bf28ae5627
Since commit76ebbe78f7("locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE()") was merged for the 4.15 kernel, it has not been necessary to use smp_read_barrier_depends(). Similarly, commit59ecbbe7b3("locking/barriers: Kill lockless_dereference()") removed lockless_dereference() from the kernel. Since these primitives are no longer part of the kernel, they do not belong in the Linux Kernel Memory Consistency Model. This patch removes them, along with the internal rb-dep relation, and updates the revelant documentation. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akiyks@gmail.com Cc: boqun.feng@gmail.com Cc: dhowells@redhat.com Cc: j.alglave@ucl.ac.uk Cc: linux-arch@vger.kernel.org Cc: luc.maranget@inria.fr Cc: nborisov@suse.com Cc: npiggin@gmail.com Cc: parri.andrea@gmail.com Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1519169112-20593-12-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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{deref}(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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