[PATCH v4 4/4] crypto/Documentation: Add crypto_pool kernel API

[Dmitry Safonov]

Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>
---
 Documentation/crypto/crypto_pool.rst | 36 ++++++++++++++++++++++++++++
 Documentation/crypto/index.rst       |  1 +
 2 files changed, 37 insertions(+)
 create mode 100644 Documentation/crypto/crypto_pool.rst

diff --git a/Documentation/crypto/crypto_pool.rst b/Documentation/crypto/crypto_pool.rst
new file mode 100644
index 000000000000..84abd1f2ee80
--- /dev/null
+++ b/Documentation/crypto/crypto_pool.rst
@@ -0,0 +1,36 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Per-CPU pool of crypto requests
+===============================
+
+Overview
+--------
+The crypto pool API manages pre-allocated per-CPU pool of crypto requests,
+providing ability to use crypto requests on fast paths, potentially in atomic
+contexts. The allocation and initialization of the requests should be done
+before their usage as it's slow-path and may sleep.
+
+Order of operations
+-------------------
+You are required to allocate a new pool prior using it and manage its lifetime.
+You can allocate a per-CPU pool of ahash requests by crypto_pool_alloc_ahash().
+It will give you a pool id that you can use further on fast-path for hashing.
+You can increase the reference counter for an allocated pool via
+crypto_pool_get(). Decrease the reference counter by crypto_pool_release().
+When the refcounter hits zero, the pool is scheduled for destruction and you
+can't use the corresponding crypto pool id anymore.
+Note that crypto_pool_get() and crypto_pool_release() must be called
+only for an already existing pool and can be called in atomic contexts.
+
+crypto_pool_start() disables bh and returns you back ``struct crypto_pool *``,
+which is a generic type for different crypto requests and has ``scratch`` area
+that can be used as a temporary buffer for your operation.
+
+crypto_pool_end() enables bh back once you've done with your crypto
+operation.
+
+.. kernel-doc:: include/crypto/pool.h
+   :identifiers:
+
+.. kernel-doc:: crypto/crypto_pool.c
+   :identifiers:
diff --git a/Documentation/crypto/index.rst b/Documentation/crypto/index.rst
index 21338fa92642..3eaf4e964e5b 100644
--- a/Documentation/crypto/index.rst
+++ b/Documentation/crypto/index.rst
@@ -25,6 +25,7 @@ for cryptographic use cases, as well as programming examples.
    devel-algos
    userspace-if
    crypto_engine
+   crypto_pool
    api
    api-samples
    descore-readme
-- 
2.39.0