linux-kernel - [PATCH] x86/efi: mark racy access on efi_rts_work.efi_rts

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Date: Sat, 27 Apr 2024 13:25:07 +0800
From: linke li <lilinke99@...com>
To: 
Cc: xujianhao01@...il.com,
	linke li <lilinke99@...com>,
	Ard Biesheuvel <ardb@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	linux-efi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] x86/efi: mark racy access on efi_rts_work.efi_rts_id

In efi_crash_gracefully_on_page_fault(), efi_rts_work.efi_rts_id can by
changed by other thread from the comment. Mark possible data race on 
efi_rts_work.efi_rts_id as benign using READ_ONCE.

This patch is aimed at reducing the number of benign races reported by
KCSAN in order to focus future debugging effort on harmful races.

Signed-off-by: linke li <lilinke99@...com>
---
 arch/x86/platform/efi/quirks.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index f0cc00032751..4acb81700caf 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -751,7 +751,7 @@ void efi_crash_gracefully_on_page_fault(unsigned long phys_addr)
 	 * because this case occurs *very* rarely and hence could be improved
 	 * on a need by basis.
 	 */
-	if (efi_rts_work.efi_rts_id == EFI_RESET_SYSTEM) {
+	if (READ_ONCE(efi_rts_work.efi_rts_id) == EFI_RESET_SYSTEM) {
 		pr_info("efi_reset_system() buggy! Reboot through BIOS\n");
 		machine_real_restart(MRR_BIOS);
 		return;
-- 
2.39.3 (Apple Git-146)