| From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Date: Wed, 4 Oct 2017 10:24:23 +0200 |
| Subject: [PATCH] pci/switchtec: Don't use completion's wait queue |
| |
| The poll callback is using completion's wait_queue_head_t member and |
| puts it in poll_wait() so the poll() caller gets a wakeup after command |
| completed. This does not work on RT because we don't have a |
| wait_queue_head_t in our completion implementation. Nobody in tree does |
| like that in tree so this is the only driver that breaks. |
| |
| Instead of using the completion here is waitqueue with a status flag as |
| suggested by Logan. |
| |
| I don't have the HW so I have no idea if it works as expected, so please |
| test it. |
| |
| Cc: Kurt Schwemmer <kurt.schwemmer@microsemi.com> |
| Cc: Logan Gunthorpe <logang@deltatee.com> |
| Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| --- |
| drivers/pci/switch/switchtec.c | 22 +++++++++++++--------- |
| 1 file changed, 13 insertions(+), 9 deletions(-) |
| |
| --- a/drivers/pci/switch/switchtec.c |
| +++ b/drivers/pci/switch/switchtec.c |
| @@ -52,10 +52,11 @@ struct switchtec_user { |
| |
| enum mrpc_state state; |
| |
| - struct completion comp; |
| + wait_queue_head_t cmd_comp; |
| struct kref kref; |
| struct list_head list; |
| |
| + bool cmd_done; |
| u32 cmd; |
| u32 status; |
| u32 return_code; |
| @@ -77,7 +78,7 @@ static struct switchtec_user *stuser_cre |
| stuser->stdev = stdev; |
| kref_init(&stuser->kref); |
| INIT_LIST_HEAD(&stuser->list); |
| - init_completion(&stuser->comp); |
| + init_waitqueue_head(&stuser->cmd_comp); |
| stuser->event_cnt = atomic_read(&stdev->event_cnt); |
| |
| dev_dbg(&stdev->dev, "%s: %p\n", __func__, stuser); |
| @@ -175,7 +176,7 @@ static int mrpc_queue_cmd(struct switcht |
| kref_get(&stuser->kref); |
| stuser->read_len = sizeof(stuser->data); |
| stuser_set_state(stuser, MRPC_QUEUED); |
| - reinit_completion(&stuser->comp); |
| + stuser->cmd_done = false; |
| list_add_tail(&stuser->list, &stdev->mrpc_queue); |
| |
| mrpc_cmd_submit(stdev); |
| @@ -222,7 +223,8 @@ static void mrpc_complete_cmd(struct swi |
| memcpy_fromio(stuser->data, &stdev->mmio_mrpc->output_data, |
| stuser->read_len); |
| out: |
| - complete_all(&stuser->comp); |
| + stuser->cmd_done = true; |
| + wake_up_interruptible(&stuser->cmd_comp); |
| list_del_init(&stuser->list); |
| stuser_put(stuser); |
| stdev->mrpc_busy = 0; |
| @@ -529,10 +531,11 @@ static ssize_t switchtec_dev_read(struct |
| mutex_unlock(&stdev->mrpc_mutex); |
| |
| if (filp->f_flags & O_NONBLOCK) { |
| - if (!try_wait_for_completion(&stuser->comp)) |
| + if (!READ_ONCE(stuser->cmd_done)) |
| return -EAGAIN; |
| } else { |
| - rc = wait_for_completion_interruptible(&stuser->comp); |
| + rc = wait_event_interruptible(stuser->cmd_comp, |
| + stuser->cmd_done); |
| if (rc < 0) |
| return rc; |
| } |
| @@ -580,7 +583,7 @@ static __poll_t switchtec_dev_poll(struc |
| struct switchtec_dev *stdev = stuser->stdev; |
| __poll_t ret = 0; |
| |
| - poll_wait(filp, &stuser->comp.wait, wait); |
| + poll_wait(filp, &stuser->cmd_comp, wait); |
| poll_wait(filp, &stdev->event_wq, wait); |
| |
| if (lock_mutex_and_test_alive(stdev)) |
| @@ -588,7 +591,7 @@ static __poll_t switchtec_dev_poll(struc |
| |
| mutex_unlock(&stdev->mrpc_mutex); |
| |
| - if (try_wait_for_completion(&stuser->comp)) |
| + if (READ_ONCE(stuser->cmd_done)) |
| ret |= EPOLLIN | EPOLLRDNORM; |
| |
| if (stuser->event_cnt != atomic_read(&stdev->event_cnt)) |
| @@ -1272,7 +1275,8 @@ static void stdev_kill(struct switchtec_ |
| |
| /* Wake up and kill any users waiting on an MRPC request */ |
| list_for_each_entry_safe(stuser, tmpuser, &stdev->mrpc_queue, list) { |
| - complete_all(&stuser->comp); |
| + stuser->cmd_done = true; |
| + wake_up_interruptible(&stuser->cmd_comp); |
| list_del_init(&stuser->list); |
| stuser_put(stuser); |
| } |