[PATCH 18/28] LoongArch: Refactor bootcmdline_init() to use seq_buf instead of strlcat()

bootcmdline_init() uses multiple strlcat() calls to append
init_command_line or CONFIG_CMDLINE to boot_command_line.

In preparation for removing the deprecated strlcat() API[1], initialize a
struct seq_buf with the existing contents of boot_command_line and use
seq_buf_puts() to append the command line fragments.

Link: https://github.com/KSPP/linux/issues/370 [1]
Cc: codemender-patching+linux@google.com
Assisted-by: CoPilot:1.0 [shell_command_run, editor_update_file, make_kernel_build_single_file]
Signed-off-by: Bill Wendling <morbo@google.com>
---
Cc: Russell King <linux@armlinux.org.uk>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@gmail.com>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Matthias Schwarzott <zzam@gentoo.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Tony Nguyen <anthony.l.nguyen@intel.com>
Cc: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Arend van Spriel <arend.vanspriel@broadcom.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Saravana Kannan <saravanak@kernel.org>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Cc: Peter Griffin <peter.griffin@linaro.org>
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Cc: Linus Walleij <linusw@kernel.org>
Cc: Anil Gurumurthy <anil.gurumurthy@qlogic.com>
Cc: Sudarsana Kalluru <sudarsana.kalluru@qlogic.com>
Cc: "Martin K. Petersen" <mkp@kernel.org>
Cc: Trond Myklebust <trondmy@kernel.org>
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Cc: Dai Ngo <Dai.Ngo@oracle.com>
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Cc: Bill Wendling <morbo@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
Cc: Kanglong Wang <redacted>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Qiang Ma <redacted>
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Cc: Pengpeng Hou <redacted>
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Cc: Breno Leitao <leitao@debian.org>
Cc: Thorsten Blum <blum@kernel.org>
Cc: Harshit Mogalapalli <redacted>
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Cc: Lyude Paul <lyude@redhat.com>
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Cc: Imre Deak <redacted>
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Cc: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Cc: Alexander Stein <redacted>
Cc: Cryolitia PukNgae <cryolitia@uniontech.com>
Cc: Jiaming Zhang <redacted>
Cc: Will Porter <redacted>
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---
 arch/loongarch/kernel/setup.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 6fa4a22a58fd..826396f141b9 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c

@@ -33,6 +33,7 @@
 #include <linux/of_address.h>
 #include <linux/suspend.h>
 #include <linux/swiotlb.h>
+#include <linux/seq_buf.h>
 
 #include <asm/addrspace.h>
 #include <asm/alternative.h>

@@ -305,6 +306,8 @@ static void __init fdt_setup(void)
 
 static void __init bootcmdline_init(char **cmdline_p)
 {
+	struct seq_buf s;
+
 	/*
 	 * If CONFIG_CMDLINE_FORCE is enabled then initializing the command line
 	 * is trivial - we simply use the built-in command line unconditionally &

@@ -315,6 +318,11 @@ static void __init bootcmdline_init(char **cmdline_p)
 		goto out;
 	}
 
+	/* Initialize seq_buf pointing to boot_command_line */
+	s.buffer = boot_command_line;
+	s.size = COMMAND_LINE_SIZE;
+	s.len = strlen(boot_command_line);
+
 #ifdef CONFIG_OF_FLATTREE
 	/*
 	 * If CONFIG_CMDLINE_BOOTLOADER is enabled and we are in FDT-based system,

@@ -323,11 +331,11 @@ static void __init bootcmdline_init(char **cmdline_p)
 	 * to boot_command_line.
 	 */
 	if (initial_boot_params) {
-		if (boot_command_line[0])
-			strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
+		if (s.len)
+			seq_buf_puts(&s, " ");
 
-		if (!strstr(boot_command_line, init_command_line))
-			strlcat(boot_command_line, init_command_line, COMMAND_LINE_SIZE);
+		if (!strstr(s.buffer, init_command_line))
+			seq_buf_puts(&s, init_command_line);
 
 		goto out;
 	}

@@ -338,14 +346,14 @@ static void __init bootcmdline_init(char **cmdline_p)
 	 * CONFIG_CMDLINE_EXTEND is enabled.
 	 */
 	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) && CONFIG_CMDLINE[0]) {
-		strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
-		strlcat(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
+		seq_buf_puts(&s, " ");
+		seq_buf_puts(&s, CONFIG_CMDLINE);
 	}
 
 	/*
 	 * Use built-in command line if the bootloader command line is empty.
 	 */
-	if (IS_ENABLED(CONFIG_CMDLINE_BOOTLOADER) && !boot_command_line[0])
+	if (IS_ENABLED(CONFIG_CMDLINE_BOOTLOADER) && !s.len)
 		strscpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
 
 out:

-- 
2.55.0.1032.g73a4cd73de-goog