Commit-ID: 5529578a27288d11d4d15635c258c6dde0f0fb10
Gitweb: http://git.kernel.org/tip/5529578a27288d11d4d15635c258c6dde0f0fb10
Author: Frederic Weisbecker <fweisbec@xxxxxxxxx>
AuthorDate: Thu, 24 Mar 2016 15:38:01 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 29 Mar 2016 11:52:11 +0200
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@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1458830281-4255-4-git-send-email-fweisbec@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/atomic.h | 21 ---------------------
kernel/sched/core.c | 18 ++++++++++++++++++
2 files changed, 18 insertions(+), 21 deletions(-)
diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index 3d64c08..506c353 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -579,27 +579,6 @@ static inline int atomic_fetch_or(atomic_t *p, int mask)
}
#endif
-/**
- * fetch_or - perform *ptr |= mask and return old value of *ptr
- * @ptr: pointer to value
- * @mask: mask to OR on the value
- *
- * cmpxchg based fetch_or, macro so it works for different integer types
- */
-#ifndef fetch_or
-#define fetch_or(ptr, mask) \
-({ typeof(*(ptr)) __old, __val = *(ptr); \
- for (;;) { \
- __old = cmpxchg((ptr), __val, __val | (mask)); \
- if (__old == __val) \
- break; \
- __val = __old; \
- } \
- __old; \
-})
-#endif
-
-
#ifdef CONFIG_GENERIC_ATOMIC64
#include <asm-generic/atomic64.h>
#endif
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d8465ee..8b489fc 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,
--
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