The driver creates its own per-CPU threads which are updated based on CPU
hotplug events. It is also possible to use kworkers and remove some of the
infrastructure get the same job done while saving a few lines of code.
bnx2fc_percpu_io_thread() becomes bnx2fc_percpu_io_work() which is
mostly the same code. The outer loop (kthread_should_stop()) gets
removed and the remaining code is shifted to the left.
In bnx2fc_process_new_cqes() the code checked for ->iothread to
decide if there is an active per-CPU thread. With the kworkers this
is no longer possible nor required. The allocation of a new work item
(via bnx2fc_alloc_work()) does no longer happen with the ->fp_work_lock
lock held. It performs only a memory allocation + initialization which
does not require any kind of serialization. The lock is held while
adding the new member to fps->work_list list.
The remaining part is the removal CPU hotplug notifier since it is taken
care by the workqueue code.
This patch was only compile-tested due to -ENODEV.
Cc: qlogic-storage-upstr...@qlogic.com
Cc: Christoph Hellwig <h...@lst.de>
Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
---
drivers/scsi/bnx2fc/bnx2fc.h | 2 +-
drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 144 ++++++--------------------------------
drivers/scsi/bnx2fc/bnx2fc_hwi.c | 22 +++---
3 files changed, 33 insertions(+), 135 deletions(-)
diff --git a/drivers/scsi/bnx2fc/bnx2fc.h b/drivers/scsi/bnx2fc/bnx2fc.h
index 4fc8ed5fe067..0279cc8de7a0 100644
--- a/drivers/scsi/bnx2fc/bnx2fc.h
+++ b/drivers/scsi/bnx2fc/bnx2fc.h
@@ -168,7 +168,7 @@ extern struct fcoe_percpu_s bnx2fc_global;
extern struct workqueue_struct *bnx2fc_wq;
struct bnx2fc_percpu_s {
- struct task_struct *iothread;
+ struct work_struct work;
struct list_head work_list;
spinlock_t fp_work_lock;
};
diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
index 93b5a0012417..329922d51f8a 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
@@ -614,39 +614,32 @@ static void bnx2fc_recv_frame(struct sk_buff *skb)
}
/**
- * bnx2fc_percpu_io_thread - thread per cpu for ios
+ * bnx2fc_percpu_io_work - work per cpu for ios
*
- * @arg: ptr to bnx2fc_percpu_info structure
+ * @work_s: The work struct
*/
-static int bnx2fc_percpu_io_thread(void *arg)
+static void bnx2fc_percpu_io_work(struct work_struct *work_s)
{
- struct bnx2fc_percpu_s *p = arg;
+ struct bnx2fc_percpu_s *p;
struct bnx2fc_work *work, *tmp;
LIST_HEAD(work_list);
- set_user_nice(current, MIN_NICE);
- set_current_state(TASK_INTERRUPTIBLE);
- while (!kthread_should_stop()) {
- schedule();
- spin_lock_bh(&p->fp_work_lock);
- while (!list_empty(&p->work_list)) {
- list_splice_init(&p->work_list, &work_list);
- spin_unlock_bh(&p->fp_work_lock);
+ p = container_of(work_s, struct bnx2fc_percpu_s, work);
- list_for_each_entry_safe(work, tmp, &work_list, list) {
- list_del_init(&work->list);
- bnx2fc_process_cq_compl(work->tgt, work->wqe);
- kfree(work);
- }
-
- spin_lock_bh(&p->fp_work_lock);
- }
- __set_current_state(TASK_INTERRUPTIBLE);
+ spin_lock_bh(&p->fp_work_lock);
+ while (!list_empty(&p->work_list)) {
+ list_splice_init(&p->work_list, &work_list);
spin_unlock_bh(&p->fp_work_lock);
- }
- __set_current_state(TASK_RUNNING);
- return 0;
+ list_for_each_entry_safe(work, tmp, &work_list, list) {
+ list_del_init(&work->list);
+ bnx2fc_process_cq_compl(work->tgt, work->wqe);
+ kfree(work);
+ }
+
+ spin_lock_bh(&p->fp_work_lock);
+ }
+ spin_unlock_bh(&p->fp_work_lock);
}
static struct fc_host_statistics *bnx2fc_get_host_stats(struct Scsi_Host
*shost)
@@ -2563,73 +2556,6 @@ static struct fcoe_transport bnx2fc_transport = {
.disable = bnx2fc_disable,
};
-/**
- * bnx2fc_percpu_thread_create - Create a receive thread for an
- * online CPU
- *
- * @cpu: cpu index for the online cpu
- */
-static void bnx2fc_percpu_thread_create(unsigned int cpu)
-{
- struct bnx2fc_percpu_s *p;
- struct task_struct *thread;
-
- p = &per_cpu(bnx2fc_percpu, cpu);
-
- thread = kthread_create_on_node(bnx2fc_percpu_io_thread,
- (void *)p, cpu_to_node(cpu),
- "bnx2fc_thread/%d", cpu);
- /* bind thread to the cpu */
- if (likely(!IS_ERR(thread))) {
- kthread_bind(thread, cpu);
- p->iothread = thread;
- wake_up_process(thread);
- }
-}
-
-static void bnx2fc_percpu_thread_destroy(unsigned int cpu)
-{
- struct bnx2fc_percpu_s *p;
- struct task_struct *thread;
- struct bnx2fc_work *work, *tmp;
-
- BNX2FC_MISC_DBG("destroying io thread for CPU %d\n", cpu);
-
- /* Prevent any new work from being queued for this CPU */
- p = &per_cpu(bnx2fc_percpu, cpu);
- spin_lock_bh(&p->fp_work_lock);
- thread = p->iothread;
- p->iothread = NULL;
-
-
- /* Free all work in the list */
- list_for_each_entry_safe(work, tmp, &p->work_list, list) {
- list_del_init(&work->list);
- bnx2fc_process_cq_compl(work->tgt, work->wqe);
- kfree(work);
- }
-
- spin_unlock_bh(&p->fp_work_lock);
-
- if (thread)
- kthread_stop(thread);
-}
-
-
-static int bnx2fc_cpu_online(unsigned int cpu)
-{
- printk(PFX "CPU %x online: Create Rx thread\n", cpu);
- bnx2fc_percpu_thread_create(cpu);
- return 0;
-}
-
-static int bnx2fc_cpu_dead(unsigned int cpu)
-{
- printk(PFX "CPU %x offline: Remove Rx thread\n", cpu);
- bnx2fc_percpu_thread_destroy(cpu);
- return 0;
-}
-
static int bnx2fc_slave_configure(struct scsi_device *sdev)
{
if (!bnx2fc_queue_depth)
@@ -2699,33 +2625,13 @@ static int __init bnx2fc_mod_init(void)
p = &per_cpu(bnx2fc_percpu, cpu);
INIT_LIST_HEAD(&p->work_list);
spin_lock_init(&p->fp_work_lock);
+ INIT_WORK(&p->work, bnx2fc_percpu_io_work);
}
- get_online_cpus();
-
- for_each_online_cpu(cpu)
- bnx2fc_percpu_thread_create(cpu);
-
- rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
- "scsi/bnx2fc:online",
- bnx2fc_cpu_online, NULL);
- if (rc < 0)
- goto stop_threads;
- bnx2fc_online_state = rc;
-
- cpuhp_setup_state_nocalls(CPUHP_SCSI_BNX2FC_DEAD, "scsi/bnx2fc:dead",
- NULL, bnx2fc_cpu_dead);
- put_online_cpus();
-
cnic_register_driver(CNIC_ULP_FCOE, &bnx2fc_cnic_cb);
return 0;
-stop_threads:
- for_each_online_cpu(cpu)
- bnx2fc_percpu_thread_destroy(cpu);
- put_online_cpus();
- kthread_stop(l2_thread);
free_wq:
destroy_workqueue(bnx2fc_wq);
release_bt:
@@ -2784,17 +2690,13 @@ static void __exit bnx2fc_mod_exit(void)
if (l2_thread)
kthread_stop(l2_thread);
- get_online_cpus();
- /* Destroy per cpu threads */
- for_each_online_cpu(cpu) {
- bnx2fc_percpu_thread_destroy(cpu);
+ for_each_possible_cpu(cpu) {
+ struct bnx2fc_percpu_s *p;
+
+ p = per_cpu_ptr(&bnx2fc_percpu, cpu);
+ flush_work(&p->work);
}
- cpuhp_remove_state_nocalls(bnx2fc_online_state);
- cpuhp_remove_state_nocalls(CPUHP_SCSI_BNX2FC_DEAD);
-
- put_online_cpus();
-
destroy_workqueue(bnx2fc_wq);
/*
* detach from scsi transport
diff --git a/drivers/scsi/bnx2fc/bnx2fc_hwi.c b/drivers/scsi/bnx2fc/bnx2fc_hwi.c
index 5ff9f89c17c7..1ed7a1784e15 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_hwi.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_hwi.c
@@ -1046,23 +1046,19 @@ int bnx2fc_process_new_cqes(struct bnx2fc_rport *tgt)
struct bnx2fc_percpu_s *fps = NULL;
unsigned int cpu = wqe % num_possible_cpus();
- fps = &per_cpu(bnx2fc_percpu, cpu);
- spin_lock_bh(&fps->fp_work_lock);
- if (unlikely(!fps->iothread))
- goto unlock;
-
work = bnx2fc_alloc_work(tgt, wqe);
- if (work)
+ if (work) {
+ fps = &per_cpu(bnx2fc_percpu, cpu);
+
+ spin_lock_bh(&fps->fp_work_lock);
list_add_tail(&work->list,
&fps->work_list);
-unlock:
- spin_unlock_bh(&fps->fp_work_lock);
-
- /* Pending work request completion */
- if (fps->iothread && work)
- wake_up_process(fps->iothread);
- else
+ spin_unlock_bh(&fps->fp_work_lock);
+ schedule_work_on(cpu, &fps->work);
+ } else {
bnx2fc_process_cq_compl(tgt, wqe);
+ }
+
num_free_sqes++;
}
cqe++;
--
2.11.0
