORT_SYMBOL(of_parse_phandle_with_args);
> > >
> > > @@ -1765,6 +1779,18 @@ int of_count_phandle_with_args(const struct device_node *np, const char *list_na
> > >     struct of_phandle_iterator it;
> > >     int rc, cur_index = 0;
> > >
> > > +   /* If cells_name is NULL we assume a cell count of 0 */
> > > +   if (cells_name == NULL) {
> >
> > A couple of nits.
> >
> > I don't know if there are other considerations, but in the previous two
> > hunks you use !cells_name instead of comparing explicitly with NULL.
> > Personally, I find the shorter form more readable, and in the name of
> > consistency bla bla...
>
> Ack, changed to !cells_name here, too.
>
> >
> > Also, the comment explaining this NULL-check didn't really make sense
> > to me until I realized that knowing the cell count to be zero makes
> > counting trivial. Something along those lines should perhaps be in the
> > comment?
>
> You're right, I extended the comment a bit.
>
> > But as I said, these are nits. Feel free to ignore.
>
> I considered resending already anyhow as I fatfingerd my email address.
> this is fixed now, too. Additionally I fixed a typo in one of the
> comments.
>
> Thanks for your feedback.
>
> Best regards
> Uwe
>
>  drivers/of/base.c | 35 +++++++++++++++++++++++++++++++++--
>  1 file changed, 33 insertions(+), 2 deletions(-)

Can I get a proper patch please.

Rob
Uwe Kleine-König Sept. 18, 2019, 8:19 p.m. UTC | #2
On Wed, Sep 18, 2019 at 03:09:06PM -0500, Rob Herring wrote:
> On Wed, Sep 18, 2019 at 3:47 AM Uwe Kleine-König
> <u.kleine-koenig@pengutronix.de> wrote:
> >
> > Before commit e42ee61017f5 ("of: Let of_for_each_phandle fallback to
> > non-negative cell_count") the iterator functions calling
> > of_for_each_phandle assumed a cell count of 0 if cells_name was NULL.
> > This corner case was missed when implementing the fallback logic in
> > e42ee61017f5 and resulted in an endless loop.
> >
> > Restore the old behaviour of of_count_phandle_with_args() and
> > of_parse_phandle_with_args() and add a check to
> > of_phandle_iterator_init() to prevent a similar failure as a safety
> > precaution. of_parse_phandle_with_args_map() doesn't need a similar fix
> > as cells_name isn't NULL there.
> >
> > Affected drivers are:
> >  - drivers/base/power/domain.c
> >  - drivers/base/power/domain.c
> >  - drivers/clk/ti/clk-dra7-atl.c
> >  - drivers/hwmon/ibmpowernv.c
> >  - drivers/i2c/muxes/i2c-demux-pinctrl.c
> >  - drivers/iommu/mtk_iommu.c
> >  - drivers/net/ethernet/freescale/fman/mac.c
> >  - drivers/opp/of.c
> >  - drivers/perf/arm_dsu_pmu.c
> >  - drivers/regulator/of_regulator.c
> >  - drivers/remoteproc/imx_rproc.c
> >  - drivers/soc/rockchip/pm_domains.c
> >  - sound/soc/fsl/imx-audmix.c
> >  - sound/soc/fsl/imx-audmix.c
> >  - sound/soc/meson/axg-card.c
> >  - sound/soc/samsung/tm2_wm5110.c
> >  - sound/soc/samsung/tm2_wm5110.c
> >
> > Thanks to Geert Uytterhoeven for reporting the issue, Peter Rosin for
> > helping pinpoint the actual problem and the testers for confirming this
> > fix.
> >
> > Fixes: e42ee61017f5 ("of: Let of_for_each_phandle fallback to non-negative cell_count")
> > Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
> > Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > ---
> >
> > On Wed, Sep 18, 2019 at 08:01:05AM +0000, Peter Rosin wrote:
> > > On 2019-09-18 08:38, Uwe Kleine-König wrote:
> > > >  EXPORT_SYMBOL(of_parse_phandle_with_args);
> > > >
> > > > @@ -1765,6 +1779,18 @@ int of_count_phandle_with_args(const struct device_node *np, const char *list_na
> > > >     struct of_phandle_iterator it;
> > > >     int rc, cur_index = 0;
> > > >
> > > > +   /* If cells_name is NULL we assume a cell count of 0 */
> > > > +   if (cells_name == NULL) {
> > >
> > > A couple of nits.
> > >
> > > I don't know if there are other considerations, but in the previous two
> > > hunks you use !cells_name instead of comparing explicitly with NULL.
> > > Personally, I find the shorter form more readable, and in the name of
> > > consistency bla bla...
> >
> > Ack, changed to !cells_name here, too.
> >
> > >
> > > Also, the comment explaining this NULL-check didn't really make sense
> > > to me until I realized that knowing the cell count to be zero makes
> > > counting trivial. Something along those lines should perhaps be in the
> > > comment?
> >
> > You're right, I extended the comment a bit.
> >
> > > But as I said, these are nits. Feel free to ignore.
> >
> > I considered resending already anyhow as I fatfingerd my email address.
> > this is fixed now, too. Additionally I fixed a typo in one of the
> > comments.
> >
> > Thanks for your feedback.
> >
> > Best regards
> > Uwe
> >
> >  drivers/of/base.c | 35 +++++++++++++++++++++++++++++++++--
> >  1 file changed, 33 insertions(+), 2 deletions(-)
> 
> Can I get a proper patch please.

I don't understand what is wrong with my patch. Can you please expand
what you are missing? I just tried to git-am it and the result looks
fine.

Best regards
Uwe
Uwe Kleine-König Sept. 19, 2019, 6:19 a.m. UTC | #3
On Wed, Sep 18, 2019 at 10:19:54PM +0200, Uwe Kleine-König wrote:
> On Wed, Sep 18, 2019 at 03:09:06PM -0500, Rob Herring wrote:
> > Can I get a proper patch please.
> 
> I don't understand what is wrong with my patch. Can you please expand
> what you are missing? I just tried to git-am it and the result looks
> fine.

I see that the commit this patch is fixing isn't in Linus' tree yet. Do
you want instead of this commit fixing the previous one a single good
patch that replaces e42ee61017f5 ("of: Let of_for_each_phandle fallback
to non-negative cell_count")?

Best regards
Uwe
Rob Herring Sept. 19, 2019, 1:32 p.m. UTC | #4
On Wed, 18 Sep 2019 10:47:48 +0200, Uwe =?iso-8859-1?Q?Kleine-K=F6nig?=          wrote:
> Before commit e42ee61017f5 ("of: Let of_for_each_phandle fallback to
> non-negative cell_count") the iterator functions calling
> of_for_each_phandle assumed a cell count of 0 if cells_name was NULL.
> This corner case was missed when implementing the fallback logic in
> e42ee61017f5 and resulted in an endless loop.
> 
> Restore the old behaviour of of_count_phandle_with_args() and
> of_parse_phandle_with_args() and add a check to
> of_phandle_iterator_init() to prevent a similar failure as a safety
> precaution. of_parse_phandle_with_args_map() doesn't need a similar fix
> as cells_name isn't NULL there.
> 
> Affected drivers are:
>  - drivers/base/power/domain.c
>  - drivers/base/power/domain.c
>  - drivers/clk/ti/clk-dra7-atl.c
>  - drivers/hwmon/ibmpowernv.c
>  - drivers/i2c/muxes/i2c-demux-pinctrl.c
>  - drivers/iommu/mtk_iommu.c
>  - drivers/net/ethernet/freescale/fman/mac.c
>  - drivers/opp/of.c
>  - drivers/perf/arm_dsu_pmu.c
>  - drivers/regulator/of_regulator.c
>  - drivers/remoteproc/imx_rproc.c
>  - drivers/soc/rockchip/pm_domains.c
>  - sound/soc/fsl/imx-audmix.c
>  - sound/soc/fsl/imx-audmix.c
>  - sound/soc/meson/axg-card.c
>  - sound/soc/samsung/tm2_wm5110.c
>  - sound/soc/samsung/tm2_wm5110.c
> 
> Thanks to Geert Uytterhoeven for reporting the issue, Peter Rosin for
> helping pinpoint the actual problem and the testers for confirming this
> fix.
> 
> Fixes: e42ee61017f5 ("of: Let of_for_each_phandle fallback to non-negative cell_count")
> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
> 
> On Wed, Sep 18, 2019 at 08:01:05AM +0000, Peter Rosin wrote:
> > On 2019-09-18 08:38, Uwe Kleine-König wrote:
> > >  EXPORT_SYMBOL(of_parse_phandle_with_args);
> > >  
> > > @@ -1765,6 +1779,18 @@ int of_count_phandle_with_args(const struct device_node *np, const char *list_na
> > >  	struct of_phandle_iterator it;
> > >  	int rc, cur_index = 0;
> > >  
> > > +	/* If cells_name is NULL we assume a cell count of 0 */
> > > +	if (cells_name == NULL) {
> > 
> > A couple of nits.
> > 
> > I don't know if there are other considerations, but in the previous two
> > hunks you use !cells_name instead of comparing explicitly with NULL.
> > Personally, I find the shorter form more readable, and in the name of
> > consistency bla bla...
> 
> Ack, changed to !cells_name here, too.
> 
> > 
> > Also, the comment explaining this NULL-check didn't really make sense
> > to me until I realized that knowing the cell count to be zero makes
> > counting trivial. Something along those lines should perhaps be in the
> > comment?
> 
> You're right, I extended the comment a bit.
>  
> > But as I said, these are nits. Feel free to ignore.
> 
> I considered resending already anyhow as I fatfingerd my email address.
> this is fixed now, too. Additionally I fixed a typo in one of the
> comments.
> 
> Thanks for your feedback.
> 
> Best regards
> Uwe
> 
>  drivers/of/base.c | 35 +++++++++++++++++++++++++++++++++--
>  1 file changed, 33 insertions(+), 2 deletions(-)
> 

Applied, thanks.

Rob

Patch
diff mbox series

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 2f25d2dfecfa..1d667eb730e1 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1286,6 +1286,13 @@  int of_phandle_iterator_init(struct of_phandle_iterator *it,
 
 	memset(it, 0, sizeof(*it));
 
+	/*
+	 * one of cell_count or cells_name must be provided to determine the
+	 * argument length.
+	 */
+	if (cell_count < 0 && !cells_name)
+		return -EINVAL;
+
 	list = of_get_property(np, list_name, &size);
 	if (!list)
 		return -ENOENT;
@@ -1512,10 +1519,17 @@  int of_parse_phandle_with_args(const struct device_node *np, const char *list_na
 				const char *cells_name, int index,
 				struct of_phandle_args *out_args)
 {
+	int cell_count = -1;
+
 	if (index < 0)
 		return -EINVAL;
-	return __of_parse_phandle_with_args(np, list_name, cells_name, -1,
-					    index, out_args);
+
+	/* If cells_name is NULL we assume a cell count of 0 */
+	if (!cells_name)
+		cell_count = 0;
+
+	return __of_parse_phandle_with_args(np, list_name, cells_name,
+					    cell_count, index, out_args);
 }
 EXPORT_SYMBOL(of_parse_phandle_with_args);
 
@@ -1765,6 +1779,23 @@  int of_count_phandle_with_args(const struct device_node *np, const char *list_na
 	struct of_phandle_iterator it;
 	int rc, cur_index = 0;
 
+	/*
+	 * If cells_name is NULL we assume a cell count of 0. This makes
+	 * counting the phandles trivial as each 32bit word in the list is a
+	 * phandle and no arguments are to consider. So we don't iterate through
+	 * the list but just use the length to determine the phandle count.
+	 */
+	if (!cells_name) {
+		const __be32 *list;
+		int size;
+
+		list = of_get_property(np, list_name, &size);
+		if (!list)
+			return -ENOENT;
+
+		return size / sizeof(*list);
+	}
+
 	rc = of_phandle_iterator_init(&it, np, list_name, cells_name, -1);
 	if (rc)
 		return rc;