diff options
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/memory-model/Documentation/README | 24 | ||||
| -rw-r--r-- | tools/memory-model/Documentation/herd-representation.txt | 110 | ||||
| -rw-r--r-- | tools/memory-model/Documentation/simple.txt | 2 |
3 files changed, 134 insertions, 2 deletions
diff --git a/tools/memory-model/Documentation/README b/tools/memory-model/Documentation/README index 304162743a5b..9999c1effdb6 100644 --- a/tools/memory-model/Documentation/README +++ b/tools/memory-model/Documentation/README @@ -9,6 +9,8 @@ depending on what you know and what you would like to learn. Please note that the documents later in this list assume that the reader understands the material provided by documents earlier in this list. +If LKMM-specific terms lost you, glossary.txt might help you. + o You are new to Linux-kernel concurrency: simple.txt o You have some background in Linux-kernel concurrency, and would @@ -21,6 +23,9 @@ o You are familiar with the Linux-kernel concurrency primitives that you need, and just want to get started with LKMM litmus tests: litmus-tests.txt +o You would like to access lock-protected shared variables without + having their corresponding locks held: locking.txt + o You are familiar with Linux-kernel concurrency, and would like a detailed intuitive understanding of LKMM, including situations involving more than two threads: recipes.txt @@ -28,12 +33,18 @@ o You are familiar with Linux-kernel concurrency, and would o You would like a detailed understanding of what your compiler can and cannot do to control dependencies: control-dependencies.txt +o You would like to mark concurrent normal accesses to shared + variables so that intentional "racy" accesses can be properly + documented, especially when you are responding to complaints + from KCSAN: access-marking.txt + o You are familiar with Linux-kernel concurrency and the use of LKMM, and would like a quick reference: cheatsheet.txt 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 @@ -61,10 +72,21 @@ control-dependencies.txt explanation.txt Detailed description of the memory model. +glossary.txt + Brief definitions of LKMM-related terms. + +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. +locking.txt + Rules for accessing lock-protected shared variables outside of + their corresponding critical sections. + ordering.txt Overview of the Linux kernel's low-level memory-ordering primitives by category. diff --git a/tools/memory-model/Documentation/herd-representation.txt b/tools/memory-model/Documentation/herd-representation.txt new file mode 100644 index 000000000000..ed988906f2b7 --- /dev/null +++ b/tools/memory-model/Documentation/herd-representation.txt @@ -0,0 +1,110 @@ +# +# 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 | + ------------------------------------------------------------------------------ diff --git a/tools/memory-model/Documentation/simple.txt b/tools/memory-model/Documentation/simple.txt index 4c789ec8334f..21f06c1d1b70 100644 --- a/tools/memory-model/Documentation/simple.txt +++ b/tools/memory-model/Documentation/simple.txt @@ -266,5 +266,5 @@ More complex use cases ====================== If the alternatives above do not do what you need, please look at the -recipes-pairs.txt file to peel off the next layer of the memory-ordering +recipes.txt file to peel off the next layer of the memory-ordering onion. |