[PATCH] ibmasm driver: correctly wake up sleeping threads
Due to my incomplete understanding of the wait_event_interruptible() function
threads waiting for service processor events were not woken up. This patch
fixes that problem.
Signed-off-by: Max Asbock <masbock@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/misc/ibmasm/ibmasmfs.c b/drivers/misc/ibmasm/ibmasmfs.c
index 866e867..c87ef7d 100644
--- a/drivers/misc/ibmasm/ibmasmfs.c
+++ b/drivers/misc/ibmasm/ibmasmfs.c
@@ -374,6 +374,7 @@
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 @@
{
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 @@
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 @@
if (*offset != 0)
return 0;
- wake_up_interruptible(&event_data->reader.wait);
+ ibmasm_cancel_next_event(&event_data->reader);
return 0;
}