linux-toradex.git/include/linux/rcupdate.h, branch v5.1-rc4

Merge branches 'doc.2019.01.26a', 'fixes.2019.01.26a', 'sil.2019.01.26a', 'spdx.2019.02.09a', 'srcu.2019.01.26a' and 'torture.2019.01.26a' into HEAD

2019-02-09T16:47:52+00:00

doc.2019.01.26a:  Documentation updates.
fixes.2019.01.26a:  Miscellaneous fixes.
sil.2019.01.26a:  Removal of a few more spin_is_locked() instances.
spdx.2019.02.09a:  Add SPDX identifiers to RCU files
srcu.2019.01.26a:  SRCU updates.
torture.2019.01.26a: Torture-test updates.

linux/rcupdate: Convert to SPDX license identifier

2019-02-09T16:44:37+00:00

Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.

Signed-off-by: Paul E. McKenney 
[ paulmck: Update .h SPDX format per Joe Perches. ]
Reviewed-by: Thomas Gleixner

rcu: Add sparse check to rcu_assign_pointer()

2019-01-25T23:35:24+00:00

The rcu_assign_pointer() function currently doesn't do any sparse checking
on the assigned-to pointer.  So its possible that a pointer that is
not __rcu annotated is assigned with rcu_assign_pointer without sparse
complaints.  Because rcu_dereference() already does such checking,
this commit makes rcu_assign_pointer() to do the same. The extra
error could be helpful in cases where an RCU pointer is assigned with
rcu_assign_pointer() but not annotated with __rcu.

This doesn't generate any code in the normal case because __CHECKER__ is
defined only in the context of sparse.

This commit also renames rcu_dereference_sparse() to rcu_check_parse()
since the checking now happens not only during derereferencing but also
during assignment.

Test: Introduced an rcu_assign_pointer in code and checked the output of
sparse with and without this change. The change correctly causes sparse
to throw an error.

Signed-off-by: Joel Fernandes (Google) 
Signed-off-by: Paul E. McKenney

rcu: Rename rcu_check_callbacks() to rcu_sched_clock_irq()

2019-01-25T23:35:21+00:00

The name rcu_check_callbacks() arguably made sense back in the early
2000s when RCU was quite a bit simpler than it is today, but it has
become quite misleading, especially with the advent of dyntick-idle
and NO_HZ_FULL.  The rcu_check_callbacks() function is RCU's hook into
the scheduling-clock interrupt, and is now but one of many ways that
callbacks get promoted to invocable state.

This commit therefore changes the name to rcu_sched_clock_irq(),
which is the same number of characters and clearly indicates this
function's relation to the rest of the Linux kernel.  In addition, for
the sake of consistency, rcu_flavor_check_callbacks() is also renamed
to rcu_flavor_sched_clock_irq().

While in the area, the header comments for both functions are reworked.

Signed-off-by: Paul E. McKenney

rcu: Docbook for rcu_head_init() and rcu_head_after_call_rcu()

2019-01-25T23:35:19+00:00

This commit adds the missing asterisks required to make Sphinx pick up
the current header comments for these two functions.

Signed-off-by: Paul E. McKenney

rcu: Remove wrapper definitions for obsolete RCU update functions

2019-01-25T23:28:31+00:00

None of synchronize_rcu_bh, synchronize_rcu_bh_expedited, call_rcu_bh,
rcu_barrier_bh, synchronize_sched, synchronize_sched_expedited,
call_rcu_sched, rcu_barrier_sched, get_state_synchronize_sched, and
cond_synchronize_sched are actually used.  This commit therefore removes
their trivial wrapper-function definitions.

Signed-off-by: Paul E. McKenney

rcu: Provide functions for determining if call_rcu() has been invoked

2018-08-30T23:03:42+00:00

This commit adds rcu_head_init() and rcu_head_after_call_rcu() functions
to help RCU users detect when another CPU has passed the specified
rcu_head structure and function to call_rcu().  The rcu_head_init()
should be invoked before making the structure visible to RCU readers,
and then the rcu_head_after_call_rcu() may be invoked from within
an RCU read-side critical section on an rcu_head structure that
was obtained during a traversal of the data structure in question.
The rcu_head_after_call_rcu() function will return true if the rcu_head
structure has already been passed (with the specified function) to
call_rcu(), otherwise it will return false.

If rcu_head_init() has not been invoked on the rcu_head structure
or if the rcu_head (AKA callback) has already been invoked, then
rcu_head_after_call_rcu() will do WARN_ON_ONCE().

Reported-by: NeilBrown 
Signed-off-by: Paul E. McKenney 
[ paulmck: Apply neilb naming feedback. ]

rcu: Remove !PREEMPT code from rcu_note_voluntary_context_switch()

2018-08-30T23:03:36+00:00

Because RCU-tasks exists only in PREEMPT kernels and because RCU-sched
no longer exists in PREEMPT kernels, it is no longer necessary for the
rcu_note_voluntary_context_switch() macro to do anything for !PREEMPT
kernels.  This commit therefore removes !PREEMPT-related code from
this macro, namely, the rcu_all_qs().

Signed-off-by: Paul E. McKenney

rcu: Clean up flavor-related definitions and comments in rcupdate.h

2018-08-30T23:03:31+00:00

Signed-off-by: Paul E. McKenney

rcu: Consolidate RCU-sched update-side function definitions

2018-08-30T23:03:26+00:00

This commit saves a few lines by consolidating the RCU-sched function
definitions at the end of include/linux/rcupdate.h.  This consolidation
also makes it easier to remove them all when the time comes.

Signed-off-by: Paul E. McKenney