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authorFrederic Weisbecker <fweisbec@gmail.com>2016-03-24 15:38:01 +0100
committerIngo Molnar <mingo@kernel.org>2016-03-29 11:52:11 +0200
commit5529578a27288d11d4d15635c258c6dde0f0fb10 (patch)
tree5cbd7b8d522cd07c0afc0f57b34d77fa7e12516a /kernel
parentf009a7a767e792d5ab0b46c08d46236ea5271dd9 (diff)
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locking/atomic, sched: Unexport fetch_or()
This patch functionally reverts: 5fd7a09cfb8c ("atomic: Export fetch_or()") During the merge Linus observed that the generic version of fetch_or() was messy: " This makes the ugly "fetch_or()" macro that the scheduler used internally a new generic helper, and does a bad job at it. " e23604edac2a Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Now that we have introduced atomic_fetch_or(), fetch_or() is only used by the scheduler in order to deal with thread_info flags which type can vary across architectures. Lets confine fetch_or() back to the scheduler so that we encourage future users to use the more robust and well typed atomic_t version instead. While at it, fetch_or() gets robustified, pasting improvements from a previous patch by Ingo Molnar that avoids needless expression re-evaluations in the loop. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1458830281-4255-4-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d8465eeab8b3..8b489fcac37b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -321,6 +321,24 @@ static inline void init_hrtick(void)
}
#endif /* CONFIG_SCHED_HRTICK */
+/*
+ * cmpxchg based fetch_or, macro so it works for different integer types
+ */
+#define fetch_or(ptr, mask) \
+ ({ \
+ typeof(ptr) _ptr = (ptr); \
+ typeof(mask) _mask = (mask); \
+ typeof(*_ptr) _old, _val = *_ptr; \
+ \
+ for (;;) { \
+ _old = cmpxchg(_ptr, _val, _val | _mask); \
+ if (_old == _val) \
+ break; \
+ _val = _old; \
+ } \
+ _old; \
+})
+
#if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
/*
* Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,