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Groups > linux.kernel > #1379003
| From | Petr Mladek <pmladek@suse.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH v6 16/20] IB/fmr_pool: Convert the cleanup thread into kthread worker API |
| Date | 2016-04-14 17:20 +0200 |
| Message-ID | <rnRdN-3Ro-45@gated-at.bofh.it> (permalink) |
| References | <rnRdL-3Ro-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Kthreads are currently implemented as an infinite loop. Each
has its own variant of checks for terminating, freezing,
awakening. In many cases it is unclear to say in which state
it is and sometimes it is done a wrong way.
The plan is to convert kthreads into kthread_worker or workqueues
API. It allows to split the functionality into separate operations.
It helps to make a better structure. Also it defines a clean state
where no locks are taken, IRQs blocked, the kthread might sleep
or even be safely migrated.
The kthread worker API is useful when we want to have a dedicated
single thread for the work. It helps to make sure that it is
available when needed. Also it allows a better control, e.g.
define a scheduling priority.
This patch converts the frm_pool kthread into the kthread worker
API because I am not sure how busy the thread is. It is well
possible that it does not need a dedicated kthread and workqueues
would be perfectly fine. Well, the conversion between kthread
worker API and workqueues is pretty trivial.
The patch moves one iteration from the kthread into the work function.
It preserves the check for a spurious queuing (wake up). Then it
processes one request. Finally, it re-queues itself if more requests
are pending.
Otherwise, wake_up_process() is replaced by queuing the work.
Important: The change is only compile tested. I did not find an easy
way how to check it in a real life.
Signed-off-by: Petr Mladek <pmladek@suse.com>
CC: Doug Ledford <dledford@redhat.com>
CC: Sean Hefty <sean.hefty@intel.com>
CC: Hal Rosenstock <hal.rosenstock@gmail.com>
CC: linux-rdma@vger.kernel.org
---
drivers/infiniband/core/fmr_pool.c | 54 ++++++++++++++++++--------------------
1 file changed, 25 insertions(+), 29 deletions(-)
diff --git a/drivers/infiniband/core/fmr_pool.c b/drivers/infiniband/core/fmr_pool.c
index cdbb1f1a6d97..571089ba3a72 100644
--- a/drivers/infiniband/core/fmr_pool.c
+++ b/drivers/infiniband/core/fmr_pool.c
@@ -96,7 +96,8 @@ struct ib_fmr_pool {
void * arg);
void *flush_arg;
- struct task_struct *thread;
+ struct kthread_worker *worker;
+ struct kthread_work work;
atomic_t req_ser;
atomic_t flush_ser;
@@ -174,29 +175,26 @@ static void ib_fmr_batch_release(struct ib_fmr_pool *pool)
spin_unlock_irq(&pool->pool_lock);
}
-static int ib_fmr_cleanup_thread(void *pool_ptr)
+static void ib_fmr_cleanup_func(struct kthread_work *work)
{
- struct ib_fmr_pool *pool = pool_ptr;
+ struct ib_fmr_pool *pool = container_of(work, struct ib_fmr_pool, work);
- do {
- if (atomic_read(&pool->flush_ser) - atomic_read(&pool->req_ser) < 0) {
- ib_fmr_batch_release(pool);
-
- atomic_inc(&pool->flush_ser);
- wake_up_interruptible(&pool->force_wait);
+ /*
+ * The same request might be queued twice when it appears and
+ * by re-queuing from this work.
+ */
+ if (atomic_read(&pool->flush_ser) - atomic_read(&pool->req_ser) >= 0)
+ return;
- if (pool->flush_function)
- pool->flush_function(pool, pool->flush_arg);
- }
+ ib_fmr_batch_release(pool);
+ atomic_inc(&pool->flush_ser);
+ wake_up_interruptible(&pool->force_wait);
- set_current_state(TASK_INTERRUPTIBLE);
- if (atomic_read(&pool->flush_ser) - atomic_read(&pool->req_ser) >= 0 &&
- !kthread_should_stop())
- schedule();
- __set_current_state(TASK_RUNNING);
- } while (!kthread_should_stop());
+ if (pool->flush_function)
+ pool->flush_function(pool, pool->flush_arg);
- return 0;
+ if (atomic_read(&pool->flush_ser) - atomic_read(&pool->req_ser) < 0)
+ queue_kthread_work(pool->worker, &pool->work);
}
/**
@@ -266,15 +264,13 @@ struct ib_fmr_pool *ib_create_fmr_pool(struct ib_pd *pd,
atomic_set(&pool->flush_ser, 0);
init_waitqueue_head(&pool->force_wait);
- pool->thread = kthread_run(ib_fmr_cleanup_thread,
- pool,
- "ib_fmr(%s)",
- device->name);
- if (IS_ERR(pool->thread)) {
- pr_warn(PFX "couldn't start cleanup thread\n");
- ret = PTR_ERR(pool->thread);
+ pool->worker = create_kthread_worker(0, "ib_fmr(%s)", device->name);
+ if (IS_ERR(pool->worker)) {
+ pr_warn(PFX "couldn't start cleanup kthread worker\n");
+ ret = PTR_ERR(pool->worker);
goto out_free_pool;
}
+ init_kthread_work(&pool->work, ib_fmr_cleanup_func);
{
struct ib_pool_fmr *fmr;
@@ -339,7 +335,7 @@ void ib_destroy_fmr_pool(struct ib_fmr_pool *pool)
LIST_HEAD(fmr_list);
int i;
- kthread_stop(pool->thread);
+ destroy_kthread_worker(pool->worker);
ib_fmr_batch_release(pool);
i = 0;
@@ -389,7 +385,7 @@ int ib_flush_fmr_pool(struct ib_fmr_pool *pool)
spin_unlock_irq(&pool->pool_lock);
serial = atomic_inc_return(&pool->req_ser);
- wake_up_process(pool->thread);
+ queue_kthread_work(pool->worker, &pool->work);
if (wait_event_interruptible(pool->force_wait,
atomic_read(&pool->flush_ser) - serial >= 0))
@@ -503,7 +499,7 @@ int ib_fmr_pool_unmap(struct ib_pool_fmr *fmr)
list_add_tail(&fmr->list, &pool->dirty_list);
if (++pool->dirty_len >= pool->dirty_watermark) {
atomic_inc(&pool->req_ser);
- wake_up_process(pool->thread);
+ queue_kthread_work(pool->worker, &pool->work);
}
}
}
--
1.8.5.6
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[PATCH v6 00/20] kthread: Use kthread worker API more widely Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 18/20] memstick/r592: convert r592_io kthread into kthread worker API Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 15/20] ipmi: Convert kipmi kthread into kthread worker API Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 07/20] kthread: Initial support for delayed kthread work Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 19/20] thermal/intel_powerclamp: Remove duplicated code that starts the kthread Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 16/20] IB/fmr_pool: Convert the cleanup thread into kthread worker API Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 12/20] ring_buffer: Convert benchmark kthreads into kthread worker API Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 20/20] thermal/intel_powerclamp: Convert the kthread to kthread worker API Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 02/20] kthread: Allow to call __kthread_create_on_node() with va_list args Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 03/20] kthread: Add create_kthread_worker*() Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 11/20] mm/huge_page: Convert khugepaged() into kthread worker API Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 17/20] memstick/r592: Better synchronize debug messages in r592_io kthread Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 05/20] kthread: Add destroy_kthread_worker() Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 13/20] hung_task: Convert hungtaskd into kthread worker API Petr Mladek <pmladek@suse.com> - 2016-04-14 17:20 +0200 [PATCH v6 01/20] kthread/smpboot: Do not park in kthread_create_on_cpu() Petr Mladek <pmladek@suse.com> - 2016-04-14 17:30 +0200 [PATCH v6 06/20] kthread: Detect when a kthread work is used by more workers Petr Mladek <pmladek@suse.com> - 2016-04-14 17:30 +0200 [PATCH v6 08/20] kthread: Allow to cancel kthread work Petr Mladek <pmladek@suse.com> - 2016-04-14 17:30 +0200 [PATCH v6 04/20] kthread: Add drain_kthread_worker() Petr Mladek <pmladek@suse.com> - 2016-04-14 17:30 +0200
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