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Subject[PATCH] CMWQ: Set workqueue name before we process one work.
Date
Now in CMWQ, workqueue threads are named as 'kworker/*'. So it is
a little boring to see in the 'top'(below) and actually it isn't
meaningful for the users.
12606 root 20 0 0 0 0 S 2 0.0 0:03.22 kworker/u:0
12607 root 20 0 0 0 0 S 1 0.0 0:03.69 kworker/u:4
So this patch just try to set the proper workqueue name if it does
exist. Yes, workqueue now is a thread pool and the data may be not
accurate but I think it is better(below) than the 'kworker*' stuff.
And if there is something block the workqueue, we can find the caller
easily.
12606 root 20 0 0 0 0 D 2 0.0 0:02.90 dlm_wq
12607 root 20 0 0 0 0 D 0 0.0 0:03.21 ocfs2_wq

What's more, in ocfs2, we sometimes want to print some debug info in
the system log and we use 'current->comm' to print the thread and this
change also does help.

The only thing I am not clear is that do we need [gs]et_task_comm?
I guess not and this patch just try to use strlcpy without task_lock.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Tao Ma <tao.ma@oracle.com>
---
kernel/workqueue.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 2994a0e..69402f8 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1730,6 +1730,7 @@ static void process_one_work(struct worker *worker, struct work_struct *work)
work_func_t f = work->func;
int work_color;
struct worker *collision;
+ char comm_saved[TASK_COMM_LEN];
#ifdef CONFIG_LOCKDEP
/*
* It is permissible to free the struct work_struct from
@@ -1790,7 +1791,16 @@ static void process_one_work(struct worker *worker, struct work_struct *work)
work_clear_pending(work);
lock_map_acquire(&cwq->wq->lockdep_map);
lock_map_acquire(&lockdep_map);
+ if (cwq->wq->name) {
+ strlcpy(comm_saved, worker->task->comm,
+ sizeof(comm_saved));
+ strlcpy(worker->task->comm, cwq->wq->name,
+ sizeof(worker->task->comm));
+ }
f(work);
+ if (cwq->wq->name)
+ strlcpy(worker->task->comm, comm_saved,
+ sizeof(worker->task->comm));
lock_map_release(&lockdep_map);
lock_map_release(&cwq->wq->lockdep_map);

--
1.7.1.GIT


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