diff options
Diffstat (limited to 'tools/memory-model/Documentation/access-marking.txt')
| -rw-r--r-- | tools/memory-model/Documentation/access-marking.txt | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/tools/memory-model/Documentation/access-marking.txt b/tools/memory-model/Documentation/access-marking.txt index f531b0837356..3fbe77fd564a 100644 --- a/tools/memory-model/Documentation/access-marking.txt +++ b/tools/memory-model/Documentation/access-marking.txt @@ -25,6 +25,11 @@ The Linux kernel provides the following access-marking options: 4. WRITE_ONCE(), for example, "WRITE_ONCE(a, b);" The various forms of atomic_set() also fit in here. +5. __data_racy, for example "int __data_racy a;" + +6. KCSAN's negative-marking assertions, ASSERT_EXCLUSIVE_ACCESS() + and ASSERT_EXCLUSIVE_WRITER(), are described in the + "ACCESS-DOCUMENTATION OPTIONS" section below. These may be used in combination, as shown in this admittedly improbable example: @@ -206,6 +211,23 @@ because doing otherwise prevents KCSAN from detecting violations of your code's synchronization rules. +Use of __data_racy +------------------ + +Adding the __data_racy type qualifier to the declaration of a variable +causes KCSAN to treat all accesses to that variable as if they were +enclosed by data_race(). However, __data_racy does not affect the +compiler, though one could imagine hardened kernel builds treating the +__data_racy type qualifier as if it was the volatile keyword. + +Note well that __data_racy is subject to the same pointer-declaration +rules as are other type qualifiers such as const and volatile. +For example: + + int __data_racy *p; // Pointer to data-racy data. + int *__data_racy p; // Data-racy pointer to non-data-racy data. + + ACCESS-DOCUMENTATION OPTIONS ============================ @@ -343,7 +365,7 @@ as follows: Because foo is read locklessly, all accesses are marked. The purpose of the ASSERT_EXCLUSIVE_WRITER() is to allow KCSAN to check for a buggy -concurrent lockless write. +concurrent write, whether marked or not. Lock-Protected Writes With Heuristic Lockless Reads |