25de4a0b7b
Alex Elder says: ==================== net: ipa: use IDs to track transaction state This series is the first of three groups of changes that simplify the way the IPA driver tracks the state of its transactions. Each GSI channel has a fixed number of transactions allocated at initialization time. The number allocated matches the number of TREs in the transfer ring associated with the channel. This is because the transfer ring limits the number of transfers that can ever be underway, and in the worst case, each transaction represents a single TRE. Transactions go through various states during their lifetime. Currently a set of lists keeps track of which transactions are in each state. Initially, all transactions are free. An allocated transaction is placed on the allocated list. Once an allocated transaction is committed, it is moved from the allocated to the committed list. When a committed transaction is sent to hardware (via a doorbell) it is moved to the pending list. When hardware signals that some work has completed, transactions are moved to the completed list. Finally, when a completed transaction is polled it's moved to the polled list before being removed when it becomes free. Changing a transaction's state thus normally involves manipulating two lists, and to prevent corruption a spinlock is held while the lists are updated. Transactions move through their states in a well-defined sequence though, and they do so strictly in order. So transaction 0 is always allocated before transaction 1; transaction 0 is always committed before transaction 1; and so on, through completion, polling, and becoming free. Because of this, it's sufficient to just keep track of which transaction is the first in each state. The rest of the transactions in a given state can be derived from the first transaction in an "adjacent" state. As a result, we can track the state of all transactions with a set of indexes, and can update these without the need for a spinlock. This first group of patches just defines the set of indexes that will be used for this new way of tracking transaction state. Two more groups of patches will follow. I've broken the 17 patches into these three groups to facilitate review. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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.
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.