[char-misc-next 17/18] mei: allow read concurrency

From: Tomas Winkler
Date: Tue Feb 10 2015 - 03:42:01 EST

Replace clunky read state machine with read stack
implemented as per client read list, this is important
mostly for mei drivers with unsolicited reads

Signed-off-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>
---
drivers/misc/mei/bus.c | 36 ++++++++++---------
drivers/misc/mei/client.c | 84 ++++++++++++++++++++++++++++----------------
drivers/misc/mei/client.h | 7 ++--
drivers/misc/mei/debugfs.c | 2 +-
drivers/misc/mei/init.c | 1 -
drivers/misc/mei/interrupt.c | 35 +++++-------------
drivers/misc/mei/main.c | 42 +++++-----------------
drivers/misc/mei/mei_dev.h | 10 +++---
8 files changed, 98 insertions(+), 119 deletions(-)

diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
index b5385372693d..17ca7e20fb6a 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -288,19 +288,20 @@ ssize_t __mei_cl_recv(struct mei_cl *cl, u8 *buf, size_t length)

mutex_lock(&dev->device_lock);

- if (!cl->read_cb) {
- rets = mei_cl_read_start(cl, length, NULL);
- if (rets < 0)
- goto out;
- }
+ cb = mei_cl_read_cb(cl, NULL);
+ if (cb)
+ goto copy;
+
+ rets = mei_cl_read_start(cl, length, NULL);
+ if (rets && rets != -EBUSY)
+ goto out;

- if (cl->reading_state != MEI_READ_COMPLETE &&
- !waitqueue_active(&cl->rx_wait)) {
+ if (list_empty(&cl->rd_completed) && !waitqueue_active(&cl->rx_wait)) {

mutex_unlock(&dev->device_lock);

if (wait_event_interruptible(cl->rx_wait,
- cl->reading_state == MEI_READ_COMPLETE ||
+ (!list_empty(&cl->rd_completed)) ||
mei_cl_is_transitioning(cl))) {

if (signal_pending(current))
@@ -309,15 +310,20 @@ ssize_t __mei_cl_recv(struct mei_cl *cl, u8 *buf, size_t length)
}

mutex_lock(&dev->device_lock);
- }

+ if (mei_cl_is_transitioning(cl)) {
+ rets = -EBUSY;
+ goto out;
+ }
+ }

- if (cl->reading_state != MEI_READ_COMPLETE) {
+ cb = mei_cl_read_cb(cl, NULL);
+ if (!cb) {
rets = 0;
goto out;
}

- cb = cl->read_cb;
+copy:
if (cb->status) {
rets = cb->status;
goto free;
@@ -329,9 +335,6 @@ ssize_t __mei_cl_recv(struct mei_cl *cl, u8 *buf, size_t length)

free:
mei_io_cb_free(cb);
- cl->read_cb = NULL;
- cl->reading_state = MEI_IDLE;
-
out:
mutex_unlock(&dev->device_lock);

@@ -443,7 +446,7 @@ int mei_cl_enable_device(struct mei_cl_device *device)

mutex_unlock(&dev->device_lock);

- if (device->event_cb && !cl->read_cb)
+ if (device->event_cb)
mei_cl_read_start(device->cl, 0, NULL);

if (!device->ops || !device->ops->enable)
@@ -485,8 +488,7 @@ int mei_cl_disable_device(struct mei_cl_device *device)
}

/* Flush queues and remove any pending read */
- mei_cl_flush_queues(cl);
- mei_io_cb_free(cl->read_cb);
+ mei_cl_flush_queues(cl, NULL);

device->event_cb = NULL;

diff --git a/drivers/misc/mei/client.c b/drivers/misc/mei/client.c
index f28eed12e7ab..e220bef0173c 100644
--- a/drivers/misc/mei/client.c
+++ b/drivers/misc/mei/client.c
@@ -458,13 +458,55 @@ struct mei_cl_cb *mei_cl_alloc_cb(struct mei_cl *cl, size_t length,
}

/**
+ * mei_cl_read_cb - find this cl's callback in the read list
+ * for a specific file
+ *
+ * @cl: host client
+ * @fp: file pointer (matching cb file object), may be NULL
+ *
+ * Return: cb on success, NULL if cb is not found
+ */
+struct mei_cl_cb *mei_cl_read_cb(const struct mei_cl *cl, const struct file *fp)
+{
+ struct mei_cl_cb *cb;
+
+ list_for_each_entry(cb, &cl->rd_completed, list)
+ if (!fp || fp == cb->file_object)
+ return cb;
+
+ return NULL;
+}
+
+/**
+ * mei_cl_read_cb_flush - free client's read pending and completed cbs
+ * for a specific file
+ *
+ * @cl: host client
+ * @fp: file pointer (matching cb file object), may be NULL
+ */
+void mei_cl_read_cb_flush(const struct mei_cl *cl, const struct file *fp)
+{
+ struct mei_cl_cb *cb, *next;
+
+ list_for_each_entry_safe(cb, next, &cl->rd_completed, list)
+ if (!fp || fp == cb->file_object)
+ mei_io_cb_free(cb);
+
+
+ list_for_each_entry_safe(cb, next, &cl->rd_pending, list)
+ if (!fp || fp == cb->file_object)
+ mei_io_cb_free(cb);
+}
+
+/**
* mei_cl_flush_queues - flushes queue lists belonging to cl.
*
* @cl: host client
+ * @fp: file pointer (matching cb file object), may be NULL
*
* Return: 0 on success, -EINVAL if cl or cl->dev is NULL.
*/
-int mei_cl_flush_queues(struct mei_cl *cl)
+int mei_cl_flush_queues(struct mei_cl *cl, const struct file *fp)
{
struct mei_device *dev;

@@ -474,13 +516,15 @@ int mei_cl_flush_queues(struct mei_cl *cl)
dev = cl->dev;

cl_dbg(dev, cl, "remove list entry belonging to cl\n");
- mei_io_list_flush(&cl->dev->read_list, cl);
mei_io_list_free(&cl->dev->write_list, cl);
mei_io_list_free(&cl->dev->write_waiting_list, cl);
mei_io_list_flush(&cl->dev->ctrl_wr_list, cl);
mei_io_list_flush(&cl->dev->ctrl_rd_list, cl);
mei_io_list_flush(&cl->dev->amthif_cmd_list, cl);
mei_io_list_flush(&cl->dev->amthif_rd_complete_list, cl);
+
+ mei_cl_read_cb_flush(cl, fp);
+
return 0;
}

@@ -497,9 +541,10 @@ void mei_cl_init(struct mei_cl *cl, struct mei_device *dev)
init_waitqueue_head(&cl->wait);
init_waitqueue_head(&cl->rx_wait);
init_waitqueue_head(&cl->tx_wait);
+ INIT_LIST_HEAD(&cl->rd_completed);
+ INIT_LIST_HEAD(&cl->rd_pending);
INIT_LIST_HEAD(&cl->link);
INIT_LIST_HEAD(&cl->device_link);
- cl->reading_state = MEI_IDLE;
cl->writing_state = MEI_IDLE;
cl->dev = dev;
}
@@ -524,24 +569,6 @@ struct mei_cl *mei_cl_allocate(struct mei_device *dev)
}

/**
- * mei_cl_find_read_cb - find this cl's callback in the read list
- *
- * @cl: host client
- *
- * Return: cb on success, NULL on error
- */
-struct mei_cl_cb *mei_cl_find_read_cb(struct mei_cl *cl)
-{
- struct mei_device *dev = cl->dev;
- struct mei_cl_cb *cb;
-
- list_for_each_entry(cb, &dev->read_list.list, list)
- if (mei_cl_cmp_id(cl, cb->cl))
- return cb;
- return NULL;
-}
-
-/**
* mei_cl_link - allocate host id in the host map
*
* @cl: host client
@@ -1006,10 +1033,10 @@ int mei_cl_read_start(struct mei_cl *cl, size_t length, struct file *fp)
if (!mei_cl_is_connected(cl))
return -ENODEV;

- if (cl->read_cb) {
- cl_dbg(dev, cl, "read is pending.\n");
+ /* HW currently supports only one pending read */
+ if (!list_empty(&cl->rd_pending))
return -EBUSY;
- }
+
me_cl = mei_me_cl_by_uuid_id(dev, &cl->cl_uuid, cl->me_client_id);
if (!me_cl) {
cl_err(dev, cl, "no such me client %d\n", cl->me_client_id);
@@ -1036,13 +1063,11 @@ int mei_cl_read_start(struct mei_cl *cl, size_t length, struct file *fp)
if (rets < 0)
goto out;

- list_add_tail(&cb->list, &dev->read_list.list);
+ list_add_tail(&cb->list, &cl->rd_pending);
} else {
list_add_tail(&cb->list, &dev->ctrl_wr_list.list);
}

- cl->read_cb = cb;
-
out:
cl_dbg(dev, cl, "rpm: autosuspend\n");
pm_runtime_mark_last_busy(dev->dev);
@@ -1267,9 +1292,8 @@ void mei_cl_complete(struct mei_cl *cl, struct mei_cl_cb *cb)
if (waitqueue_active(&cl->tx_wait))
wake_up_interruptible(&cl->tx_wait);

- } else if (cb->fop_type == MEI_FOP_READ &&
- MEI_READING == cl->reading_state) {
- cl->reading_state = MEI_READ_COMPLETE;
+ } else if (cb->fop_type == MEI_FOP_READ) {
+ list_add_tail(&cb->list, &cl->rd_completed);
if (waitqueue_active(&cl->rx_wait))
wake_up_interruptible(&cl->rx_wait);
else
diff --git a/drivers/misc/mei/client.h b/drivers/misc/mei/client.h
index c3d0e200a642..eb02f34b2fe0 100644
--- a/drivers/misc/mei/client.h
+++ b/drivers/misc/mei/client.h
@@ -77,11 +77,12 @@ int mei_cl_unlink(struct mei_cl *cl);

struct mei_cl *mei_cl_alloc_linked(struct mei_device *dev, int id);

-int mei_cl_flush_queues(struct mei_cl *cl);
-struct mei_cl_cb *mei_cl_find_read_cb(struct mei_cl *cl);
-
+struct mei_cl_cb *mei_cl_read_cb(const struct mei_cl *cl,
+ const struct file *fp);
+void mei_cl_read_cb_flush(const struct mei_cl *cl, const struct file *fp);
struct mei_cl_cb *mei_cl_alloc_cb(struct mei_cl *cl, size_t length,
enum mei_cb_file_ops type, struct file *fp);
+int mei_cl_flush_queues(struct mei_cl *cl, const struct file *fp);

int mei_cl_flow_ctrl_creds(struct mei_cl *cl);

diff --git a/drivers/misc/mei/debugfs.c b/drivers/misc/mei/debugfs.c
index 50fc6635fab1..d9cd7e6ee484 100644
--- a/drivers/misc/mei/debugfs.c
+++ b/drivers/misc/mei/debugfs.c
@@ -117,7 +117,7 @@ static ssize_t mei_dbgfs_read_active(struct file *fp, char __user *ubuf,
pos += scnprintf(buf + pos, bufsz - pos,
"%2d|%2d|%4d|%5d|%2d|%2d|\n",
i, cl->me_client_id, cl->host_client_id, cl->state,
- cl->reading_state, cl->writing_state);
+ !list_empty(&cl->rd_completed), cl->writing_state);
i++;
}
out:
diff --git a/drivers/misc/mei/init.c b/drivers/misc/mei/init.c
index ad18b0d16f61..97353cf8d9b6 100644
--- a/drivers/misc/mei/init.c
+++ b/drivers/misc/mei/init.c
@@ -397,7 +397,6 @@ void mei_device_init(struct mei_device *dev,
dev->dev_state = MEI_DEV_INITIALIZING;
dev->reset_count = 0;

- mei_io_list_init(&dev->read_list);
mei_io_list_init(&dev->write_list);
mei_io_list_init(&dev->write_waiting_list);
mei_io_list_init(&dev->ctrl_wr_list);
diff --git a/drivers/misc/mei/interrupt.c b/drivers/misc/mei/interrupt.c
index 1e2f3c774853..3f23629759db 100644
--- a/drivers/misc/mei/interrupt.c
+++ b/drivers/misc/mei/interrupt.c
@@ -68,18 +68,6 @@ static inline int mei_cl_hbm_equal(struct mei_cl *cl,
return cl->host_client_id == mei_hdr->host_addr &&
cl->me_client_id == mei_hdr->me_addr;
}
-/**
- * mei_cl_is_reading - checks if the client is in reading state
- *
- * @cl: mei client
- *
- * Return: true if the client is reading
- */
-static bool mei_cl_is_reading(struct mei_cl *cl)
-{
- return cl->state == MEI_FILE_CONNECTED &&
- cl->reading_state != MEI_READ_COMPLETE;
-}

/**
* mei_irq_discard_msg - discard received message
@@ -116,24 +104,18 @@ int mei_cl_irq_read_msg(struct mei_cl *cl,
struct mei_cl_cb *cb;
unsigned char *buffer = NULL;

- list_for_each_entry(cb, &dev->read_list.list, list) {
- if (cl == cb->cl)
- break;
- }
-
- if (&cb->list == &dev->read_list.list) {
- dev_err(dev->dev, "no reader found\n");
+ cb = list_first_entry_or_null(&cl->rd_pending, struct mei_cl_cb, list);
+ if (!cb) {
+ cl_err(dev, cl, "pending read cb not found\n");
goto out;
}

- if (!mei_cl_is_reading(cl)) {
- cl_err(dev, cl, "cl is not reading state=%d reading state=%d\n",
- cl->state, cl->reading_state);
+ if (cl->state != MEI_FILE_CONNECTED) {
+ cl_dbg(dev, cl, "not connected\n");
+ cb->status = -ENODEV;
goto out;
}

- cl->reading_state = MEI_READING;
-
if (cb->buf.size == 0 || cb->buf.data == NULL) {
cl_err(dev, cl, "response buffer is not allocated.\n");
list_move_tail(&cb->list, &complete_list->list);
@@ -163,8 +145,7 @@ int mei_cl_irq_read_msg(struct mei_cl *cl,

if (mei_hdr->msg_complete) {
cb->read_time = jiffies;
- cl_dbg(dev, cl, "completed read length = %lu\n",
- cb->buf_idx);
+ cl_dbg(dev, cl, "completed read length = %lu\n", cb->buf_idx);
list_move_tail(&cb->list, &complete_list->list);
}

@@ -281,7 +262,7 @@ static int mei_cl_irq_read(struct mei_cl *cl, struct mei_cl_cb *cb,
return ret;
}

- list_move_tail(&cb->list, &dev->read_list.list);
+ list_move_tail(&cb->list, &cl->rd_pending);

return 0;
}
diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index c34853be963f..d80867e0d803 100644
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -112,14 +112,11 @@ static int mei_release(struct inode *inode, struct file *file)
cl_dbg(dev, cl, "disconnecting\n");
rets = mei_cl_disconnect(cl);
}
- mei_cl_flush_queues(cl);
+ mei_cl_flush_queues(cl, file);
cl_dbg(dev, cl, "removing\n");

mei_cl_unlink(cl);

- mei_io_cb_free(cl->read_cb);
- cl->read_cb = NULL;
-
file->private_data = NULL;

kfree(cl);
@@ -143,8 +140,8 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
size_t length, loff_t *offset)
{
struct mei_cl *cl = file->private_data;
- struct mei_cl_cb *cb = NULL;
struct mei_device *dev;
+ struct mei_cl_cb *cb = NULL;
int rets;
int err;

@@ -171,7 +168,7 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
goto out;
}

- cb = cl->read_cb;
+ cb = mei_cl_read_cb(cl, file);
if (cb) {
/* read what left */
if (cb->buf_idx > *offset)
@@ -196,9 +193,7 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
goto out;
}

- if (MEI_READ_COMPLETE != cl->reading_state &&
- !waitqueue_active(&cl->rx_wait)) {
-
+ if (list_empty(&cl->rd_completed) && !waitqueue_active(&cl->rx_wait)) {
if (file->f_flags & O_NONBLOCK) {
rets = -EAGAIN;
goto out;
@@ -207,7 +202,7 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
mutex_unlock(&dev->device_lock);

if (wait_event_interruptible(cl->rx_wait,
- MEI_READ_COMPLETE == cl->reading_state ||
+ (!list_empty(&cl->rd_completed)) ||
mei_cl_is_transitioning(cl))) {

if (signal_pending(current))
@@ -222,14 +217,8 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
}
}

- cb = cl->read_cb;
-
+ cb = mei_cl_read_cb(cl, file);
if (!cb) {
- rets = -ENODEV;
- goto out;
- }
-
- if (cl->reading_state != MEI_READ_COMPLETE) {
rets = 0;
goto out;
}
@@ -266,9 +255,7 @@ copy_buffer:

free:
mei_io_cb_free(cb);
- cl->read_cb = NULL;

- cl->reading_state = MEI_IDLE;
out:
dev_dbg(dev->dev, "end mei read rets= %d\n", rets);
mutex_unlock(&dev->device_lock);
@@ -335,8 +322,7 @@ static ssize_t mei_write(struct file *file, const char __user *ubuf,
timeout = write_cb->read_time +
mei_secs_to_jiffies(MEI_IAMTHIF_READ_TIMER);

- if (time_after(jiffies, timeout) ||
- cl->reading_state == MEI_READ_COMPLETE) {
+ if (time_after(jiffies, timeout)) {
*offset = 0;
mei_io_cb_free(write_cb);
write_cb = NULL;
@@ -344,19 +330,7 @@ static ssize_t mei_write(struct file *file, const char __user *ubuf,
}
}

- /* free entry used in read */
- if (cl->reading_state == MEI_READ_COMPLETE) {
- *offset = 0;
- write_cb = mei_cl_find_read_cb(cl);
- if (write_cb) {
- mei_io_cb_free(write_cb);
- write_cb = NULL;
- cl->read_cb = NULL;
- cl->reading_state = MEI_IDLE;
- }
- } else if (cl->reading_state == MEI_IDLE)
- *offset = 0;
-
+ *offset = 0;
write_cb = mei_cl_alloc_cb(cl, length, MEI_FOP_WRITE, file);
if (!write_cb) {
rets = -ENOMEM;
diff --git a/drivers/misc/mei/mei_dev.h b/drivers/misc/mei/mei_dev.h
index 1a0f6e9588b6..f066ecd71939 100644
--- a/drivers/misc/mei/mei_dev.h
+++ b/drivers/misc/mei/mei_dev.h
@@ -231,9 +231,9 @@ struct mei_cl_cb {
* @me_client_id: me/fw id
* @mei_flow_ctrl_creds: transmit flow credentials
* @timer_count: watchdog timer for operation completion
- * @reading_state: state of the rx
* @writing_state: state of the tx
- * @read_cb: current pending reading callback
+ * @rd_pending: pending read credits
+ * @rd_completed: completed read
*
* @device: device on the mei client bus
* @device_link: link to bus clients
@@ -251,9 +251,9 @@ struct mei_cl {
u8 me_client_id;
u8 mei_flow_ctrl_creds;
u8 timer_count;
- enum mei_file_transaction_states reading_state;
enum mei_file_transaction_states writing_state;
- struct mei_cl_cb *read_cb;
+ struct list_head rd_pending;
+ struct list_head rd_completed;

/* MEI CL bus data */
struct mei_cl_device *device;
@@ -425,7 +425,6 @@ const char *mei_pg_state_str(enum mei_pg_state state);
* @cdev : character device
* @minor : minor number allocated for device
*
- * @read_list : read completion list
* @write_list : write pending list
* @write_waiting_list : write completion list
* @ctrl_wr_list : pending control write list
@@ -501,7 +500,6 @@ struct mei_device {
struct cdev cdev;
int minor;

- struct mei_cl_cb read_list;
struct mei_cl_cb write_list;
struct mei_cl_cb write_waiting_list;
struct mei_cl_cb ctrl_wr_list;
--
1.9.3

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