mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-03-13 09:18:38 +01:00
622838f3fd
Making iterator macros keep track of the amount of data copied is pretty
easy and it has several benefits:
1) we no longer need the mess like (from += v.iov_len) - v.iov_len
in the callbacks - initial value + total amount copied so far would do
just fine.
2) less obviously, we no longer need to remember the initial amount
of data we wanted to copy; the loops in iterator macros are along the lines
of
wanted = bytes;
while (bytes) {
copy some
bytes -= copied
if short copy
break
}
bytes = wanted - bytes;
Replacement is
offs = 0;
while (bytes) {
copy some
offs += copied
bytes -= copied
if short copy
break
}
bytes = offs;
That wouldn't be a win per se, but unlike the initial value of bytes, the amount
copied so far *is* useful in callbacks.
3) in some cases (csum_and_copy_..._iter()) we already had offs manually
maintained by the callbacks. With that change we can drop that.
Less boilerplate and more readable code...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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.