linux-kernel - [PATCH 3/4] riscv: ptdump: use seq_puts() in pt_dump_seq

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Message-ID: <20251018170451.3355496-1-hi@josie.lol>
Date: Sat, 18 Oct 2025 19:04:51 +0200
From: Josephine Pfeiffer <hi@...ie.lol>
To: paul.walmsley@...ive.com,
	palmer@...belt.com,
	aou@...s.berkeley.edu
Cc: alex@...ti.fr,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 3/4] riscv: ptdump: use seq_puts() in pt_dump_seq_puts() macro

The pt_dump_seq_puts() macro incorrectly uses seq_printf() instead of
seq_puts(). This is both a performance issue and conceptually wrong,
as the macro name suggests plain string output (puts) but the
implementation uses formatted output (printf).

The macro is used in ptdump.c:301 to output a newline character. Using
seq_printf() adds unnecessary overhead for format string parsing when
outputting this constant string.

This bug was introduced in commit 59c4da8640cc ("riscv: Add support to
dump the kernel page tables") in 2020, which copied the implementation
pattern from other architectures that had the same bug.

Fixes: 59c4da8640cc ("riscv: Add support to dump the kernel page tables")
Signed-off-by: Josephine Pfeiffer <hi@...ie.lol>
---
 arch/riscv/mm/ptdump.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/mm/ptdump.c b/arch/riscv/mm/ptdump.c
index 3b51690cc876..34299c2b231f 100644
--- a/arch/riscv/mm/ptdump.c
+++ b/arch/riscv/mm/ptdump.c
@@ -21,7 +21,7 @@
 #define pt_dump_seq_puts(m, fmt)	\
 ({					\
 	if (m)				\
-		seq_printf(m, fmt);	\
+		seq_puts(m, fmt);	\
 })

 /*
-- 
2.51.1.dirty