From: Dmitry Vyukov <dvyukov@google.com>
To: akpm@linux-foundation.org, linux-mm@kvack.org
Cc: Dmitry Vyukov <dvyukov@google.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
James Morse <james.morse@arm.com>,
Alexander Popov <alex.popov@linux.com>,
Andrey Konovalov <andreyknvl@google.com>,
linux-kernel@vger.kernel.org, syzkaller@googlegroups.com
Subject: [PATCH] kcov: simplify interrupt check
Date: Tue, 21 Mar 2017 10:10:26 +0100 [thread overview]
Message-ID: <20170321091026.139655-1-dvyukov@google.com> (raw)
in_interrupt() semantics are confusing and wrong for most users
as it also returns true when bh is disabled. Thus we open coded
a proper check for interrupts in __sanitizer_cov_trace_pc()
with a lengthy explanatory comment.
Use the new in_task() predicate instead.
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: James Morse <james.morse@arm.com>
Cc: Alexander Popov <alex.popov@linux.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Cc: syzkaller@googlegroups.com
---
kernel/kcov.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/kernel/kcov.c b/kernel/kcov.c
index 85e5546cd791..cd771993f96f 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -60,15 +60,8 @@ void notrace __sanitizer_cov_trace_pc(void)
/*
* We are interested in code coverage as a function of a syscall inputs,
* so we ignore code executed in interrupts.
- * The checks for whether we are in an interrupt are open-coded, because
- * 1. We can't use in_interrupt() here, since it also returns true
- * when we are inside local_bh_disable() section.
- * 2. We don't want to use (in_irq() | in_serving_softirq() | in_nmi()),
- * since that leads to slower generated code (three separate tests,
- * one for each of the flags).
*/
- if (!t || (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_OFFSET
- | NMI_MASK)))
+ if (!t || !in_task())
return;
mode = READ_ONCE(t->kcov_mode);
if (mode == KCOV_MODE_TRACE) {
--
2.12.1.500.gab5fba24ee-goog
next reply other threads:[~2017-03-21 9:10 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-21 9:10 Dmitry Vyukov [this message]
2017-03-21 9:28 ` [PATCH] kcov: simplify interrupt check Hillf Danton
2017-03-21 9:58 ` Dmitry Vyukov
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