Commit deaa0a8a authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Peter Zijlstra

pci/switchtec: Replace completion wait queue usage for poll

The poll callback is using the completion wait queue and sticks it into
poll_wait() to wake up pollers after a command has completed.

This works to some extent, but cannot provide EPOLLEXCLUSIVE support
because the waker side uses complete_all() which unconditionally wakes up
all waiters. complete_all() is required because completions internally use
exclusive wait and complete() only wakes up one waiter by default.

This mixes conceptually different mechanisms and relies on internal
implementation details of completions, which in turn puts contraints on
changing the internal implementation of completions.

Replace it with a regular wait queue and store the state in struct
switchtec_user.
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarLogan Gunthorpe <logang@deltatee.com>
Acked-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113240.936097534@linutronix.de
parent efbdc769
...@@ -52,10 +52,11 @@ struct switchtec_user { ...@@ -52,10 +52,11 @@ struct switchtec_user {
enum mrpc_state state; enum mrpc_state state;
struct completion comp; wait_queue_head_t cmd_comp;
struct kref kref; struct kref kref;
struct list_head list; struct list_head list;
bool cmd_done;
u32 cmd; u32 cmd;
u32 status; u32 status;
u32 return_code; u32 return_code;
...@@ -77,7 +78,7 @@ static struct switchtec_user *stuser_create(struct switchtec_dev *stdev) ...@@ -77,7 +78,7 @@ static struct switchtec_user *stuser_create(struct switchtec_dev *stdev)
stuser->stdev = stdev; stuser->stdev = stdev;
kref_init(&stuser->kref); kref_init(&stuser->kref);
INIT_LIST_HEAD(&stuser->list); INIT_LIST_HEAD(&stuser->list);
init_completion(&stuser->comp); init_waitqueue_head(&stuser->cmd_comp);
stuser->event_cnt = atomic_read(&stdev->event_cnt); stuser->event_cnt = atomic_read(&stdev->event_cnt);
dev_dbg(&stdev->dev, "%s: %p\n", __func__, stuser); dev_dbg(&stdev->dev, "%s: %p\n", __func__, stuser);
...@@ -175,7 +176,7 @@ static int mrpc_queue_cmd(struct switchtec_user *stuser) ...@@ -175,7 +176,7 @@ static int mrpc_queue_cmd(struct switchtec_user *stuser)
kref_get(&stuser->kref); kref_get(&stuser->kref);
stuser->read_len = sizeof(stuser->data); stuser->read_len = sizeof(stuser->data);
stuser_set_state(stuser, MRPC_QUEUED); stuser_set_state(stuser, MRPC_QUEUED);
reinit_completion(&stuser->comp); stuser->cmd_done = false;
list_add_tail(&stuser->list, &stdev->mrpc_queue); list_add_tail(&stuser->list, &stdev->mrpc_queue);
mrpc_cmd_submit(stdev); mrpc_cmd_submit(stdev);
...@@ -222,7 +223,8 @@ static void mrpc_complete_cmd(struct switchtec_dev *stdev) ...@@ -222,7 +223,8 @@ static void mrpc_complete_cmd(struct switchtec_dev *stdev)
memcpy_fromio(stuser->data, &stdev->mmio_mrpc->output_data, memcpy_fromio(stuser->data, &stdev->mmio_mrpc->output_data,
stuser->read_len); stuser->read_len);
out: out:
complete_all(&stuser->comp); stuser->cmd_done = true;
wake_up_interruptible(&stuser->cmd_comp);
list_del_init(&stuser->list); list_del_init(&stuser->list);
stuser_put(stuser); stuser_put(stuser);
stdev->mrpc_busy = 0; stdev->mrpc_busy = 0;
...@@ -529,10 +531,11 @@ static ssize_t switchtec_dev_read(struct file *filp, char __user *data, ...@@ -529,10 +531,11 @@ static ssize_t switchtec_dev_read(struct file *filp, char __user *data,
mutex_unlock(&stdev->mrpc_mutex); mutex_unlock(&stdev->mrpc_mutex);
if (filp->f_flags & O_NONBLOCK) { if (filp->f_flags & O_NONBLOCK) {
if (!try_wait_for_completion(&stuser->comp)) if (!stuser->cmd_done)
return -EAGAIN; return -EAGAIN;
} else { } else {
rc = wait_for_completion_interruptible(&stuser->comp); rc = wait_event_interruptible(stuser->cmd_comp,
stuser->cmd_done);
if (rc < 0) if (rc < 0)
return rc; return rc;
} }
...@@ -580,7 +583,7 @@ static __poll_t switchtec_dev_poll(struct file *filp, poll_table *wait) ...@@ -580,7 +583,7 @@ static __poll_t switchtec_dev_poll(struct file *filp, poll_table *wait)
struct switchtec_dev *stdev = stuser->stdev; struct switchtec_dev *stdev = stuser->stdev;
__poll_t ret = 0; __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); poll_wait(filp, &stdev->event_wq, wait);
if (lock_mutex_and_test_alive(stdev)) if (lock_mutex_and_test_alive(stdev))
...@@ -588,7 +591,7 @@ static __poll_t switchtec_dev_poll(struct file *filp, poll_table *wait) ...@@ -588,7 +591,7 @@ static __poll_t switchtec_dev_poll(struct file *filp, poll_table *wait)
mutex_unlock(&stdev->mrpc_mutex); mutex_unlock(&stdev->mrpc_mutex);
if (try_wait_for_completion(&stuser->comp)) if (stuser->cmd_done)
ret |= EPOLLIN | EPOLLRDNORM; ret |= EPOLLIN | EPOLLRDNORM;
if (stuser->event_cnt != atomic_read(&stdev->event_cnt)) if (stuser->event_cnt != atomic_read(&stdev->event_cnt))
...@@ -1272,7 +1275,8 @@ static void stdev_kill(struct switchtec_dev *stdev) ...@@ -1272,7 +1275,8 @@ static void stdev_kill(struct switchtec_dev *stdev)
/* Wake up and kill any users waiting on an MRPC request */ /* Wake up and kill any users waiting on an MRPC request */
list_for_each_entry_safe(stuser, tmpuser, &stdev->mrpc_queue, list) { 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); list_del_init(&stuser->list);
stuser_put(stuser); stuser_put(stuser);
} }
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment