Subject: Re: [PATCH v7 2/2] eal: add generic thread-local-storage functions

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On Tue,  5 Jan 2021 19:06:35 +0200, Tal Shnaiderman wrote:

quoted

Add support for TLS functionality in EAL.

The following functions are added:
rte_thread_tls_key_create - function to create a TLS data key.
rte_thread_tls_key_delete - function to delete a TLS data key.
rte_thread_tls_value_set - function to set value bound to the TLS key
rte_thread_tls_value_get - function to get value bound to the TLS key

"Function to" is redundant both here and in Doxygen comments.

quoted

TLS key will be defined by the new type rte_tls_key.

Please use present tense when describing patch content.

quoted

The API Allocates the thread local storage (TLS) key.

Typo: "allocates".

quoted

Any thread of the process can subsequently use this key to store and
retrieve values that are local to the thread.

Those functions are added in addition to TLS capability in
rte_per_lcore.h to allow user to use the thread reasouce destruction
capability in rte_thread_tls_key_create.

Err, I assumed we're abstracting pthread, otherwise the capability has
already been there. Also, a typo: "resource".

quoted

Windows implementation is under librte_eal/windows and implemented
using WIN32 API for Windows only.

common implementation is under librte_eal/common and implemented

using

quoted

pthread for UNIX compilation.

librte_eal/unix

[...]

quoted

+/**
+ * Opaque pointer for TLS key.
+ */
+typedef struct eal_tls_key *rte_tls_key;

Suggesting "TLS key type, an opaque pointer". Now it's unclear if there's a
TLS key and a pointer to it or TLS key is an opaque pointer itself (which is the
case, API-wise).

quoted

+
 /**
  * Set core affinity of the current thread.
  * Support both EAL and non-EAL thread and update TLS.

@@ -36,4 +41,67 @@ int rte_thread_set_affinity(rte_cpuset_t *cpusetp);
  */
 void rte_thread_get_affinity(rte_cpuset_t *cpusetp);

+/**
+ * Function to create a TLS data key visible to all threads in the
+process
+ * function need to be called once to create a key usable by all threads.

The sentences repeat each other and are not separated.

quoted

+ * rte_tls_key is an opaque pointer used to store the allocated key.
+ * which is later used to get/set a value.
+ * and optional destructor can be set to be called when a thread expires.

"expires" -> "exits", here and below.

No need to repeat parameter description in function description.

quoted

+ *
+ * @param key
+ *   Pointer to store the allocated rte_tls_key
+ * @param destructor
+ *   The function to be called when the thread expires.
+ *   Ignored on Windows OS.
+ *
+ * @return
+ *   On success, zero.
+ *   On failure, a negative number.
+ */
+
+__rte_experimental
+int rte_thread_tls_key_create(rte_tls_key *key, void
+(*destructor)(void *));

quoted

+
+/**
+ * Function to delete a TLS data key visible to all threads in the
+process
+ * rte_tls_key is the opaque pointer allocated by

rte_thread_tls_key_create.

quoted

+ *
+ * @param key
+ *   The rte_tls_key will contain the allocated key

"Will"? It's an rte_tls_key key allocated by rte_thread_tls_key_create().

quoted

+ *
+ * @return
+ *   On success, zero.
+ *   On failure, a negative number.
+ */
+__rte_experimental
+int rte_thread_tls_key_delete(rte_tls_key key);

quoted

+/**
+ * Function to set value bound to the tls key on behalf of the
+calling thread

"tls" -> "TLS"

quoted

+ *
+ * @param key
+ *   The rte_tls_key key allocated by rte_thread_tls_key_create.
+ * @param value
+ *   The value bound to the rte_tls_key key for the calling thread.
+ *
+ * @return
+ *   On success, zero.
+ *   On failure, a negative number.
+ */
+__rte_experimental
+int rte_thread_tls_value_set(rte_tls_key key, const void *value);
+
+/**
+ * Function to get value bound to the tls key on behalf of the
+calling thread

"tls" -> "TLS"

quoted

+ *
+ * @param key
+ *   The rte_tls_key key allocated by rte_thread_tls_key_create.
+ *
+ * @return
+ *   On success, value data pointer (can also be NULL).
+ *   On failure, NULL and an error number is set in rte_errno.
+ */
+__rte_experimental
+void *rte_thread_tls_value_get(rte_tls_key key);
+
 #endif /* _RTE_THREAD_H_ */

quoted

diff --git a/lib/librte_eal/windows/rte_thread.c

b/lib/librte_eal/windows/rte_thread.c
new file mode 100644
index 0000000000..4ced283c62

--- /dev/null
+++ b/lib/librte_eal/windows/rte_thread.c

@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright 2021 Mellanox Technologies, Ltd  */
+
+#include <rte_common.h>
+#include <rte_errno.h>
+#include <rte_thread.h>
+#include <rte_windows.h>
+
+struct eal_tls_key {
+     DWORD thread_index;
+};
+
+int
+rte_thread_tls_key_create(rte_tls_key *key,
+             __rte_unused void (*destructor)(void *)) {
+     *key = malloc(sizeof(struct eal_tls_key));

sizeof(*key)

quoted

+     if ((*key) == NULL) {
+             RTE_LOG(DEBUG, EAL, "Cannot allocate tls key.");

"tls" -> "TLS"

quoted

+             return -1;
+     }
+     (*key)->thread_index = TlsAlloc();
+     if ((*key)->thread_index == TLS_OUT_OF_INDEXES) {
+             RTE_LOG_WIN32_ERR("TlsAlloc()");
+             free(*key);
+             return -1;
+     }
+     return 0;
+}
+
+int
+rte_thread_tls_key_delete(rte_tls_key key) {
+     if (!key) {
+             RTE_LOG(DEBUG, EAL, "invalid tls key passed to
+function.\n");

"tls" -> "TLS"
Messages should start with a capital letter.
To which "function"?

quoted

+             return -1;
+     }
+     if (!TlsFree(key->thread_index)) {
+             RTE_LOG_WIN32_ERR("TlsFree()");
+             free(key);
+             return -1;
+     }
+     free(key);
+     return 0;
+}

Thanks for the review Dmitry, I'll fix and resend both patches.