tree 4b3953b84fffb65bdf7b54955aed40d45d538e4a
parent 18bcd0c8cb7d85a9063b88ec810dc1cdc0974518
author Steven Rostedt <srostedt@redhat.com> 1301084466 -0400
committer Steven Rostedt <rostedt@goodmis.org> 1301321442 -0400

WARN_ON_SMP(): Add comment to explain ({0;})

The define to use ({0;}) for the !CONFIG_SMP case of WARN_ON_SMP()
can be confusing. As the WARN_ON_SMP() needs to be a nop when
CONFIG_SMP is not set, including all its parameters must not be
evaluated, and that it must work as both a stand alone statement
and inside an if condition, we define it to a funky ({0;}).

A simple "0" will not work as it causes gcc to give the warning that
the statement has no effect.

As this strange definition has raised a few eyebrows from some
major kernel developers, it is wise to document why we create such
a work of art.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>