[3/3] ipc: add warnings about correct API usage
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Commit Message
When handling synchronous or asynchronous requests, the reply
must be sent explicitly even if the result of the operation is
an error, to avoid the other side timing out. Make note of this
in documentation explicitly.
Cc: stable@dpdk.org
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
doc/guides/prog_guide/multi_proc_support.rst | 7 +++++++
lib/librte_eal/common/include/rte_eal.h | 15 +++++++++++++++
2 files changed, 22 insertions(+)
Comments
03/05/2019 13:50, Anatoly Burakov:
> When handling synchronous or asynchronous requests, the reply
> must be sent explicitly even if the result of the operation is
> an error, to avoid the other side timing out. Make note of this
> in documentation explicitly.
>
> Cc: stable@dpdk.org
>
> Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
> ---
> --- a/lib/librte_eal/common/include/rte_eal.h
> +++ b/lib/librte_eal/common/include/rte_eal.h
> @@ -226,6 +226,11 @@ struct rte_mp_reply {
> * As we create socket channel for primary/secondary communication, use
> * this function typedef to register action for coming messages.
> *
> + * @note When handling IPC request callbacks, the reply must be sent even in
> + * cases of error handling. Simply retuning success or failure will *not* send
retuning -> returning
Will fix on apply.
@@ -309,6 +309,13 @@ If a response is required, a new ``rte_mp_msg`` message descriptor must be
constructed and sent via ``rte_mp_reply()`` function, along with ``peer``
pointer. The resulting response will then be delivered to the correct requestor.
+.. warning::
+ Simply returning a value when processing a request callback will not send a
+ response to the request - it must always be explicitly sent even in case
+ of errors. Implementation of error signalling rests with the application,
+ there is no built-in way to indicate success or error for a request. Failing
+ to do so will cause the requestor to time out while waiting on a response.
+
Misc considerations
~~~~~~~~~~~~~~~~~~~~~~~~
@@ -226,6 +226,11 @@ struct rte_mp_reply {
* As we create socket channel for primary/secondary communication, use
* this function typedef to register action for coming messages.
*
+ * @note When handling IPC request callbacks, the reply must be sent even in
+ * cases of error handling. Simply retuning success or failure will *not* send
+ * a response to the requestor. Implementation of error signalling mechanism
+ * is up to the application.
+ *
* @note No memory allocations should take place inside the callback.
*/
typedef int (*rte_mp_t)(const struct rte_mp_msg *msg, const void *peer);
@@ -237,6 +242,11 @@ typedef int (*rte_mp_t)(const struct rte_mp_msg *msg, const void *peer);
* this function typedef to register action for coming responses to asynchronous
* requests.
*
+ * @note When handling IPC request callbacks, the reply must be sent even in
+ * cases of error handling. Simply retuning success or failure will *not* send
+ * a response to the requestor. Implementation of error signalling mechanism
+ * is up to the application.
+ *
* @note No memory allocations should take place inside the callback.
*/
typedef int (*rte_mp_async_reply_t)(const struct rte_mp_msg *request,
@@ -368,6 +378,11 @@ rte_mp_request_async(struct rte_mp_msg *req, const struct timespec *ts,
* This function will send a reply message in response to a request message
* received previously.
*
+ * @note When handling IPC request callbacks, the reply must be sent even in
+ * cases of error handling. Simply retuning success or failure will *not* send
+ * a response to the requestor. Implementation of error signalling mechanism
+ * is up to the application.
+ *
* @param msg
* The msg argument contains the customized message.
*