cpufreq: Resolve CPUFREQ_NOTIFY issue

When the cpufreq_stat receives the frequency policy notification,
it checks if the frequency table and stats table are present for the cpu.
If both are present, it returns with -EBUSY error to the notification.
Due to this, none of the other registered modules receive this
notification.

If the stat table and sysfs nodes are already created, return 0 instead
of returning EBUSY error.

Change-Id: I1fd4a46e6a65edfc6253c4271288f10912ae2ad7
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>
random: fix accounting race condition with lockless irq entropy_count update

Commit 902c098a3663 ("random: use lockless techniques in the interrupt
path") turned IRQ path from being spinlock protected into lockless
cmpxchg-retry update.

That commit removed r->lock serialization between crediting entropy bits
from IRQ context and accounting when extracting entropy on userspace
read path, but didn't turn the r->entropy_count reads/updates in
account() to use cmpxchg as well.

It has been observed, that under certain circumstances this leads to
read() on /dev/urandom to return 0 (EOF), as r->entropy_count gets
corrupted and becomes negative, which in turn results in propagating 0
all the way from account() to the actual read() call.

Convert the accounting code to be the proper lockless counterpart of
what has been partially done by 902c098a3663.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Greg KH <greg@kroah.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
block: Remove "requeuing urgent req" error messages

It is possible for URGENT request to be requeued/reinserted if it was
fetched during the creation of a packed list. This end case is rare and is
not handled at the moment.
This patch changes the messages notifying of the above to debug level
(instead of error) in order to clear the dmesg log.

Change-Id: Ie8bc067e61559a6f702077b95c5dbcc426404232
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
sched: Set MC (multi-core) sched domain's busy_factor attribute to 1

busy_factor attribute of a scheduler domain causes busy CPUs (CPUs
that are not idle) to load balance less frequently in that domain,
which could impact performance by increasing scheduling latency for
tasks.

As an example, consider MC scheduler domain's attribute values of
max_interval = 4ms and busy_factor = 64. Further consider
max_load_balance_interval = 100 (HZ/10). In this case, a non-idle CPU
could put off load balance check in MC domain by 100ms. This
effectively means that a CPU running a single task in its queue could
fail to notice increased load on another CPU (that is in same MC
domain) for upto 100ms, before picking up load from the overloaded
CPU. Needless to say, this leads to increased scheduling latency for
tasks, affecting performance adversely.

By setting MC domain's busy_factor value to 1, we limit maximum
interval that busy CPU can put off load balance checks to 4ms
(effectively 10ms, given HZ value of 100).

Change-Id: Id45869d06f5556ea8eec602b65c2ffd2143fe060
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
lib: spinlock_debug: Avoid livelock in do_raw_spin_lock