54 lines
2.2 KiB
Diff
54 lines
2.2 KiB
Diff
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From 2e359284497c361e3208501fc70d49b2c54dc4ef Mon Sep 17 00:00:00 2001
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From: Michael Jeanson <mjeanson@efficios.com>
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Date: Tue, 14 Sep 2021 10:41:08 -0400
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Subject: [PATCH] Always use '__thread' for Thread local storage except on MSVC
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Use the GCC extension '__thread' [1] for Thread local storage on all C
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and C++ compilers except MSVC.
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While C11 and C++11 respectively offer '_Thread_local' and
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'thread_local' as potentialy faster implementations, they offer no
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guarantees of compatibility when used in a library interface which might
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be used by both C and C++ client code.
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[1] https://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html
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Change-Id: If4fe8bcdbda24b21dedf382112bd5c5f836c00c8
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Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
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Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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[Retrieved from:
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https://github.com/urcu/userspace-rcu/commit/2e359284497c361e3208501fc70d49b2c54dc4ef]
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Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
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---
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include/urcu/tls-compat.h | 15 +++++++--------
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1 file changed, 7 insertions(+), 8 deletions(-)
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diff --git a/include/urcu/tls-compat.h b/include/urcu/tls-compat.h
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index 25cf375a..a2c94ded 100644
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--- a/include/urcu/tls-compat.h
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+++ b/include/urcu/tls-compat.h
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@@ -35,15 +35,14 @@ extern "C" {
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#ifdef CONFIG_RCU_TLS
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/*
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- * Don't use C++ 'thread_local' on MacOs, the implementation is incompatible
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- * with C and will result in a link error when accessing an extern variable
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- * provided by the C library from C++ code.
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+ * Default to '__thread' on all C and C++ compilers except MSVC. While C11 has
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+ * '_Thread_local' and C++11 has 'thread_local', only '__thread' seems to have
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+ * a compatible implementation when linking public extern symbols across
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+ * language boundaries.
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+ *
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+ * For more details, see 'https://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html'.
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*/
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-#if defined (__cplusplus) && (__cplusplus >= 201103L) && !defined(__APPLE__)
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-# define URCU_TLS_STORAGE_CLASS thread_local
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-#elif defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L)
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-# define URCU_TLS_STORAGE_CLASS _Thread_local
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-#elif defined (_MSC_VER)
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+#if defined(_MSC_VER)
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# define URCU_TLS_STORAGE_CLASS __declspec(thread)
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#else
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# define URCU_TLS_STORAGE_CLASS __thread
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