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Date: Tue, 05 May 2020 15:16:08 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: x86@...nel.org, "Paul E. McKenney" <paulmck@...nel.org>,
Andy Lutomirski <luto@...nel.org>,
Alexandre Chartre <alexandre.chartre@...cle.com>,
Frederic Weisbecker <frederic@...nel.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <sean.j.christopherson@...el.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Petr Mladek <pmladek@...e.com>,
Steven Rostedt <rostedt@...dmis.org>,
Joel Fernandes <joel@...lfernandes.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Juergen Gross <jgross@...e.com>,
Brian Gerst <brgerst@...il.com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Will Deacon <will@...nel.org>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: [patch V4 part 1 06/36] compiler: Simple READ/WRITE_ONCE() implementations
READ/WRITE_ONCE_NOCHECK() is required for atomics in code which cannot be
instrumented like the x86 int3 text poke code. As READ/WRITE_ONCE() is
undergoing a rewrite, provide __{READ,WRITE}_ONCE_SCALAR().
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
include/linux/compiler.h | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -313,6 +313,14 @@ unsigned long read_word_at_a_time(const
__u.__val; \
})
+#define __READ_ONCE_SCALAR(x) \
+ (*(const volatile typeof(x) *)&(x))
+
+#define __WRITE_ONCE_SCALAR(x, val) \
+do { \
+ *(volatile typeof(x) *)&(x) = val; \
+} while (0)
+
/**
* data_race - mark an expression as containing intentional data races
*
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