On Fri, Apr 21, 2017 at 10:12:53PM +0800, Alex Shi wrote: > diff --git a/Documentation/locking/rt-mutex-design.txt > b/Documentation/locking/rt-mutex-design.txt > index 8666070..11beb55 100644 > --- a/Documentation/locking/rt-mutex-design.txt > +++ b/Documentation/locking/rt-mutex-design.txt > @@ -97,9 +97,9 @@ waiter - A waiter is a struct that is stored on the stack > of a blocked > a process being blocked on the mutex, it is fine to allocate > the waiter on the process's stack (local variable). This > structure holds a pointer to the task, as well as the mutex that > - the task is blocked on. It also has the plist node structures to > - place the task in the waiter_list of a mutex as well as the > - pi_list of a mutex owner task (described below). > + the task is blocked on. It also has a rbtree node structures to > + place the task in waiters rbtree of a mutex as well as the > + pi_waiters rbtree of a mutex owner task (described below).
whitespace fail > > waiter is sometimes used in reference to the task that is waiting > on a mutex. This is the same as waiter->task. > @@ -179,53 +179,35 @@ again. > | > F->L5-+ > > +If the G process has highest priority in the chain, then all the tasks up > +the chain (A and B in this example), must have their priorities increased > +to that of G. No, only the top task that's actually runnable needs to be modified. The rest we don't care about because they're blocked. > +Since the pi_waiters of a task holds an order by priority of all the top > waiters > +of all the mutexes that the task owns, rt_mutex_getprio simply needs to > compare > +the top pi waiter to its own normal priority, and return the higher priority > +back. rt_mutex_getprio() doesn't exist. > +The main operation of this function is summarized by Thomas Gleixner in > +rtmutex.c. See the 'Chain walk basics and protection scope' comment for > further > +details. Since all the useful bits are there anyway, why keep this document around at all?
