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Alan Stern
bd5c0ba2cd
Commit:bf28ae5627("tools/memory-model: Remove rb-dep, smp_read_barrier_depends, and lockless_dereference") was merged too early, while it was still in RFC form. This patch adds in the missing pieces. Akira pointed out some typos in the original patch, and he noted that cheatsheet.txt should indicate that READ_ONCE() now implies an address dependency. Andrea suggested documenting the relationship betwwen unsuccessful RMW operations and address dependencies. Andrea pointed out that the macro for rcu_dereference() in linux.def should now use the "once" annotation instead of "deref". He also suggested that the comments should mention commit:5a8897cc76("locking/atomics/alpha: Add smp_read_barrier_depends() to _release()/_relaxed() atomics") ... as an important precursor, and he contributed commit:cb13b424e9("locking/xchg/alpha: Add unconditional memory barrier to cmpxchg()") which is another prerequisite. Suggested-by: Akira Yokosawa <[email protected]> Suggested-by: Andrea Parri <[email protected]> Signed-off-by: Alan Stern <[email protected]> [ Fixed read_read_lock() typo reported by Akira. ] Signed-off-by: Paul E. McKenney <[email protected]> Acked-by: Andrea Parri <[email protected]> Acked-by: Akira Yokosawa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Fixes:bf28ae5627("tools/memory-model: Remove rb-dep, smp_read_barrier_depends, and lockless_dereference") Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
107 lines
4.2 KiB
Modula-2
107 lines
4.2 KiB
Modula-2
// SPDX-License-Identifier: GPL-2.0+
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//
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// An earlier version of this file appears in the companion webpage for
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// "Frightening small children and disconcerting grown-ups: Concurrency
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// in the Linux kernel" by Alglave, Maranget, McKenney, Parri, and Stern,
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// which is to appear in ASPLOS 2018.
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// ONCE
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READ_ONCE(X) __load{once}(X)
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WRITE_ONCE(X,V) { __store{once}(X,V); }
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// Release Acquire and friends
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smp_store_release(X,V) { __store{release}(*X,V); }
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smp_load_acquire(X) __load{acquire}(*X)
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rcu_assign_pointer(X,V) { __store{release}(X,V); }
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rcu_dereference(X) __load{once}(X)
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// Fences
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smp_mb() { __fence{mb} ; }
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smp_rmb() { __fence{rmb} ; }
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smp_wmb() { __fence{wmb} ; }
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smp_mb__before_atomic() { __fence{before-atomic} ; }
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smp_mb__after_atomic() { __fence{after-atomic} ; }
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smp_mb__after_spinlock() { __fence{after-spinlock} ; }
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// Exchange
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xchg(X,V) __xchg{mb}(X,V)
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xchg_relaxed(X,V) __xchg{once}(X,V)
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xchg_release(X,V) __xchg{release}(X,V)
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xchg_acquire(X,V) __xchg{acquire}(X,V)
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cmpxchg(X,V,W) __cmpxchg{mb}(X,V,W)
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cmpxchg_relaxed(X,V,W) __cmpxchg{once}(X,V,W)
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cmpxchg_acquire(X,V,W) __cmpxchg{acquire}(X,V,W)
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cmpxchg_release(X,V,W) __cmpxchg{release}(X,V,W)
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// Spinlocks
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spin_lock(X) { __lock(X) ; }
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spin_unlock(X) { __unlock(X) ; }
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spin_trylock(X) __trylock(X)
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// RCU
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rcu_read_lock() { __fence{rcu-lock}; }
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rcu_read_unlock() { __fence{rcu-unlock};}
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synchronize_rcu() { __fence{sync-rcu}; }
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synchronize_rcu_expedited() { __fence{sync-rcu}; }
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// Atomic
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atomic_read(X) READ_ONCE(*X)
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atomic_set(X,V) { WRITE_ONCE(*X,V) ; }
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atomic_read_acquire(X) smp_load_acquire(X)
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atomic_set_release(X,V) { smp_store_release(X,V); }
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atomic_add(V,X) { __atomic_op(X,+,V) ; }
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atomic_sub(V,X) { __atomic_op(X,-,V) ; }
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atomic_inc(X) { __atomic_op(X,+,1) ; }
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atomic_dec(X) { __atomic_op(X,-,1) ; }
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atomic_add_return(V,X) __atomic_op_return{mb}(X,+,V)
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atomic_add_return_relaxed(V,X) __atomic_op_return{once}(X,+,V)
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atomic_add_return_acquire(V,X) __atomic_op_return{acquire}(X,+,V)
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atomic_add_return_release(V,X) __atomic_op_return{release}(X,+,V)
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atomic_fetch_add(V,X) __atomic_fetch_op{mb}(X,+,V)
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atomic_fetch_add_relaxed(V,X) __atomic_fetch_op{once}(X,+,V)
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atomic_fetch_add_acquire(V,X) __atomic_fetch_op{acquire}(X,+,V)
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atomic_fetch_add_release(V,X) __atomic_fetch_op{release}(X,+,V)
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atomic_inc_return(X) __atomic_op_return{mb}(X,+,1)
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atomic_inc_return_relaxed(X) __atomic_op_return{once}(X,+,1)
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atomic_inc_return_acquire(X) __atomic_op_return{acquire}(X,+,1)
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atomic_inc_return_release(X) __atomic_op_return{release}(X,+,1)
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atomic_fetch_inc(X) __atomic_fetch_op{mb}(X,+,1)
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atomic_fetch_inc_relaxed(X) __atomic_fetch_op{once}(X,+,1)
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atomic_fetch_inc_acquire(X) __atomic_fetch_op{acquire}(X,+,1)
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atomic_fetch_inc_release(X) __atomic_fetch_op{release}(X,+,1)
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atomic_sub_return(V,X) __atomic_op_return{mb}(X,-,V)
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atomic_sub_return_relaxed(V,X) __atomic_op_return{once}(X,-,V)
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atomic_sub_return_acquire(V,X) __atomic_op_return{acquire}(X,-,V)
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atomic_sub_return_release(V,X) __atomic_op_return{release}(X,-,V)
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atomic_fetch_sub(V,X) __atomic_fetch_op{mb}(X,-,V)
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atomic_fetch_sub_relaxed(V,X) __atomic_fetch_op{once}(X,-,V)
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atomic_fetch_sub_acquire(V,X) __atomic_fetch_op{acquire}(X,-,V)
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atomic_fetch_sub_release(V,X) __atomic_fetch_op{release}(X,-,V)
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atomic_dec_return(X) __atomic_op_return{mb}(X,-,1)
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atomic_dec_return_relaxed(X) __atomic_op_return{once}(X,-,1)
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atomic_dec_return_acquire(X) __atomic_op_return{acquire}(X,-,1)
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atomic_dec_return_release(X) __atomic_op_return{release}(X,-,1)
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atomic_fetch_dec(X) __atomic_fetch_op{mb}(X,-,1)
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atomic_fetch_dec_relaxed(X) __atomic_fetch_op{once}(X,-,1)
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atomic_fetch_dec_acquire(X) __atomic_fetch_op{acquire}(X,-,1)
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atomic_fetch_dec_release(X) __atomic_fetch_op{release}(X,-,1)
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atomic_xchg(X,V) __xchg{mb}(X,V)
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atomic_xchg_relaxed(X,V) __xchg{once}(X,V)
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atomic_xchg_release(X,V) __xchg{release}(X,V)
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atomic_xchg_acquire(X,V) __xchg{acquire}(X,V)
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atomic_cmpxchg(X,V,W) __cmpxchg{mb}(X,V,W)
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atomic_cmpxchg_relaxed(X,V,W) __cmpxchg{once}(X,V,W)
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atomic_cmpxchg_acquire(X,V,W) __cmpxchg{acquire}(X,V,W)
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atomic_cmpxchg_release(X,V,W) __cmpxchg{release}(X,V,W)
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atomic_sub_and_test(V,X) __atomic_op_return{mb}(X,-,V) == 0
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atomic_dec_and_test(X) __atomic_op_return{mb}(X,-,1) == 0
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atomic_inc_and_test(X) __atomic_op_return{mb}(X,+,1) == 0
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atomic_add_negative(V,X) __atomic_op_return{mb}(X,+,V) < 0
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