fbfaf85190
If an input number x for int_sqrt64() has the highest bit set, then
fls64(x) is 64. (1UL << 64) is an overflow and breaks the algorithm.
Subtracting 1 is a better guess for the initial value of m anyway and
that's what also done in int_sqrt() implicitly [*].
[*] Note how int_sqrt() uses __fls() with two underscores, which already
returns the proper raw bit number.
In contrast, int_sqrt64() used fls64(), and that returns bit numbers
illogically starting at 1, because of error handling for the "no
bits set" case. Will points out that he bug probably is due to a
copy-and-paste error from the regular int_sqrt() case.
Signed-off-by: Florian La Roche <Florian.LaRoche@googlemail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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.