From 22036abe17c9f6e295bd9d767312cfb92fc9cf0a Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Mon, 8 Nov 2021 18:35:37 -0800
Subject: [PATCH 4/5] kcov: avoid enable+disable interrupts if !in_task()
Git-commit: 22036abe17c9f6e295bd9d767312cfb92fc9cf0a
Patch-mainline: v5.16-rc1
References: bsc#1189998

kcov_remote_start() may need to allocate memory in the in_task() case
(otherwise per-CPU memory has been pre-allocated) and therefore requires
enabled interrupts.

The interrupts are enabled before checking if the allocation is required
so if no allocation is required then the interrupts are needlessly enabled
and disabled again.

Enable interrupts only if memory allocation is performed.

Link: https://lkml.kernel.org/r/20210923164741.1859522-5-bigeasy@linutronix.de
Link: https://lore.kernel.org/r/20210830172627.267989-5-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Marco Elver <elver@google.com>
Tested-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>

---
 kernel/kcov.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/kcov.c b/kernel/kcov.c
index 4f910231d99a..620dc4ffeb68 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -869,19 +869,19 @@ void kcov_remote_start(u64 handle)
 		size = CONFIG_KCOV_IRQ_AREA_SIZE;
 		area = this_cpu_ptr(&kcov_percpu_data)->irq_area;
 	}
-	spin_unlock_irqrestore(&kcov_remote_lock, flags);
+	spin_unlock(&kcov_remote_lock);
 
 	/* Can only happen when in_task(). */
 	if (!area) {
+		local_irqrestore(flags);
 		area = vmalloc(size * sizeof(unsigned long));
 		if (!area) {
 			kcov_put(kcov);
 			return;
 		}
+		local_irq_save(flags);
 	}
 
-	local_irq_save(flags);
-
 	/* Reset coverage size. */
 	*(u64 *)area = 0;
 
-- 
2.26.2