[PATCH] ibmasm driver: correctly wake up sleeping threads

[firefly-linux-kernel-4.4.55.git] / drivers / misc / ibmasm / ibmasmfs.c

diff --git a/drivers/misc/ibmasm/ibmasmfs.c b/drivers/misc/ibmasm/ibmasmfs.c
index 866e867e68f2ac95f853747f443471c9f4c425f4..c87ef7d82b70be09b72bb724fe6d8c217aaae771 100644 (file)
--- a/drivers/misc/ibmasm/ibmasmfs.c
+++ b/drivers/misc/ibmasm/ibmasmfs.c
@@ -374,6 +374,7 @@ static int event_file_open(struct inode *inode, struct file *file)
        ibmasm_event_reader_register(sp, &event_data->reader);
 
        event_data->sp = sp;
+       event_data->active = 0;
        file->private_data = event_data;
        return 0;
 }
@@ -391,7 +392,9 @@ static ssize_t event_file_read(struct file *file, char __user *buf, size_t count
 {
        struct ibmasmfs_event_data *event_data = file->private_data;
        struct event_reader *reader = &event_data->reader;
+       struct service_processor *sp = event_data->sp;
        int ret;
+       unsigned long flags;
 
        if (*offset < 0)
                return -EINVAL;
@@ -400,17 +403,32 @@ static ssize_t event_file_read(struct file *file, char __user *buf, size_t count
        if (*offset != 0)
                return 0;
 
-       ret = ibmasm_get_next_event(event_data->sp, reader);
+       spin_lock_irqsave(&sp->lock, flags);
+       if (event_data->active) {
+               spin_unlock_irqrestore(&sp->lock, flags);
+               return -EBUSY;
+       }
+       event_data->active = 1;
+       spin_unlock_irqrestore(&sp->lock, flags);
+
+       ret = ibmasm_get_next_event(sp, reader);
        if (ret <= 0)
-               return ret;
+               goto out;
 
-       if (count < reader->data_size)
-               return -EINVAL;
+       if (count < reader->data_size) {
+               ret = -EINVAL;
+               goto out;
+       }
 
-        if (copy_to_user(buf, reader->data, reader->data_size))
-               return -EFAULT;
+        if (copy_to_user(buf, reader->data, reader->data_size)) {
+               ret = -EFAULT;
+               goto out;
+       }
+       ret = reader->data_size;
 
-       return reader->data_size;
+out:
+       event_data->active = 0;
+       return ret;
 }
 
 static ssize_t event_file_write(struct file *file, const char __user *buf, size_t count, loff_t *offset)
@@ -424,7 +442,7 @@ static ssize_t event_file_write(struct file *file, const char __user *buf, size_
        if (*offset != 0)
                return 0;
 
-       wake_up_interruptible(&event_data->reader.wait);
+       ibmasm_cancel_next_event(&event_data->reader);
        return 0;
 }