Merge tag 'core-rseq-2025-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull rseq updates from Thomas Gleixner:
 "Two fixes for RSEQ:

   - Protect the event mask modification against the membarrier() IPI as
     otherwise the RmW operation is unprotected and events might be lost

   - Fix the weak symbol reference in rseq selftests

     The current weak RSEQ symbols definitions which were added to allow
     static linkage are not working correctly as they effectively
     re-define the glibc symbols leading to multiple versions of the
     symbols when compiled with -fno-common.

     Mark them as 'extern' to convert them from weak symbol definitions
     to weak symbol references. That works with static and dynamic
     linkage independent of -fcommon and -fno-common"

* tag 'core-rseq-2025-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rseq/selftests: Use weak symbol reference, not definition, to link with glibc
  rseq: Protect event mask against membarrier IPI

1 files changed, 5 insertions, 5 deletions

diff --git a/kernel/rseq.c b/kernel/rseq.c
index b7a1ec327e81..2452b7366b00 100644
--- a/kernel/rseq.c
+++ b/kernel/rseq.c
@@ -342,12 +342,12 @@ static int rseq_need_restart(struct task_struct *t, u32 cs_flags)
 
 	/*
 	 * Load and clear event mask atomically with respect to
-	 * scheduler preemption.
+	 * scheduler preemption and membarrier IPIs.
 	 */
-	preempt_disable();
-	event_mask = t->rseq_event_mask;
-	t->rseq_event_mask = 0;
-	preempt_enable();
+	scoped_guard(RSEQ_EVENT_GUARD) {
+		event_mask = t->rseq_event_mask;
+		t->rseq_event_mask = 0;
+	}
 
 	return !!event_mask;
 }