71 lines
2.3 KiB
Plaintext
71 lines
2.3 KiB
Plaintext
|
From abe76789f8e7ce61b357f693eaed5b28feab5ce2 Mon Sep 17 00:00:00 2001
|
||
|
|
From: Hollis Blanchard <hollis_blanchard@mentor.com>
|
||
|
|
Date: Mon, 13 Aug 2018 12:11:33 -0700
|
||
|
|
Subject: [PATCH] Fix build break around __atomic_*() with GCC<4.7
|
||
|
|
|
||
|
|
The __atomic_* GCC primitives were introduced in GCC 4.7, but Red Hat
|
||
|
|
Enterprise Linux 6.x (for example) provides GCC 4.4. Tweak the current code to
|
||
|
|
use the (most conservative) __sync_synchronize() primitive provided by those
|
||
|
|
older GCC versions.
|
||
|
|
|
||
|
|
(Really, no __atomic or __sync operations are needed here at all, since POSIX
|
||
|
|
4.12 "Memory Synchronization" says pthread_mutex_lock() and
|
||
|
|
pthread_mutex_unlock() "synchronize memory with respect to other threads"...)
|
||
|
|
|
||
|
|
Signed-off-by: Hollis Blanchard <hollis_blanchard@mentor.com>
|
||
|
|
---
|
||
|
|
libselinux/src/label_file.h | 18 ++++++++++++++++++
|
||
|
|
1 file changed, 18 insertions(+)
|
||
|
|
|
||
|
|
diff --git a/libselinux/src/label_file.h b/libselinux/src/label_file.h
|
||
|
|
index 2fa85474..47859baf 100644
|
||
|
|
--- a/libselinux/src/label_file.h
|
||
|
|
+++ b/libselinux/src/label_file.h
|
||
|
|
@@ -351,8 +351,14 @@ static inline int compile_regex(struct saved_data *data, struct spec *spec,
|
||
|
|
* init_routine does not take a parameter, it's not possible
|
||
|
|
* to use, so we generate the same effect with atomics and a
|
||
|
|
* mutex */
|
||
|
|
+#ifdef __ATOMIC_RELAXED
|
||
|
|
regex_compiled =
|
||
|
|
__atomic_load_n(&spec->regex_compiled, __ATOMIC_ACQUIRE);
|
||
|
|
+#else
|
||
|
|
+ /* GCC <4.7 */
|
||
|
|
+ __sync_synchronize();
|
||
|
|
+ regex_compiled = spec->regex_compiled;
|
||
|
|
+#endif
|
||
|
|
if (regex_compiled) {
|
||
|
|
return 0; /* already done */
|
||
|
|
}
|
||
|
|
@@ -360,8 +366,14 @@ static inline int compile_regex(struct saved_data *data, struct spec *spec,
|
||
|
|
__pthread_mutex_lock(&spec->regex_lock);
|
||
|
|
/* Check if another thread compiled the regex while we waited
|
||
|
|
* on the mutex */
|
||
|
|
+#ifdef __ATOMIC_RELAXED
|
||
|
|
regex_compiled =
|
||
|
|
__atomic_load_n(&spec->regex_compiled, __ATOMIC_ACQUIRE);
|
||
|
|
+#else
|
||
|
|
+ /* GCC <4.7 */
|
||
|
|
+ __sync_synchronize();
|
||
|
|
+ regex_compiled = spec->regex_compiled;
|
||
|
|
+#endif
|
||
|
|
if (regex_compiled) {
|
||
|
|
__pthread_mutex_unlock(&spec->regex_lock);
|
||
|
|
return 0;
|
||
|
|
@@ -404,7 +416,13 @@ static inline int compile_regex(struct saved_data *data, struct spec *spec,
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Done. */
|
||
|
|
+#ifdef __ATOMIC_RELAXED
|
||
|
|
__atomic_store_n(&spec->regex_compiled, true, __ATOMIC_RELEASE);
|
||
|
|
+#else
|
||
|
|
+ /* GCC <4.7 */
|
||
|
|
+ spec->regex_compiled = true;
|
||
|
|
+ __sync_synchronize();
|
||
|
|
+#endif
|
||
|
|
__pthread_mutex_unlock(&spec->regex_lock);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
--
|
||
|
|
2.13.0
|
||
|
|
|