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kernel timer API rework

In `config/kernel-timer.m4` refactor slightly to check more generally
for the new `timer_setup()` APIs, but also check the callback signature
because some kernels (notably 4.14) have the new `timer_setup()` API but
use the old callback signature. Also add a check for a `flags` member in
`struct timer_list`, which was added in 4.1-rc8.

Add compatibility shims to `include/spl/sys/timer.h` to allow using the
new timer APIs with the only two caveats being that the callback
argument type must be declared as `spl_timer_list_t` and an explicit
assignment is required to get the timer variable for the `timer_of()`
macro. So the callback would look like this:

```c
__cv_wakeup(spl_timer_list_t t)
{
        struct timer_list *tmr = (struct timer_list *)t;
	struct thing *parent = from_timer(parent, tmr,
		parent_timer_field);
	... /* do stuff with parent */
```

Make some minor changes to `spl-condvar.c` and `spl-taskq.c` to use the
new timer APIs instead of conditional code.

Reviewed-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rafael Kitover <rkitover@gmail.com>
Closes #8647
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rkitover authored and tonyhutter committed May 23, 2019
1 parent 63b88f7 commit 5d19b35c1adbebf9d7ec92b8fab073117444d54f
Showing with 103 additions and 40 deletions.
  1. +52 −11 config/kernel-timer.m4
  2. +1 −1 config/kernel.m4
  3. +25 −0 include/spl/sys/timer.h
  4. +21 −8 module/spl/spl-condvar.c
  5. +4 −20 module/spl/spl-taskq.c
@@ -1,32 +1,73 @@
dnl # 4.14-rc3 API change
dnl # https://lwn.net/Articles/735887/
dnl #
dnl # 4.15 API change
dnl # https://lkml.org/lkml/2017/11/25/90
dnl # Check if timer_list.func get passed a timer_list or an unsigned long
dnl # (older kernels). Also sanity check the from_timer() and timer_setup()
dnl # macros are available as well, since they will be used in the same newer
dnl # kernels that support the new timer_list.func signature.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_TIMER_FUNCTION_TIMER_LIST], [
AC_MSG_CHECKING([whether timer_list.function gets a timer_list])
dnl # Also check for the existance of flags in struct timer_list, they were
dnl # added in 4.1-rc8 via 0eeda71bc30d.

AC_DEFUN([ZFS_AC_KERNEL_TIMER_SETUP], [
AC_MSG_CHECKING([whether timer_setup() is available])
tmp_flags="$EXTRA_KCFLAGS"
EXTRA_KCFLAGS="-Werror"

ZFS_LINUX_TRY_COMPILE([
#include <linux/timer.h>
void task_expire(struct timer_list *tl) {}

struct my_task_timer {
struct timer_list timer;
int data;
};

void task_expire(struct timer_list *tl)
{
struct my_task_timer *task_timer = from_timer(task_timer, tl, timer);
task_timer->data = 42;
}
],[
struct my_task_timer task_timer;
timer_setup(&task_timer.timer, task_expire, 0);
],[
#ifndef from_timer
#error "No from_timer() macro"
#endif
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_KERNEL_TIMER_SETUP, 1,
[timer_setup() is available])
],[
AC_MSG_RESULT(no)
])

struct timer_list timer;
timer.function = task_expire;
timer_setup(&timer, NULL, 0);
AC_MSG_CHECKING([whether timer function expects timer_list])

ZFS_LINUX_TRY_COMPILE([
#include <linux/timer.h>
void task_expire(struct timer_list *tl) {}
],[
struct timer_list tl;
tl.function = task_expire;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_KERNEL_TIMER_FUNCTION_TIMER_LIST, 1,
[timer_list.function gets a timer_list])
],[
AC_MSG_RESULT(no)
])

AC_MSG_CHECKING([whether struct timer_list has flags])

ZFS_LINUX_TRY_COMPILE([
#include <linux/timer.h>
],[
struct timer_list tl;
tl.flags = 2;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_KERNEL_TIMER_LIST_FLAGS, 1,
[struct timer_list has a flags member])
],[
AC_MSG_RESULT(no)
])

EXTRA_KCFLAGS="$tmp_flags"
])
@@ -36,7 +36,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
ZFS_AC_KERNEL_GROUP_INFO_GID
ZFS_AC_KERNEL_WRITE
ZFS_AC_KERNEL_READ
ZFS_AC_KERNEL_TIMER_FUNCTION_TIMER_LIST
ZFS_AC_KERNEL_TIMER_SETUP
ZFS_AC_KERNEL_DECLARE_EVENT_CLASS
ZFS_AC_KERNEL_CURRENT_BIO_TAIL
ZFS_AC_KERNEL_SUPER_USER_NS
@@ -72,4 +72,29 @@ usleep_range(unsigned long min, unsigned long max)
#define USEC_TO_TICK(us) usecs_to_jiffies(us)
#define NSEC_TO_TICK(ns) usecs_to_jiffies(ns / NSEC_PER_USEC)

#ifndef from_timer
#define from_timer(var, timer, timer_field) \
container_of(timer, typeof(*var), timer_field)
#endif

#ifdef HAVE_KERNEL_TIMER_FUNCTION_TIMER_LIST
typedef struct timer_list *spl_timer_list_t;
#else
typedef unsigned long spl_timer_list_t;
#endif

#ifndef HAVE_KERNEL_TIMER_SETUP

static inline void
timer_setup(struct timer_list *timer, void (*func)(spl_timer_list_t), u32 fl)
{
#ifdef HAVE_KERNEL_TIMER_LIST_FLAGS
(timer)->flags = fl;
#endif
init_timer(timer);
setup_timer(timer, func, (spl_timer_list_t)(timer));
}

#endif /* HAVE_KERNEL_TIMER_SETUP */

#endif /* _SPL_TIMER_H */
@@ -154,26 +154,39 @@ EXPORT_SYMBOL(__cv_wait_sig);
#if defined(HAVE_IO_SCHEDULE_TIMEOUT)
#define spl_io_schedule_timeout(t) io_schedule_timeout(t)
#else

struct spl_task_timer {
struct timer_list timer;
struct task_struct *task;
};

static void
__cv_wakeup(unsigned long data)
__cv_wakeup(spl_timer_list_t t)
{
wake_up_process((struct task_struct *)data);
struct timer_list *tmr = (struct timer_list *)t;
struct spl_task_timer *task_timer = from_timer(task_timer, tmr, timer);

wake_up_process(task_timer->task);
}

static long
spl_io_schedule_timeout(long time_left)
{
long expire_time = jiffies + time_left;
struct timer_list timer;
struct spl_task_timer task_timer;
struct timer_list *timer = &task_timer.timer;

task_timer.task = current;

init_timer(&timer);
setup_timer(&timer, __cv_wakeup, (unsigned long)current);
timer.expires = expire_time;
add_timer(&timer);
timer_setup(timer, __cv_wakeup, 0);

timer->expires = expire_time;
add_timer(timer);

io_schedule();

del_timer_sync(&timer);
del_timer_sync(timer);

time_left = expire_time - jiffies;

return (time_left < 0 ? 0 : time_left);
@@ -24,6 +24,7 @@
* Solaris Porting Layer (SPL) Task Queue Implementation.
*/

#include <sys/timer.h>
#include <sys/taskq.h>
#include <sys/kmem.h>
#include <sys/tsd.h>
@@ -242,20 +243,13 @@ task_expire_impl(taskq_ent_t *t)
wake_up(&tq->tq_work_waitq);
}

#ifdef HAVE_KERNEL_TIMER_FUNCTION_TIMER_LIST
static void
task_expire(struct timer_list *tl)
task_expire(spl_timer_list_t tl)
{
taskq_ent_t *t = from_timer(t, tl, tqent_timer);
struct timer_list *tmr = (struct timer_list *)tl;
taskq_ent_t *t = from_timer(t, tmr, tqent_timer);
task_expire_impl(t);
}
#else
static void
task_expire(unsigned long data)
{
task_expire_impl((taskq_ent_t *)data);
}
#endif

/*
* Returns the lowest incomplete taskqid_t. The taskqid_t may
@@ -597,9 +591,6 @@ taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags)
t->tqent_func = func;
t->tqent_arg = arg;
t->tqent_taskq = tq;
#ifndef HAVE_KERNEL_TIMER_FUNCTION_TIMER_LIST
t->tqent_timer.data = 0;
#endif
t->tqent_timer.function = NULL;
t->tqent_timer.expires = 0;
t->tqent_birth = jiffies;
@@ -649,9 +640,6 @@ taskq_dispatch_delay(taskq_t *tq, task_func_t func, void *arg,
t->tqent_func = func;
t->tqent_arg = arg;
t->tqent_taskq = tq;
#ifndef HAVE_KERNEL_TIMER_FUNCTION_TIMER_LIST
t->tqent_timer.data = (unsigned long)t;
#endif
t->tqent_timer.function = task_expire;
t->tqent_timer.expires = (unsigned long)expire_time;
add_timer(&t->tqent_timer);
@@ -744,11 +732,7 @@ taskq_init_ent(taskq_ent_t *t)
{
spin_lock_init(&t->tqent_lock);
init_waitqueue_head(&t->tqent_waitq);
#ifdef HAVE_KERNEL_TIMER_FUNCTION_TIMER_LIST
timer_setup(&t->tqent_timer, NULL, 0);
#else
init_timer(&t->tqent_timer);
#endif
INIT_LIST_HEAD(&t->tqent_list);
t->tqent_id = 0;
t->tqent_func = NULL;

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