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Date: Thu, 17 Jan 2019 23:41:35 +0100
From: Hugo Lefeuvre <hle@....eu.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Greg Hartman <ghartman@...gle.com>,
Alistair Strachan <strachan@...gle.com>,
Arve Hjønnevåg <arve@...roid.com>,
Todd Kjos <tkjos@...roid.com>,
Martijn Coenen <maco@...roid.com>,
Joel Fernandes <joel@...lfernandes.org>,
Christian Brauner <christian@...uner.io>,
Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: [PATCH] sched/wait: introduce wait_event_freezable_hrtimeout
introduce wait_event_freezable_hrtimeout, an interruptible and freezable
version of wait_event_hrtimeout.
simplify handle_vsoc_cond_wait (drivers/staging/android/vsoc.c) using this
newly added helper and remove useless includes.
Signed-off-by: Hugo Lefeuvre <hle@....eu.com>
---
drivers/staging/android/vsoc.c | 69 +++++-----------------------------
include/linux/wait.h | 25 ++++++++++--
2 files changed, 31 insertions(+), 63 deletions(-)
diff --git a/drivers/staging/android/vsoc.c b/drivers/staging/android/vsoc.c
index 22571abcaa4e..7e620e69f39d 100644
--- a/drivers/staging/android/vsoc.c
+++ b/drivers/staging/android/vsoc.c
@@ -17,7 +17,6 @@
*/
#include <linux/dma-mapping.h>
-#include <linux/freezer.h>
#include <linux/futex.h>
#include <linux/init.h>
#include <linux/kernel.h>
@@ -29,7 +28,6 @@
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <linux/interrupt.h>
-#include <linux/mutex.h>
#include <linux/cdev.h>
#include <linux/file.h>
#include "uapi/vsoc_shm.h"
@@ -401,7 +399,6 @@ static int handle_vsoc_cond_wait(struct file *filp, struct vsoc_cond_wait *arg)
DEFINE_WAIT(wait);
u32 region_number = iminor(file_inode(filp));
struct vsoc_region_data *data = vsoc_dev.regions_data + region_number;
- struct hrtimer_sleeper timeout, *to = NULL;
int ret = 0;
struct vsoc_device_region *region_p = vsoc_region_from_filep(filp);
atomic_t *address = NULL;
@@ -420,69 +417,23 @@ static int handle_vsoc_cond_wait(struct file *filp, struct vsoc_cond_wait *arg)
/* Ensure that the type of wait is valid */
switch (arg->wait_type) {
case VSOC_WAIT_IF_EQUAL:
+ ret = wait_event_freezable(data->futex_wait_queue,
+ arg->wakes++ &&
+ atomic_read(address) != arg->value);
break;
case VSOC_WAIT_IF_EQUAL_TIMEOUT:
- to = &timeout;
- break;
- default:
- return -EINVAL;
- }
-
- if (to) {
- /* Copy the user-supplied timesec into the kernel structure.
- * We do things this way to flatten differences between 32 bit
- * and 64 bit timespecs.
- */
if (arg->wake_time_nsec >= NSEC_PER_SEC)
return -EINVAL;
wake_time = ktime_set(arg->wake_time_sec, arg->wake_time_nsec);
-
- hrtimer_init_on_stack(&to->timer, CLOCK_MONOTONIC,
- HRTIMER_MODE_ABS);
- hrtimer_set_expires_range_ns(&to->timer, wake_time,
- current->timer_slack_ns);
-
- hrtimer_init_sleeper(to, current);
+ ret = wait_event_freezable_hrtimeout(data->futex_wait_queue,
+ arg->wakes++ &&
+ atomic_read(address) != arg->value,
+ wake_time);
+ break;
+ default:
+ return -EINVAL;
}
- while (1) {
- prepare_to_wait(&data->futex_wait_queue, &wait,
- TASK_INTERRUPTIBLE);
- /*
- * Check the sentinel value after prepare_to_wait. If the value
- * changes after this check the writer will call signal,
- * changing the task state from INTERRUPTIBLE to RUNNING. That
- * will ensure that schedule() will eventually schedule this
- * task.
- */
- if (atomic_read(address) != arg->value) {
- ret = 0;
- break;
- }
- if (to) {
- hrtimer_start_expires(&to->timer, HRTIMER_MODE_ABS);
- if (likely(to->task))
- freezable_schedule();
- hrtimer_cancel(&to->timer);
- if (!to->task) {
- ret = -ETIMEDOUT;
- break;
- }
- } else {
- freezable_schedule();
- }
- /* Count the number of times that we woke up. This is useful
- * for unit testing.
- */
- ++arg->wakes;
- if (signal_pending(current)) {
- ret = -EINTR;
- break;
- }
- }
- finish_wait(&data->futex_wait_queue, &wait);
- if (to)
- destroy_hrtimer_on_stack(&to->timer);
return ret;
}
diff --git a/include/linux/wait.h b/include/linux/wait.h
index ed7c122cb31f..13a454884f8b 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -483,7 +483,7 @@ do { \
__ret; \
})
-#define __wait_event_hrtimeout(wq_head, condition, timeout, state) \
+#define __wait_event_hrtimeout(wq_head, condition, timeout, state, cmd) \
({ \
int __ret = 0; \
struct hrtimer_sleeper __t; \
@@ -500,7 +500,7 @@ do { \
__ret = -ETIME; \
break; \
} \
- schedule()); \
+ cmd); \
\
hrtimer_cancel(&__t.timer); \
destroy_hrtimer_on_stack(&__t.timer); \
@@ -529,7 +529,23 @@ do { \
might_sleep(); \
if (!(condition)) \
__ret = __wait_event_hrtimeout(wq_head, condition, timeout, \
- TASK_UNINTERRUPTIBLE); \
+ TASK_UNINTERRUPTIBLE, \
+ schedule()); \
+ __ret; \
+})
+
+/*
+ * like wait_event_hrtimeout() -- except it uses TASK_INTERRUPTIBLE to avoid
+ * increasing load and is freezable.
+ */
+#define wait_event_freezable_hrtimeout(wq_head, condition, timeout) \
+({ \
+ int __ret = 0; \
+ might_sleep(); \
+ if (!(condition)) \
+ __ret = __wait_event_hrtimeout(wq_head, condition, timeout, \
+ TASK_INTERRUPTIBLE, \
+ freezable_schedule()); \
__ret; \
})
@@ -555,7 +571,8 @@ do { \
might_sleep(); \
if (!(condition)) \
__ret = __wait_event_hrtimeout(wq, condition, timeout, \
- TASK_INTERRUPTIBLE); \
+ TASK_INTERRUPTIBLE, \
+ schedule()); \
__ret; \
})
--
2.20.1
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