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In current implementation, tls records are encrypted & transmitted serially. Till the time the previously submitted user data is encrypted, the implementation waits and on finish starts transmitting the record. This approach of encrypt-one record at a time is inefficient when asynchronous crypto accelerators are used. For each record, there are overheads of interrupts, driver softIRQ scheduling etc. Also the crypto accelerator sits idle most of time while an encrypted record's pages are handed over to tcp stack for transmission. This patch enables encryption of multiple records in parallel when an async capable crypto accelerator is present in system. This is achieved by allowing the user space application to send more data using sendmsg() even while previously issued data is being processed by crypto accelerator. This requires returning the control back to user space application after submitting encryption request to accelerator. This also means that zero-copy mode of encryption cannot be used with async accelerator as we must be done with user space application buffer before returning from sendmsg(). There can be multiple records in flight to/from the accelerator. Each of the record is represented by 'struct tls_rec'. This is used to store the memory pages for the record. After the records are encrypted, they are added in a linked list called tx_ready_list which contains encrypted tls records sorted as per tls sequence number. The records from tx_ready_list are transmitted using a newly introduced function called tls_tx_records(). The tx_ready_list is polled for any record ready to be transmitted in sendmsg(), sendpage() after initiating encryption of new tls records. This achieves parallel encryption and transmission of records when async accelerator is present. There could be situation when crypto accelerator completes encryption later than polling of tx_ready_list by sendmsg()/sendpage(). Therefore we need a deferred work context to be able to transmit records from tx_ready_list. The deferred work context gets scheduled if applications are not sending much data through the socket. If the applications issue sendmsg()/sendpage() in quick succession, then the scheduling of tx_work_handler gets cancelled as the tx_ready_list would be polled from application's context itself. This saves scheduling overhead of deferred work. The patch also brings some side benefit. We are able to get rid of the concept of CLOSED record. This is because the records once closed are either encrypted and then placed into tx_ready_list or if encryption fails, the socket error is set. This simplifies the kernel tls sendpath. However since tls_device.c is still using macros, accessory functions for CLOSED records have been retained. Signed-off-by: Vakul Garg <vakul.garg@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.