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 kthread infrastrucure.
The code checked ->thread to decide if there is an active per-CPU
thread. By using the kworker infrastructure this is no longer possible (or
required). The thread pointer is saved in `kthread' instead of `thread' so
anything trying to use thread is caught by the compiler. Currently only the
bnx2fc driver is using struct fcoe_percpu_s and the kthread member.
After a CPU went offline, we may still enqueue items on the "offline"
CPU. This isn't much of a problem. The work will be done on a random
CPU. The allocated crc_eof_page page won't be cleaned up. It is probably
expected that the CPU comes up at some point so it should not be a
problem. The crc_eof_page memory is released of course once the module is
removed.
This patch was only compile-tested due to -ENODEV.
Cc: Vasu Dev <vasu.dev@xxxxxxxxx>
Cc: "James E.J. Bottomley" <jejb@xxxxxxxxxxxxxxxxxx>
Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: fcoe-devel@xxxxxxxxxxxxx
Cc: linux-scsi@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
v1…v2: use kworker instead of smbthread as per hch
If you want this I would the same for the two bnx drivers.
drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 8 +-
drivers/scsi/fcoe/fcoe.c | 276 ++++----------------------------------
include/scsi/libfcoe.h | 6 +-
3 files changed, 34 insertions(+), 256 deletions(-)
diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
index d7029ea5d319..cfb1b5b40d6c 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
@@ -466,7 +466,7 @@ static int bnx2fc_rcv(struct sk_buff *skb, struct net_device *dev,
__skb_queue_tail(&bg->fcoe_rx_list, skb);
if (bg->fcoe_rx_list.qlen == 1)
- wake_up_process(bg->thread);
+ wake_up_process(bg->kthread);
spin_unlock(&bg->fcoe_rx_list.lock);
@@ -2663,7 +2663,7 @@ static int __init bnx2fc_mod_init(void)
}
wake_up_process(l2_thread);
spin_lock_bh(&bg->fcoe_rx_list.lock);
- bg->thread = l2_thread;
+ bg->kthread = l2_thread;
spin_unlock_bh(&bg->fcoe_rx_list.lock);
for_each_possible_cpu(cpu) {
@@ -2736,8 +2736,8 @@ static void __exit bnx2fc_mod_exit(void)
/* Destroy global thread */
bg = &bnx2fc_global;
spin_lock_bh(&bg->fcoe_rx_list.lock);
- l2_thread = bg->thread;
- bg->thread = NULL;
+ l2_thread = bg->kthread;
+ bg->kthread = NULL;
while ((skb = __skb_dequeue(&bg->fcoe_rx_list)) != NULL)
kfree_skb(skb);
diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index 0efe7112fc1f..f7c7ccc156da 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -67,9 +67,6 @@ static DEFINE_MUTEX(fcoe_config_mutex);
static struct workqueue_struct *fcoe_wq;
-/* fcoe_percpu_clean completion. Waiter protected by fcoe_create_mutex */
-static DECLARE_COMPLETION(fcoe_flush_completion);
-
/* fcoe host list */
/* must only by accessed under the RTNL mutex */
static LIST_HEAD(fcoe_hostlist);
@@ -80,7 +77,6 @@ static int fcoe_reset(struct Scsi_Host *);
static int fcoe_xmit(struct fc_lport *, struct fc_frame *);
static int fcoe_rcv(struct sk_buff *, struct net_device *,
struct packet_type *, struct net_device *);
-static int fcoe_percpu_receive_thread(void *);
static void fcoe_percpu_clean(struct fc_lport *);
static int fcoe_link_ok(struct fc_lport *);
@@ -107,7 +103,6 @@ static int fcoe_ddp_setup(struct fc_lport *, u16, struct scatterlist *,
static int fcoe_ddp_done(struct fc_lport *, u16);
static int fcoe_ddp_target(struct fc_lport *, u16, struct scatterlist *,
unsigned int);
-static int fcoe_cpu_callback(struct notifier_block *, unsigned long, void *);
static int fcoe_dcb_app_notification(struct notifier_block *notifier,
ulong event, void *ptr);
@@ -136,11 +131,6 @@ static struct notifier_block fcoe_notifier = {
.notifier_call = fcoe_device_notification,
};
-/* notification function for CPU hotplug events */
-static struct notifier_block fcoe_cpu_notifier = {
- .notifier_call = fcoe_cpu_callback,
-};
-
/* notification function for DCB events */
static struct notifier_block dcb_notifier = {
.notifier_call = fcoe_dcb_app_notification,
@@ -1245,152 +1235,21 @@ static int __exit fcoe_if_exit(void)
return 0;
}
-/**
- * fcoe_percpu_thread_create() - Create a receive thread for an online CPU
- * @cpu: The CPU index of the CPU to create a receive thread for
- */
-static void fcoe_percpu_thread_create(unsigned int cpu)
+static void fcoe_thread_cleanup_local(unsigned int cpu)
{
- struct fcoe_percpu_s *p;
- struct task_struct *thread;
-
- p = &per_cpu(fcoe_percpu, cpu);
-
- thread = kthread_create_on_node(fcoe_percpu_receive_thread,
- (void *)p, cpu_to_node(cpu),
- "fcoethread/%d", cpu);
-
- if (likely(!IS_ERR(thread))) {
- kthread_bind(thread, cpu);
- wake_up_process(thread);
-
- spin_lock_bh(&p->fcoe_rx_list.lock);
- p->thread = thread;
- spin_unlock_bh(&p->fcoe_rx_list.lock);
- }
-}
-
-/**
- * fcoe_percpu_thread_destroy() - Remove the receive thread of a CPU
- * @cpu: The CPU index of the CPU whose receive thread is to be destroyed
- *
- * Destroys a per-CPU Rx thread. Any pending skbs are moved to the
- * current CPU's Rx thread. If the thread being destroyed is bound to
- * the CPU processing this context the skbs will be freed.
- */
-static void fcoe_percpu_thread_destroy(unsigned int cpu)
-{
- struct fcoe_percpu_s *p;
- struct task_struct *thread;
struct page *crc_eof;
- struct sk_buff *skb;
-#ifdef CONFIG_SMP
- struct fcoe_percpu_s *p0;
- unsigned targ_cpu = get_cpu();
-#endif /* CONFIG_SMP */
+ struct fcoe_percpu_s *p;
- FCOE_DBG("Destroying receive thread for CPU %d\n", cpu);
-
- /* Prevent any new skbs from being queued for this CPU. */
- p = &per_cpu(fcoe_percpu, cpu);
+ p = per_cpu_ptr(&fcoe_percpu, cpu);
spin_lock_bh(&p->fcoe_rx_list.lock);
- thread = p->thread;
- p->thread = NULL;
crc_eof = p->crc_eof_page;
p->crc_eof_page = NULL;
p->crc_eof_offset = 0;
spin_unlock_bh(&p->fcoe_rx_list.lock);
-#ifdef CONFIG_SMP
- /*
- * Don't bother moving the skb's if this context is running
- * on the same CPU that is having its thread destroyed. This
- * can easily happen when the module is removed.
- */
- if (cpu != targ_cpu) {
- p0 = &per_cpu(fcoe_percpu, targ_cpu);
- spin_lock_bh(&p0->fcoe_rx_list.lock);
- if (p0->thread) {
- FCOE_DBG("Moving frames from CPU %d to CPU %d\n",
- cpu, targ_cpu);
-
- while ((skb = __skb_dequeue(&p->fcoe_rx_list)) != NULL)
- __skb_queue_tail(&p0->fcoe_rx_list, skb);
- spin_unlock_bh(&p0->fcoe_rx_list.lock);
- } else {
- /*
- * The targeted CPU is not initialized and cannot accept
- * new skbs. Unlock the targeted CPU and drop the skbs
- * on the CPU that is going offline.
- */
- while ((skb = __skb_dequeue(&p->fcoe_rx_list)) != NULL)
- kfree_skb(skb);
- spin_unlock_bh(&p0->fcoe_rx_list.lock);
- }
- } else {
- /*
- * This scenario occurs when the module is being removed
- * and all threads are being destroyed. skbs will continue
- * to be shifted from the CPU thread that is being removed
- * to the CPU thread associated with the CPU that is processing
- * the module removal. Once there is only one CPU Rx thread it
- * will reach this case and we will drop all skbs and later
- * stop the thread.
- */
- spin_lock_bh(&p->fcoe_rx_list.lock);
- while ((skb = __skb_dequeue(&p->fcoe_rx_list)) != NULL)
- kfree_skb(skb);
- spin_unlock_bh(&p->fcoe_rx_list.lock);
- }
- put_cpu();
-#else
- /*
- * This a non-SMP scenario where the singular Rx thread is
- * being removed. Free all skbs and stop the thread.
- */
- spin_lock_bh(&p->fcoe_rx_list.lock);
- while ((skb = __skb_dequeue(&p->fcoe_rx_list)) != NULL)
- kfree_skb(skb);
- spin_unlock_bh(&p->fcoe_rx_list.lock);
-#endif
-
- if (thread)
- kthread_stop(thread);
-
if (crc_eof)
put_page(crc_eof);
-}
-
-/**
- * fcoe_cpu_callback() - Handler for CPU hotplug events
- * @nfb: The callback data block
- * @action: The event triggering the callback
- * @hcpu: The index of the CPU that the event is for
- *
- * This creates or destroys per-CPU data for fcoe
- *
- * Returns NOTIFY_OK always.
- */
-static int fcoe_cpu_callback(struct notifier_block *nfb,
- unsigned long action, void *hcpu)
-{
- unsigned cpu = (unsigned long)hcpu;
-
- switch (action) {
- case CPU_ONLINE:
- case CPU_ONLINE_FROZEN:
- FCOE_DBG("CPU %x online: Create Rx thread\n", cpu);
- fcoe_percpu_thread_create(cpu);
- break;
- case CPU_DEAD:
- case CPU_DEAD_FROZEN:
- FCOE_DBG("CPU %x offline: Remove Rx thread\n", cpu);
- fcoe_percpu_thread_destroy(cpu);
- break;
- default:
- break;
- }
- return NOTIFY_OK;
+ flush_work(&p->work);
}
/**
@@ -1509,26 +1368,6 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
fps = &per_cpu(fcoe_percpu, cpu);
spin_lock(&fps->fcoe_rx_list.lock);
- if (unlikely(!fps->thread)) {
- /*
- * The targeted CPU is not ready, let's target
- * the first CPU now. For non-SMP systems this
- * will check the same CPU twice.
- */
- FCOE_NETDEV_DBG(netdev, "CPU is online, but no receive thread "
- "ready for incoming skb- using first online "
- "CPU.\n");
-
- spin_unlock(&fps->fcoe_rx_list.lock);
- cpu = cpumask_first(cpu_online_mask);
- fps = &per_cpu(fcoe_percpu, cpu);
- spin_lock(&fps->fcoe_rx_list.lock);
- if (!fps->thread) {
- spin_unlock(&fps->fcoe_rx_list.lock);
- goto err;
- }
- }
-
/*
* We now have a valid CPU that we're targeting for
* this skb. We also have this receive thread locked,
@@ -1543,8 +1382,7 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
* in softirq context.
*/
__skb_queue_tail(&fps->fcoe_rx_list, skb);
- if (fps->thread->state == TASK_INTERRUPTIBLE)
- wake_up_process(fps->thread);
+ schedule_work_on(cpu, &fps->work);
spin_unlock(&fps->fcoe_rx_list.lock);
return NET_RX_SUCCESS;
@@ -1713,15 +1551,6 @@ static int fcoe_xmit(struct fc_lport *lport, struct fc_frame *fp)
}
/**
- * fcoe_percpu_flush_done() - Indicate per-CPU queue flush completion
- * @skb: The completed skb (argument required by destructor)
- */
-static void fcoe_percpu_flush_done(struct sk_buff *skb)
-{
- complete(&fcoe_flush_completion);
-}
-
-/**
* fcoe_filter_frames() - filter out bad fcoe frames, i.e. bad CRC
* @lport: The local port the frame was received on
* @fp: The received frame
@@ -1792,8 +1621,7 @@ static void fcoe_recv_frame(struct sk_buff *skb)
fr = fcoe_dev_from_skb(skb);
lport = fr->fr_dev;
if (unlikely(!lport)) {
- if (skb->destructor != fcoe_percpu_flush_done)
- FCOE_NETDEV_DBG(skb->dev, "NULL lport in skb\n");
+ FCOE_NETDEV_DBG(skb->dev, "NULL lport in skb\n");
kfree_skb(skb);
return;
}
@@ -1857,40 +1685,28 @@ static void fcoe_recv_frame(struct sk_buff *skb)
}
/**
- * fcoe_percpu_receive_thread() - The per-CPU packet receive thread
- * @arg: The per-CPU context
+ * fcoe_receive_work() - The per-CPU worker
+ * @work: The work struct
*
- * Return: 0 for success
*/
-static int fcoe_percpu_receive_thread(void *arg)
+static void fcoe_receive_work(struct work_struct *work)
{
- struct fcoe_percpu_s *p = arg;
+ struct fcoe_percpu_s *p;
struct sk_buff *skb;
struct sk_buff_head tmp;
+ p = container_of(work, struct fcoe_percpu_s, work);
skb_queue_head_init(&tmp);
- set_user_nice(current, MIN_NICE);
+ spin_lock_bh(&p->fcoe_rx_list.lock);
+ skb_queue_splice_init(&p->fcoe_rx_list, &tmp);
+ spin_unlock_bh(&p->fcoe_rx_list.lock);
- while (!kthread_should_stop()) {
+ if (!skb_queue_len(&tmp))
+ return;
- spin_lock_bh(&p->fcoe_rx_list.lock);
- skb_queue_splice_init(&p->fcoe_rx_list, &tmp);
-
- if (!skb_queue_len(&tmp)) {
- set_current_state(TASK_INTERRUPTIBLE);
- spin_unlock_bh(&p->fcoe_rx_list.lock);
- schedule();
- continue;
- }
-
- spin_unlock_bh(&p->fcoe_rx_list.lock);
-
- while ((skb = __skb_dequeue(&tmp)) != NULL)
- fcoe_recv_frame(skb);
-
- }
- return 0;
+ while ((skb = __skb_dequeue(&tmp)))
+ fcoe_recv_frame(skb);
}
/**
@@ -2450,36 +2266,19 @@ static int fcoe_link_ok(struct fc_lport *lport)
*
* Must be called with fcoe_create_mutex held to single-thread completion.
*
- * This flushes the pending skbs by adding a new skb to each queue and
- * waiting until they are all freed. This assures us that not only are
- * there no packets that will be handled by the lport, but also that any
- * threads already handling packet have returned.
+ * This flushes the pending skbs by flush the work item for each CPU. The work
+ * item on each possible CPU is flushed because we may have used the per-CPU
+ * struct of an offline CPU.
*/
static void fcoe_percpu_clean(struct fc_lport *lport)
{
struct fcoe_percpu_s *pp;
- struct sk_buff *skb;
unsigned int cpu;
for_each_possible_cpu(cpu) {
pp = &per_cpu(fcoe_percpu, cpu);
- if (!pp->thread || !cpu_online(cpu))
- continue;
-
- skb = dev_alloc_skb(0);
- if (!skb)
- continue;
-
- skb->destructor = fcoe_percpu_flush_done;
-
- spin_lock_bh(&pp->fcoe_rx_list.lock);
- __skb_queue_tail(&pp->fcoe_rx_list, skb);
- if (pp->fcoe_rx_list.qlen == 1)
- wake_up_process(pp->thread);
- spin_unlock_bh(&pp->fcoe_rx_list.lock);
-
- wait_for_completion(&fcoe_flush_completion);
+ flush_work(&pp->work);
}
}
@@ -2625,22 +2424,11 @@ static int __init fcoe_init(void)
mutex_lock(&fcoe_config_mutex);
for_each_possible_cpu(cpu) {
- p = &per_cpu(fcoe_percpu, cpu);
+ p = per_cpu_ptr(&fcoe_percpu, cpu);
+ INIT_WORK(&p->work, fcoe_receive_work);
skb_queue_head_init(&p->fcoe_rx_list);
}
- cpu_notifier_register_begin();
-
- for_each_online_cpu(cpu)
- fcoe_percpu_thread_create(cpu);
-
- /* Initialize per CPU interrupt thread */
- rc = __register_hotcpu_notifier(&fcoe_cpu_notifier);
- if (rc)
- goto out_free;
-
- cpu_notifier_register_done();
-
/* Setup link change notification */
fcoe_dev_setup();
@@ -2652,12 +2440,6 @@ static int __init fcoe_init(void)
return 0;
out_free:
- for_each_online_cpu(cpu) {
- fcoe_percpu_thread_destroy(cpu);
- }
-
- cpu_notifier_register_done();
-
mutex_unlock(&fcoe_config_mutex);
destroy_workqueue(fcoe_wq);
return rc;
@@ -2690,14 +2472,8 @@ static void __exit fcoe_exit(void)
}
rtnl_unlock();
- cpu_notifier_register_begin();
-
- for_each_online_cpu(cpu)
- fcoe_percpu_thread_destroy(cpu);
-
- __unregister_hotcpu_notifier(&fcoe_cpu_notifier);
-
- cpu_notifier_register_done();
+ for_each_possible_cpu(cpu)
+ fcoe_thread_cleanup_local(cpu);
mutex_unlock(&fcoe_config_mutex);
diff --git a/include/scsi/libfcoe.h b/include/scsi/libfcoe.h
index de7e3ee60f0c..c6fbbb6581d3 100644
--- a/include/scsi/libfcoe.h
+++ b/include/scsi/libfcoe.h
@@ -319,14 +319,16 @@ struct fcoe_transport {
/**
* struct fcoe_percpu_s - The context for FCoE receive thread(s)
- * @thread: The thread context
+ * @kthread: The thread context (used by bnx2fc)
+ * @work: The work item (used by fcoe)
* @fcoe_rx_list: The queue of pending packets to process
* @page: The memory page for calculating frame trailer CRCs
* @crc_eof_offset: The offset into the CRC page pointing to available
* memory for a new trailer
*/
struct fcoe_percpu_s {
- struct task_struct *thread;
+ struct task_struct *kthread;
+ struct work_struct work;
struct sk_buff_head fcoe_rx_list;
struct page *crc_eof_page;
int crc_eof_offset;
--
2.8.0.rc3
--
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