From: Sebastian Andrzej Siewior Date: Wed, 4 Oct 2017 10:24:23 +0200 Subject: [PATCH 091/353] pci/switchtec: Don't use completion's wait queue Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=fb7284f51972e4e3ba3be66b3c4ced7782166bd5 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 Cc: Logan Gunthorpe Signed-off-by: Sebastian Andrzej Siewior --- drivers/pci/switch/switchtec.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c index 291c0074ad6f..a8df847bedee 100644 --- a/drivers/pci/switch/switchtec.c +++ b/drivers/pci/switch/switchtec.c @@ -43,10 +43,11 @@ 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; @@ -68,7 +69,7 @@ static struct switchtec_user *stuser_create(struct switchtec_dev *stdev) 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); @@ -147,7 +148,7 @@ static int mrpc_queue_cmd(struct switchtec_user *stuser) 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); @@ -184,7 +185,8 @@ static void mrpc_complete_cmd(struct switchtec_dev *stdev) 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; @@ -454,10 +456,11 @@ static ssize_t switchtec_dev_read(struct file *filp, char __user *data, 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; } @@ -505,7 +508,7 @@ static __poll_t switchtec_dev_poll(struct file *filp, poll_table *wait) 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)) @@ -513,7 +516,7 @@ static __poll_t switchtec_dev_poll(struct file *filp, poll_table *wait) 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)) @@ -1037,7 +1040,8 @@ static void stdev_kill(struct switchtec_dev *stdev) /* 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); }