linux-stable.git/kernel/rcu, branch v4.5

Merge branches 'doc.2015.12.05a', 'exp.2015.12.07a', 'fixes.2015.12.07a', 'list.2015.12.04b' and 'torture.2015.12.05a' into HEAD

2015-12-08T01:02:54+00:00

doc.2015.12.05a:  Documentation updates
exp.2015.12.07a:  Expedited grace-period updates
fixes.2015.12.07a:  Miscellaneous fixes
list.2015.12.04b:  Linked-list updates
torture.2015.12.05a:  Torture-test updates

rcu: Make rcu_gp_init() be bool rather than int

2015-12-08T01:01:33+00:00

The return value from rcu_gp_init() is always used as a bool, so
this commit makes it be a bool.

Reported-by: Iftekhar Ahmed 
Signed-off-by: Paul E. McKenney

rcu: Move wakeup out from under rnp->lock

2015-12-08T01:01:32+00:00

This patch removes a potential deadlock hazard by moving the
wake_up_process() in rcu_spawn_gp_kthread() out from under rnp->lock.

Signed-off-by: Peter Zijlstra 
Signed-off-by: Paul E. McKenney

rcu: Don't redundantly disable irqs in rcu_irq_{enter,exit}()

2015-12-08T01:01:31+00:00

This commit replaces a local_irq_save()/local_irq_restore() pair with
a lockdep assertion that interrupts are already disabled.  This should
remove the corresponding overhead from the interrupt entry/exit fastpaths.

This change was inspired by the fact that Iftekhar Ahmed's mutation
testing showed that removing rcu_irq_enter()'s call to local_ird_restore()
had no effect, which might indicate that interrupts were always enabled
anyway.

Signed-off-by: Paul E. McKenney

rcu: Make cpu_needs_another_gp() be bool

2015-12-08T01:01:31+00:00

The cpu_needs_another_gp() function is currently of type int, but only
returns zero or one.  Bow to reality and make it be of type bool.

Signed-off-by: Paul E. McKenney

rcu: Eliminate unused rcu_init_one() argument

2015-12-08T01:01:19+00:00

Now that the rcu_state structure's ->rda field is compile-time initialized,
there is no need to pass the per-CPU rcu_data structure into rcu_init_one().
This commit therefore eliminates this now-unused parameter.

Signed-off-by: Paul E. McKenney

rcu: Remove TINY_RCU bloat from pointless boot parameters

2015-12-08T00:59:37+00:00

The rcu_expedited, rcu_normal, and rcu_normal_after_boot kernel boot
parameters are pointless in the case of TINY_RCU because in that case
synchronous grace periods, both expedited and normal, are no-ops.
However, these three symbols contribute several hundred bytes of bloat.
This commit therefore uses CPP directives to avoid compiling this code
in TINY_RCU kernels.

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

rcutorture: Print symbolic name for ->gp_state

2015-12-06T01:58:26+00:00

Currently, ->gp_state is printed as an integer, which slows debugging.
This commit therefore prints a symbolic name in addition to the integer.

Signed-off-by: Paul E. McKenney 
[ paulmck: Updated to fix relational operator called out by Dan Carpenter. ]
[ paulmck: More "const", as suggested by Josh Triplett. ]
Reviewed-by: Josh Triplett

rcutorture: Print symbolic name for rcu_torture_writer_state

2015-12-06T01:58:22+00:00

Currently, rcu_torture_writer_state is printed as an integer, which slows
debugging.  This commit therefore prints a symbolic name in addition to
the integer.

Signed-off-by: Paul E. McKenney 
[ paulmck: More "const", as suggested by Josh Triplett. ]
Reviewed-by: Josh Triplett

rcutorture: Dump stack when GP kthread stalls

2015-12-06T01:58:05+00:00

This commit increases debug information in the case where the grace-period
kthread is being prevented from running by dumping that kthread's stack.

Signed-off-by: Paul E. McKenney 
[ paulmck: Split into prior commit and this commit, as suggested by
  Josh Triplett. ]
Reviewed-by: Josh Triplett