linux-kernel - [PATCH 4.9 53/95] clk: fix false-positive Wmaybe-uninitialized warning

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Message-Id: <20180422135212.582894376@linuxfoundation.org>
Date:   Sun, 22 Apr 2018 15:53:22 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
        Arnd Bergmann <arnd@...db.de>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Stephen Boyd <sboyd@...nel.org>
Subject: [PATCH 4.9 53/95] clk: fix false-positive Wmaybe-uninitialized warning

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arnd Bergmann <arnd@...db.de>

commit ce33f284935e08229046b30635e6aadcbab02b53 upstream.

When we build this driver with on x86-32, gcc produces a false-positive warning:

drivers/clk/renesas/clk-sh73a0.c: In function 'sh73a0_cpg_clocks_init':
drivers/clk/renesas/clk-sh73a0.c:155:10: error: 'parent_name' may be used uninitialized in this function [-Werror=maybe-uninitialized]
   return clk_register_fixed_factor(NULL, name, parent_name, 0,

We can work around that warning by adding a fake initialization, I tried
and failed to come up with any better workaround. This is currently one
of few remaining warnings for a 4.14.y randconfig build, so it would be
good to also have it backported at least to that version. Older versions
have more randconfig warnings, so we might not care.

I had not noticed this earlier, because one patch in my randconfig test
tree removes the '-ffreestanding' option on x86-32, and that avoids
the warning. The -ffreestanding flag was originally global but moved
into arch/i386 by Andi Kleen in commit 6edfba1b33c7 ("[PATCH] x86_64:
Don't define string functions to builtin") as a 'temporary workaround'.

Like many temporary hacks, this turned out to be rather long-lived, from
all I can tell we still need a simple fix to asm/string_32.h before it
can be removed, but I'm not sure about how to best do that.

Cc: stable@...r.kernel.org
Cc: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Acked-by: Geert Uytterhoeven <geert+renesas@...der.be>
Signed-off-by: Stephen Boyd <sboyd@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/clk/renesas/clk-sh73a0.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/clk/renesas/clk-sh73a0.c
+++ b/drivers/clk/renesas/clk-sh73a0.c
@@ -46,7 +46,7 @@ struct div4_clk {
 	unsigned int shift;
 };

-static struct div4_clk div4_clks[] = {
+static const struct div4_clk div4_clks[] = {
 	{ "zg", "pll0", CPG_FRQCRA, 16 },
 	{ "m3", "pll1", CPG_FRQCRA, 12 },
 	{ "b",  "pll1", CPG_FRQCRA,  8 },
@@ -79,7 +79,7 @@ sh73a0_cpg_register_clock(struct device_
 {
 	const struct clk_div_table *table = NULL;
 	unsigned int shift, reg, width;
-	const char *parent_name;
+	const char *parent_name = NULL;
 	unsigned int mult = 1;
 	unsigned int div = 1;

@@ -135,7 +135,7 @@ sh73a0_cpg_register_clock(struct device_
 		shift = 24;
 		width = 5;
 	} else {
-		struct div4_clk *c;
+		const struct div4_clk *c;

 		for (c = div4_clks; c->name; c++) {
 			if (!strcmp(name, c->name)) {