From: Ben Pfaff Date: Fri, 31 Dec 2004 07:06:14 +0000 (+0000) Subject: Clarification. X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b69e562128765fab509c42ec097961097d04d4a3;p=pintos-anon Clarification. --- diff --git a/doc/tour.texi b/doc/tour.texi index ed1f92b..845a1c8 100644 --- a/doc/tour.texi +++ b/doc/tour.texi @@ -553,8 +553,10 @@ A semaphore initialized to 0 can be useful for waiting for an event that will happen exactly once. For example, suppose thread @var{A} starts another thread @var{B} and wants to wait for @var{B} to signal that some activity is complete. @var{A} can create a semaphore -initialized to 0, pass it to @var{B}, and then ``down'' the semaphore. -When @var{B} finishes its activity, it ``ups'' the semaphore. +initialized to 0, pass it to @var{B} as it starts it, and then +``down'' the semaphore. When @var{B} finishes its activity, it +``ups'' the semaphore. This works regardless of whether @var{A} +``downs'' the semaphore or @var{B} ``ups'' it first. Pintos declared its semaphore type and operations on them in @file{threads/synch.h}.