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drivers/tty: Compute 'current' directly 

This patch effectively replaces the tsk pointer dereference
(which is obviously == current), to directly use get_current()
macro. This is to make the removal of setting foreign task
states smoother and painfully obvious. Performance win on some
archs such as x86-64 and ppc64 -- arm64 is no longer an issue.

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: mark.rutland@arm.com
Link: http://lkml.kernel.org/r/1483479794-14013-3-git-send-email-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Davidlohr Bueso 2017-01-03 13:43:12 -08:00 committed by Ingo Molnar
parent 0039962a14
commit 5376f2e722
1 changed files with 8 additions and 10 deletions
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18
drivers/tty/tty_ldsem.c
View File

@ -200,7 +200,6 @@ static struct ld_semaphore __sched *
down_read_failed(struct ld_semaphore *sem, long count, long timeout)
{
struct ldsem_waiter waiter;
struct task_struct *tsk = current;
long adjust = -LDSEM_ACTIVE_BIAS + LDSEM_WAIT_BIAS;
/* set up my own style of waitqueue */
@ -221,8 +220,8 @@ down_read_failed(struct ld_semaphore *sem, long count, long timeout)
list_add_tail(&waiter.list, &sem->read_wait);
sem->wait_readers++;
waiter.task = tsk;
get_task_struct(tsk);
waiter.task = current;
get_task_struct(current);
/* if there are no active locks, wake the new lock owner(s) */
if ((count & LDSEM_ACTIVE_MASK) == 0)
@ -232,7 +231,7 @@ down_read_failed(struct ld_semaphore *sem, long count, long timeout)
/* wait to be given the lock */
for (;;) {
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
set_task_state(current, TASK_UNINTERRUPTIBLE);
if (!waiter.task)
break;
@ -241,7 +240,7 @@ down_read_failed(struct ld_semaphore *sem, long count, long timeout)
timeout = schedule_timeout(timeout);
}
__set_task_state(tsk, TASK_RUNNING);
__set_task_state(current, TASK_RUNNING);
if (!timeout) {
/* lock timed out but check if this task was just
@ -268,7 +267,6 @@ static struct ld_semaphore __sched *
down_write_failed(struct ld_semaphore *sem, long count, long timeout)
{
struct ldsem_waiter waiter;
struct task_struct *tsk = current;
long adjust = -LDSEM_ACTIVE_BIAS;
int locked = 0;
@ -289,16 +287,16 @@ down_write_failed(struct ld_semaphore *sem, long count, long timeout)
list_add_tail(&waiter.list, &sem->write_wait);
waiter.task = tsk;
waiter.task = current;
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
set_task_state(current, TASK_UNINTERRUPTIBLE);
for (;;) {
if (!timeout)
break;
raw_spin_unlock_irq(&sem->wait_lock);
timeout = schedule_timeout(timeout);
raw_spin_lock_irq(&sem->wait_lock);
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
set_task_state(current, TASK_UNINTERRUPTIBLE);
locked = writer_trylock(sem);
if (locked)
break;
@ -309,7 +307,7 @@ down_write_failed(struct ld_semaphore *sem, long count, long timeout)
list_del(&waiter.list);
raw_spin_unlock_irq(&sem->wait_lock);
__set_task_state(tsk, TASK_RUNNING);
__set_task_state(current, TASK_RUNNING);
/* lock wait may have timed out */
if (!locked)