Commit 59e9fcf8 authored Sep 18, 2019 by Uwe Kleine-König Committed by Rob Herring Sep 19, 2019

of: restore old handling of cells_name=NULL in of_*_phandle_with_args()



Before commit e42ee610 ("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
e42ee610 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: e42ee610 ("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>
Signed-off-by: Rob Herring <robh@kernel.org>

parent e65e50ff

drivers/of/base.c

+33 −2

Original line number	Diff line number	Diff line
		@@ -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;

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