From: Paul Walmsley <pjw@kernel.org>
Date: Tue, 18 Nov 2025 04:19:27 +0000 (-0700)
Subject: riscv: mm: ptep_get_and_clear(): avoid atomic ops when !CONFIG_SMP
X-Git-Tag: v6.19-rc3~4^2~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=425cc087fbaf267be7683b95481b46a058d63e49;p=thirdparty%2Fkernel%2Fstable.git

riscv: mm: ptep_get_and_clear(): avoid atomic ops when !CONFIG_SMP

When !CONFIG_SMP, there's no need for atomic operations in
ptep_get_and_clear(), so, similar to x86, let's not use atomics in
this case.

Cc: Alexandre Ghiti <alex@ghiti.fr>
Signed-off-by: Paul Walmsley <pjw@kernel.org>
---

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 1df8a6adb407..ebab8ecd78b2 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -660,7 +660,13 @@ extern int ptep_test_and_clear_young(struct vm_area_struct *vma, unsigned long a
 static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
 				       unsigned long address, pte_t *ptep)
 {
+#ifdef CONFIG_SMP
 	pte_t pte = __pte(atomic_long_xchg((atomic_long_t *)ptep, 0));
+#else
+	pte_t pte = *ptep;
+
+	set_pte(ptep, __pte(0));
+#endif
 
 	page_table_check_pte_clear(mm, pte);