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Commit e8adbac0 authored by Andrea Parri's avatar Andrea Parri Committed by Paul E. McKenney
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tools/memory-model: Document herd7 (abstract) representation 

The Linux-kernel memory model (LKMM) source code and the herd7 tool are
closely linked in that the latter is responsible for (pre)processing
each C-like macro of a litmus test, and for providing the LKMM with a
set of events, or "representation", corresponding to the given macro.
This commit therefore provides herd-representation.txt to document
the representations of the concurrency macros, following their
"classification" in Documentation/atomic_t.txt.

Link: https://lore.kernel.org/all/ZnFZPJlILp5B9scN@andrea/Suggested-by: default avatarHernan Ponce de Leon <hernan.poncedeleon@huaweicloud.com>
Signed-off-by: default avatarAndrea Parri <parri.andrea@gmail.com>
Reviewed-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Reviewed-by: default avatarHernan Ponce de Leon <hernan.poncedeleon@huaweicloud.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 8400291e
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tools/memory-model/Documentation/README
View file @ e8adbac0
......@@ -33,7 +33,8 @@ o You are familiar with Linux-kernel concurrency and the use of
o You are familiar with Linux-kernel concurrency and the use
of LKMM, and would like to learn about LKMM's requirements,
rationale, and implementation: explanation.txt
rationale, and implementation: explanation.txt and
herd-representation.txt
o You are interested in the publications related to LKMM, including
hardware manuals, academic literature, standards-committee
......@@ -61,6 +62,10 @@ control-dependencies.txt
explanation.txt
Detailed description of the memory model.
herd-representation.txt
The (abstract) representation of the Linux-kernel concurrency
primitives in terms of events.
litmus-tests.txt
The format, features, capabilities, and limitations of the litmus
tests that LKMM can evaluate.
......
tools/memory-model/Documentation/herd-representation.txt 0 → 100644
View file @ e8adbac0
#
# Legend:
# R, a Load event
# W, a Store event
# F, a Fence event
# LKR, a Lock-Read event
# LKW, a Lock-Write event
# UL, an Unlock event
# LF, a Lock-Fail event
# RL, a Read-Locked event
# RU, a Read-Unlocked event
# R*, a Load event included in RMW
# W*, a Store event included in RMW
# SRCU, a Sleepable-Read-Copy-Update event
#
# po, a Program-Order link
# rmw, a Read-Modify-Write link - every rmw link is a po link
#
# By convention, a blank line in a cell means "same as the preceding line".
#
# Disclaimer. The table includes representations of "add" and "and" operations;
# corresponding/identical representations of "sub", "inc", "dec" and "or", "xor",
# "andnot" operations are omitted.
#
------------------------------------------------------------------------------
| C macro | Events |
------------------------------------------------------------------------------
| Non-RMW ops | |
------------------------------------------------------------------------------
| READ_ONCE | R[once] |
| atomic_read | |
| WRITE_ONCE | W[once] |
| atomic_set | |
| smp_load_acquire | R[acquire] |
| atomic_read_acquire | |
| smp_store_release | W[release] |
| atomic_set_release | |
| smp_store_mb | W[once] ->po F[mb] |
| smp_mb | F[mb] |
| smp_rmb | F[rmb] |
| smp_wmb | F[wmb] |
| smp_mb__before_atomic | F[before-atomic] |
| smp_mb__after_atomic | F[after-atomic] |
| spin_unlock | UL |
| spin_is_locked | On success: RL |
| | On failure: RU |
| smp_mb__after_spinlock | F[after-spinlock] |
| smp_mb__after_unlock_lock | F[after-unlock-lock] |
| rcu_read_lock | F[rcu-lock] |
| rcu_read_unlock | F[rcu-unlock] |
| synchronize_rcu | F[sync-rcu] |
| rcu_dereference | R[once] |
| rcu_assign_pointer | W[release] |
| srcu_read_lock | R[srcu-lock] |
| srcu_down_read | |
| srcu_read_unlock | W[srcu-unlock] |
| srcu_up_read | |
| synchronize_srcu | SRCU[sync-srcu] |
| smp_mb__after_srcu_read_unlock | F[after-srcu-read-unlock] |
------------------------------------------------------------------------------
| RMW ops w/o return value | |
------------------------------------------------------------------------------
| atomic_add | R*[noreturn] ->rmw W*[once] |
| atomic_and | |
| spin_lock | LKR ->po LKW |
------------------------------------------------------------------------------
| RMW ops w/ return value | |
------------------------------------------------------------------------------
| atomic_add_return | F[mb] ->po R*[once] |
| | ->rmw W*[once] ->po F[mb] |
| atomic_fetch_add | |
| atomic_fetch_and | |
| atomic_xchg | |
| xchg | |
| atomic_add_negative | |
| atomic_add_return_relaxed | R*[once] ->rmw W*[once] |
| atomic_fetch_add_relaxed | |
| atomic_fetch_and_relaxed | |
| atomic_xchg_relaxed | |
| xchg_relaxed | |
| atomic_add_negative_relaxed | |
| atomic_add_return_acquire | R*[acquire] ->rmw W*[once] |
| atomic_fetch_add_acquire | |
| atomic_fetch_and_acquire | |
| atomic_xchg_acquire | |
| xchg_acquire | |
| atomic_add_negative_acquire | |
| atomic_add_return_release | R*[once] ->rmw W*[release] |
| atomic_fetch_add_release | |
| atomic_fetch_and_release | |
| atomic_xchg_release | |
| xchg_release | |
| atomic_add_negative_release | |
------------------------------------------------------------------------------
| Conditional RMW ops | |
------------------------------------------------------------------------------
| atomic_cmpxchg | On success: F[mb] ->po R*[once] |
| | ->rmw W*[once] ->po F[mb] |
| | On failure: R*[once] |
| cmpxchg | |
| atomic_add_unless | |
| atomic_cmpxchg_relaxed | On success: R*[once] ->rmw W*[once] |
| | On failure: R*[once] |
| atomic_cmpxchg_acquire | On success: R*[acquire] ->rmw W*[once] |
| | On failure: R*[once] |
| atomic_cmpxchg_release | On success: R*[once] ->rmw W*[release] |
| | On failure: R*[once] |
| spin_trylock | On success: LKR ->po LKW |
| | On failure: LF |
------------------------------------------------------------------------------
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