linux-toradex.git/kernel/rcu/srcu.c, branch v4.9.62

rcu: Add rcu_normal kernel parameter to suppress expediting

2015-12-04T20:26:53+00:00

Although expedited grace periods can be quite useful, and although their
OS jitter has been greatly reduced, they can still pose problems for
extreme real-time workloads.  This commit therefore adds a rcu_normal
kernel boot parameter (which can also be manipulated via sysfs)
to suppress expedited grace periods, that is, to treat requests for
expedited grace periods as if they were requests for normal grace periods.
If both rcu_expedited and rcu_normal are specified, rcu_normal wins.
This means that if you are relying on expedited grace periods to speed up
boot, you will want to specify rcu_expedited on the kernel command line,
and then specify rcu_normal via sysfs once boot completes.

Signed-off-by: Paul E. McKenney

rcu: Move preemption disabling out of __srcu_read_lock()

2015-10-06T18:15:43+00:00

Currently, __srcu_read_lock() cannot be invoked from restricted
environments because it contains calls to preempt_disable() and
preempt_enable(), both of which can invoke lockdep, which is a bad
idea in some restricted execution modes.  This commit therefore moves
the preempt_disable() and preempt_enable() from __srcu_read_lock()
to srcu_read_lock().  It also inserts the preempt_disable() and
preempt_enable() around the call to __srcu_read_lock() in do_exit().

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

rcu: Use rcu_callback_t in call_rcu*() and friends

2015-10-06T18:08:05+00:00

As we now have rcu_callback_t typedefs as the type of rcu callbacks, we
should use it in call_rcu*() and friends as the type of parameters. This
could save us a few lines of code and make it clear which function
requires an rcu callbacks rather than other callbacks as its argument.

Besides, this can also help cscope to generate a better database for
code reading.

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

rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()

2015-07-22T22:27:32+00:00

This commit renames rcu_lockdep_assert() to RCU_LOCKDEP_WARN() for
consistency with the WARN() series of macros.  This also requires
inverting the sense of the conditional, which this commit also does.

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

rcu: Change return type to bool

2015-07-15T21:43:53+00:00

Type-checking coccinelle spatches are being used to locate type mismatches
between function signatures and return values in this case this produced:
./kernel/rcu/srcu.c:271 WARNING: return of wrong type
        int != unsigned long,

srcu_readers_active() returns an int that is the sum of per_cpu unsigned
long but the only user is cleanup_srcu_struct() which is using it as a
boolean (condition) to see if there is any readers rather than actually
using the approximate number of readers. The theoretically possible
unsigned long overflow case does not need to be handled explicitly - if
we had 4G++ readers then something else went wrong a long time ago.

proposal: change the return type to boolean. The function name is left
          unchanged as it fits the naming expectation for a boolean.

patch was compile tested for x86_64_defconfig (implies CONFIG_SRCU=y)

patch is against 4.1-rc5 (localversion-next is -next-20150525)

Signed-off-by: Nicholas Mc Guire 
Signed-off-by: Paul E. McKenney

rcu: Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE()

2015-05-27T19:56:15+00:00

This commit moves from the old ACCESS_ONCE() API to the new READ_ONCE()
and WRITE_ONCE() APIs.

Signed-off-by: Paul E. McKenney 
[ paulmck:  Updated to include kernel/torture.c as suggested by Jason Low. ]

Merge branches 'doc.2015.02.26a', 'earlycb.2015.03.03a', 'fixes.2015.03.03a', 'gpexp.2015.02.26a', 'hotplug.2015.03.20a', 'sysidle.2015.02.26b' and 'tiny.2015.02.26a' into HEAD

2015-03-20T15:31:01+00:00

doc.2015.02.26a:  Documentation changes
earlycb.2015.03.03a:  Permit early-boot RCU callbacks
fixes.2015.03.03a:  Miscellaneous fixes
gpexp.2015.02.26a:  In-kernel expediting of normal grace periods
hotplug.2015.03.20a:  CPU hotplug fixes
sysidle.2015.02.26b:  NO_HZ_FULL_SYSIDLE fixes
tiny.2015.02.26a:  TINY_RCU fixes

rcu: Update from rcu_expedited variable to rcu_gp_is_expedited()

2015-02-26T20:03:01+00:00

This commit updates open-coded tests of the rcu_expedited variable
to instead use rcu_gp_is_expedited().

Signed-off-by: Paul E. McKenney

rcu: Consolidate rcu_synchronize and wakeme_after_rcu()

2015-02-26T01:03:03+00:00

There are currently duplicate identical definitions of the
rcu_synchronize() structure and the wakeme_after_rcu() function.
Thie commit therefore consolidates them.

Signed-off-by: Paul E. McKenney

rcu: Expand SRCU ->completed to 64 bits

2015-01-06T19:04:26+00:00

When rcutorture used only the low-order 32 bits of the grace-period
number, it was not a problem for SRCU to use a 32-bit completed field.
However, rcutorture now uses the full 64 bits on 64-bit systems, so
this commit converts SRCU's ->completed field to unsigned long so as to
provide 64 bits on 64-bit systems.

Signed-off-by: Paul E. McKenney