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Subject[PATCH 30/32] net/9p: replace p9_poll_task with a work
Date
Now that cmwq can handle high concurrency, it's more efficient to use
work than a dedicated kthread. Convert p9_poll_proc() to a work
function for p9_poll_work and make p9_pollwake() schedule it on each
poll event. The work is sync flushed on module exit.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Cc: v9fs-developer@lists.sourceforge.net
---
Lightly tested with userland server. Seems to work fine. Please feel
free to take it into the subsystem tree or simply ack - I'll route it
through the wq tree.
Thanks.

net/9p/trans_fd.c | 32 ++++++++------------------------
1 files changed, 8 insertions(+), 24 deletions(-)
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index e9f797d..a30471e 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -153,9 +153,11 @@ struct p9_conn {
unsigned long wsched;
};

+static void p9_poll_workfn(struct work_struct *work);
+
static DEFINE_SPINLOCK(p9_poll_lock);
static LIST_HEAD(p9_poll_pending_list);
-static struct task_struct *p9_poll_task;
+static DECLARE_WORK(p9_poll_work, p9_poll_workfn);

static void p9_mux_poll_stop(struct p9_conn *m)
{
@@ -515,15 +517,14 @@ static int p9_pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key)
container_of(wait, struct p9_poll_wait, wait);
struct p9_conn *m = pwait->conn;
unsigned long flags;
- DECLARE_WAITQUEUE(dummy_wait, p9_poll_task);

spin_lock_irqsave(&p9_poll_lock, flags);
if (list_empty(&m->poll_pending_link))
list_add_tail(&m->poll_pending_link, &p9_poll_pending_list);
spin_unlock_irqrestore(&p9_poll_lock, flags);

- /* perform the default wake up operation */
- return default_wake_function(&dummy_wait, mode, sync, key);
+ schedule_work(&p9_poll_work);
+ return 1;
}

/**
@@ -1046,12 +1047,12 @@ static struct p9_trans_module p9_fd_trans = {
*
*/

-static int p9_poll_proc(void *a)
+static void p9_poll_workfn(struct work_struct *work)
{
unsigned long flags;

P9_DPRINTK(P9_DEBUG_TRANS, "start %p\n", current);
- repeat:
+
spin_lock_irqsave(&p9_poll_lock, flags);
while (!list_empty(&p9_poll_pending_list)) {
struct p9_conn *conn = list_first_entry(&p9_poll_pending_list,
@@ -1066,28 +1067,11 @@ static int p9_poll_proc(void *a)
}
spin_unlock_irqrestore(&p9_poll_lock, flags);

- set_current_state(TASK_INTERRUPTIBLE);
- if (list_empty(&p9_poll_pending_list)) {
- P9_DPRINTK(P9_DEBUG_TRANS, "sleeping...\n");
- schedule();
- }
- __set_current_state(TASK_RUNNING);
-
- if (!kthread_should_stop())
- goto repeat;
-
P9_DPRINTK(P9_DEBUG_TRANS, "finish\n");
- return 0;
}

int p9_trans_fd_init(void)
{
- p9_poll_task = kthread_run(p9_poll_proc, NULL, "v9fs-poll");
- if (IS_ERR(p9_poll_task)) {
- printk(KERN_WARNING "v9fs: mux: creating poll task failed\n");
- return PTR_ERR(p9_poll_task);
- }
-
v9fs_register_trans(&p9_tcp_trans);
v9fs_register_trans(&p9_unix_trans);
v9fs_register_trans(&p9_fd_trans);
@@ -1097,7 +1081,7 @@ int p9_trans_fd_init(void)

void p9_trans_fd_exit(void)
{
- kthread_stop(p9_poll_task);
+ flush_work_sync(&p9_poll_work);
v9fs_unregister_trans(&p9_tcp_trans);
v9fs_unregister_trans(&p9_unix_trans);
v9fs_unregister_trans(&p9_fd_trans);
--
1.7.1


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