linux/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

2015-12-08T01:02:54Z

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

2015-12-08T01:01:33Z

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

2015-12-08T01:01:32Z

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}()

2015-12-08T01:01:31Z

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

2015-12-08T01:01:31Z

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

2015-12-08T01:01:19Z

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

2015-12-08T00:59:37Z

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

2015-12-06T01:58:26Z

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

2015-12-06T01:58:22Z

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

2015-12-06T01:58:05Z

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