BUG: headers with BUG/BUG_ON etc. need linux/bug.h

If a header file is making use of BUG, BUG_ON, BUILD_BUG_ON, or any
other BUG variant in a static inline (i.e. not in a #define) then
that header really should be including <linux/bug.h> and not just
expecting it to be implicitly present.

We can make this change risk-free, since if the files using these
headers didn't have exposure to linux/bug.h already, they would have
been causing compile failures/warnings.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
consolidate WARN_...ONCE() static variables

Due to the alignment of following variables, these typically consume
more than just the single byte that 'bool' requires, and as there are a
few hundred instances, the cache pollution (not so much the waste of
memory) sums up.  Put these variables into their own section, outside of
any half way frequently used memory range.

Do the same also to the __warned variable of rcu_lockdep_assert().
(Don't, however, include the ones used by printk_once() and alike, as
they can potentially be hot.)

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
rcu: Make __kfree_rcu() less dependent on compiler choices

Currently, __kfree_rcu() is implemented as an inline function, and
contains a BUILD_BUG_ON() that malfunctions if __kfree_rcu() is compiled
as an out-of-line function.  Unfortunately, there are compiler settings
(e.g., -O0) that can result in __kfree_rcu() being compiled out of line,
resulting in annoying build breakage.  This commit therefore converts
both __kfree_rcu() and __is_kfree_rcu_offset() from inline functions to
macros to prevent such misbehavior on the part of the compiler.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
rcu: Make exit_rcu() more precise and consolidate

When running preemptible RCU, if a task exits in an RCU read-side
critical section having blocked within that same RCU read-side critical
section, the task must be removed from the list of tasks blocking a
grace period (perhaps the current grace period, perhaps the next grace
period, depending on timing).  The exit() path invokes exit_rcu() to
do this cleanup.

However, the current implementation of exit_rcu() needlessly does the
cleanup even if the task did not block within the current RCU read-side
critical section, which wastes time and needlessly increases the size
of the state space.  Fix this by only doing the cleanup if the current
task is actually on the list of tasks blocking some grace period.

While we are at it, consolidate the two identical exit_rcu() functions
into a single function.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Linus Torvalds <torvalds@linux-foundation.org>
rcu: Add a gcc-style structure initializer for RCU pointers

RCU_INIT_POINTER() returns a value that is never used, and which should
be abolished due to terminal ugliness:

	q = RCU_INIT_POINTER(global_p, p);

However, there are two uses that cannot be handled by a do-while
formulation because they do gcc-style initialization:

	RCU_INIT_POINTER(.real_cred, &init_cred),
	RCU_INIT_POINTER(.cred, &init_cred),

This usage is clever, but not necessarily the nicest approach.
This commit therefore creates an RCU_POINTER_INITIALIZER() macro that
is specifically designed for gcc-style initialization.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: David Howells <dhowells@redhat.com>
rcu: Consolidate tree/tiny __rcu_read_{,un}lock() implementations

The CONFIG_TREE_PREEMPT_RCU and CONFIG_TINY_PREEMPT_RCU versions of
__rcu_read_lock() and __rcu_read_unlock() are identical, so this commit
consolidates them into kernel/rcupdate.h.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
rcu: Remove function versions of __kfree_rcu and __is_kfree_rcu_offset

Commit d8169d4c (Make __kfree_rcu() less dependent on compiler choices)
added cpp macro versions of __kfree_rcu() and __is_kfree_rcu_offset(),
but failed to remove the old inline-function versions.  This commit does
this cleanup.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cleanup, it's was merged with older commit.
rcu: Fix qlen_lazy breakage

Commit d8169d4c (Make __kfree_rcu() less dependent on compiler choices)
created a macro out of an inline function in order to avoid build
breakage for certain combinations of gcc flags.  Unfortunately, it also
converted a kfree_call_rcu() to a call_rcu(), which made the rcu_data
structure's ->qlen_lazy field lose counts.  This commit therefore changes
the call_rcu() back to kfree_call_rcu().

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
rcu: Fix broken strings in RCU's source code. + file PULL!

Although the C language allows you to break strings across lines, doing
this makes it hard for people to find the Linux kernel code corresponding
to a given console message.  This commit therefore fixes broken strings
throughout RCU's source code.

Suggested-by: Josh Triplett <josh@joshtriplett.org>
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Pulled from 3.7.Y:

kernel/rcutorture.c
kernel/rcutree_trace.c
include/trace/events/rcu.h