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Davidlohr Bueso
3a6bfbc91d
The arch_mutex_cpu_relax() function, introduced by 34b133f, is
hacky and ugly. It was added a few years ago to address the fact
that common cpu_relax() calls include yielding on s390, and thus
impact the optimistic spinning functionality of mutexes. Nowadays
we use this function well beyond mutexes: rwsem, qrwlock, mcs and
lockref. Since the macro that defines the call is in the mutex header,
any users must include mutex.h and the naming is misleading as well.
This patch (i) renames the call to cpu_relax_lowlatency ("relax, but
only if you can do it with very low latency") and (ii) defines it in
each arch's asm/processor.h local header, just like for regular cpu_relax
functions. On all archs, except s390, cpu_relax_lowlatency is simply cpu_relax,
and thus we can take it out of mutex.h. While this can seem redundant,
I believe it is a good choice as it allows us to move out arch specific
logic from generic locking primitives and enables future(?) archs to
transparently define it, similarly to System Z.
Signed-off-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Aurelien Jacquiot <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Bharat Bhushan <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Chen Liqin <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Chris Zankel <[email protected]>
Cc: David Howells <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Deepthi Dharwar <[email protected]>
Cc: Dominik Dingel <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Guan Xuetao <[email protected]>
Cc: Haavard Skinnemoen <[email protected]>
Cc: Hans-Christian Egtvedt <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Hirokazu Takata <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Cc: James E.J. Bottomley <[email protected]>
Cc: James Hogan <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Jesper Nilsson <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Jonas Bonn <[email protected]>
Cc: Joseph Myers <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Koichi Yasutake <[email protected]>
Cc: Lennox Wu <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mark Salter <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: Max Filippov <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Mikael Starvik <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Paul Burton <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Qais Yousef <[email protected]>
Cc: Qiaowei Ren <[email protected]>
Cc: Rafael Wysocki <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Richard Kuo <[email protected]>
Cc: Russell King <[email protected]>
Cc: Steven Miao <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Stratos Karafotis <[email protected]>
Cc: Tim Chen <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Vasily Kulikov <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Waiman Long <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Wolfram Sang <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
89 lines
2.1 KiB
C
89 lines
2.1 KiB
C
/*
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* include/asm-alpha/processor.h
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*
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* Copyright (C) 1994 Linus Torvalds
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*/
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#ifndef __ASM_ALPHA_PROCESSOR_H
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#define __ASM_ALPHA_PROCESSOR_H
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#include <linux/personality.h> /* for ADDR_LIMIT_32BIT */
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/*
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* Returns current instruction pointer ("program counter").
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*/
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#define current_text_addr() \
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({ void *__pc; __asm__ ("br %0,.+4" : "=r"(__pc)); __pc; })
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/*
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* We have a 42-bit user address space: 4TB user VM...
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*/
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#define TASK_SIZE (0x40000000000UL)
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#define STACK_TOP \
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(current->personality & ADDR_LIMIT_32BIT ? 0x80000000 : 0x00120000000UL)
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#define STACK_TOP_MAX 0x00120000000UL
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/* This decides where the kernel will search for a free chunk of vm
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* space during mmap's.
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*/
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#define TASK_UNMAPPED_BASE \
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((current->personality & ADDR_LIMIT_32BIT) ? 0x40000000 : TASK_SIZE / 2)
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typedef struct {
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unsigned long seg;
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} mm_segment_t;
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/* This is dead. Everything has been moved to thread_info. */
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struct thread_struct { };
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#define INIT_THREAD { }
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/* Return saved PC of a blocked thread. */
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struct task_struct;
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extern unsigned long thread_saved_pc(struct task_struct *);
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/* Do necessary setup to start up a newly executed thread. */
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extern void start_thread(struct pt_regs *, unsigned long, unsigned long);
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/* Free all resources held by a thread. */
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extern void release_thread(struct task_struct *);
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unsigned long get_wchan(struct task_struct *p);
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#define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
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#define KSTK_ESP(tsk) \
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((tsk) == current ? rdusp() : task_thread_info(tsk)->pcb.usp)
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#define cpu_relax() barrier()
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#define cpu_relax_lowlatency() cpu_relax()
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#define ARCH_HAS_PREFETCH
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#define ARCH_HAS_PREFETCHW
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#define ARCH_HAS_SPINLOCK_PREFETCH
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#ifndef CONFIG_SMP
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/* Nothing to prefetch. */
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#define spin_lock_prefetch(lock) do { } while (0)
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#endif
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extern inline void prefetch(const void *ptr)
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{
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__builtin_prefetch(ptr, 0, 3);
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}
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extern inline void prefetchw(const void *ptr)
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{
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__builtin_prefetch(ptr, 1, 3);
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}
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#ifdef CONFIG_SMP
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extern inline void spin_lock_prefetch(const void *ptr)
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{
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__builtin_prefetch(ptr, 1, 3);
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}
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#endif
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#endif /* __ASM_ALPHA_PROCESSOR_H */
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