linux-stable.git/kernel/rcutiny.c, branch master

rcu: Move RCU-related source code to kernel/rcu directory

2013-10-15T19:53:31+00:00

Signed-off-by: Paul E. McKenney 
Reviewed-by: Ingo Molnar

Merge branch 'idle.2013.09.25a' into HEAD

2013-10-15T19:49:59+00:00

idle.2013.09.25a: Topic branch for idle entry-/exit-related changes.

Merge branch 'gp.2013.09.25a' into HEAD

2013-10-15T19:47:04+00:00

gp.2013.09.25a: Topic branch for grace-period updates.

rcu: Consistent rcu_is_watching() naming

2013-09-25T13:45:06+00:00

The old rcu_is_cpu_idle() function is just __rcu_is_watching() with
preemption disabled.  This commit therefore renames rcu_is_cpu_idle()
to rcu_is_watching.

Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

rcu: Is it safe to enter an RCU read-side critical section?

2013-09-25T13:44:41+00:00

There is currently no way for kernel code to determine whether it
is safe to enter an RCU read-side critical section, in other words,
whether or not RCU is paying attention to the currently running CPU.
Given the large and increasing quantity of code shared by the idle loop
and non-idle code, the this shortcoming is becoming increasingly painful.

This commit therefore adds __rcu_is_watching(), which returns true if
it is safe to enter an RCU read-side critical section on the currently
running CPU.  This function is quite fast, using only a __this_cpu_read().
However, the caller must disable preemption.

Reported-by: Steven Rostedt 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

rcu: Avoid sparse warnings in rcu_nocb_wake trace event

2013-09-23T16:18:17+00:00

The event-tracing macros do not like bool tracing arguments, so this
commit makes them be of type char.  This change has the knock-on effect
of making it illegal to pass a pointer into one of these arguments, so
also change rcutiny's first call to trace_rcu_batch_end() to convert
from pointer to boolean, prefixing with "!!".

Reported-by: kbuild test robot 
Signed-off-by: Paul E. McKenney

rcu: Have rcutiny tracepoints use tracepoint_string()

2013-09-23T16:15:31+00:00

This commit extends the work done in f7f7bac9 (rcu: Have the RCU
tracepoints use the tracepoint_string infrastructure) to cover rcutiny.

Signed-off-by: Paul E. McKenney 
Cc: Steven Rostedt

rcu: Add const annotation to char * for RCU tracepoints and functions

2013-07-29T21:07:49+00:00

All the RCU tracepoints and functions that reference char pointers do
so with just 'char *' even though they do not modify the contents of
the string itself. This will cause warnings if a const char * is used
in one of these functions.

The RCU tracepoints store the pointer to the string to refer back to them
when the trace output is displayed. As this can be minutes, hours or
even days later, those strings had better be constant.

This change also opens the door to allow the RCU tracepoint strings and
their addresses to be exported so that userspace tracing tools can
translate the contents of the pointers of the RCU tracepoints.

Signed-off-by: Steven Rostedt

rcu: Shrink TINY_RCU by reworking CPU-stall ifdefs

2013-06-10T20:45:53+00:00

TINY_RCU's reset_cpu_stall_ticks() and check_cpu_stalls() functions
are defined unconditionally, and are empty functions if CONFIG_RCU_TRACE
is disabled (which in turns disables detection of RCU CPU stalls).
This commit saves a few lines of source code by defining these functions
only if CONFIG_RCU_TRACE=y.

Signed-off-by: Paul E. McKenney

rcu: Simplify RCU_TINY RCU callback invocation

2013-06-10T20:45:51+00:00

TINY_PREEMPT_RCU could use a kthread to handle RCU callback invocation,
which required an API to abstract kthread vs. softirq invocation.
Now that TINY_PREEMPT_RCU is no longer with us, this commit retires
this API in favor of direct use of the relevant softirq primitives.

Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett