[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>

3 files changed, 40 insertions, 14 deletions

diff --git a/drivers/misc/ibmasm/event.c b/drivers/misc/ibmasm/event.c
index e100f34f1587..fe1e819235a4 100644
--- a/drivers/misc/ibmasm/event.c
+++ b/drivers/misc/ibmasm/event.c
@@ -23,6 +23,7 @@
  */
 
 #include "ibmasm.h"
+#include "lowlevel.h"
 
 /*
  * ASM service processor event handling routines.
@@ -34,7 +35,6 @@
  * circular buffer.
  */
 
-
 static void wake_up_event_readers(struct service_processor *sp)
 {
         struct event_reader *reader;
@@ -63,7 +63,7 @@ void ibmasm_receive_event(struct service_processor *sp, void *data, unsigned int
         spin_lock_irqsave(&sp->lock, flags);
         /* copy the event into the next slot in the circular buffer */
         event = &buffer->events[buffer->next_index];
-        memcpy(event->data, data, data_size);
+        memcpy_fromio(event->data, data, data_size);
         event->data_size = data_size;
         event->serial_number = buffer->next_serial_number;
 
@@ -93,7 +93,10 @@ int ibmasm_get_next_event(struct service_processor *sp, struct event_reader *rea
         unsigned int index;
         unsigned long flags;
 
-        if (wait_event_interruptible(reader->wait, event_available(buffer, reader)))
+        reader->cancelled = 0;
+
+        if (wait_event_interruptible(reader->wait,
+                        event_available(buffer, reader) || reader->cancelled))
                 return -ERESTARTSYS;
 
         if (!event_available(buffer, reader))
@@ -116,6 +119,12 @@ int ibmasm_get_next_event(struct service_processor *sp, struct event_reader *rea
         return event->data_size;
 }
 
+void ibmasm_cancel_next_event(struct event_reader *reader)
+{
+        reader->cancelled = 1;
+        wake_up_interruptible(&reader->wait);
+}
+
 void ibmasm_event_reader_register(struct service_processor *sp, struct event_reader *reader)
 {
         unsigned long flags;
@@ -131,8 +140,6 @@ void ibmasm_event_reader_unregister(struct service_processor *sp, struct event_r
 {
         unsigned long flags;
 
-        wake_up_interruptible(&reader->wait);
-
         spin_lock_irqsave(&sp->lock, flags);
         list_del(&reader->node);
         spin_unlock_irqrestore(&sp->lock, flags);
@@ -164,6 +171,5 @@ int ibmasm_event_buffer_init(struct service_processor *sp)
 
 void ibmasm_event_buffer_exit(struct service_processor *sp)
 {
-        wake_up_event_readers(sp);
         kfree(sp->event_buffer);
 }
diff --git a/drivers/misc/ibmasm/ibmasm.h b/drivers/misc/ibmasm/ibmasm.h
index 1e83406382e7..35c4def5af18 100644
--- a/drivers/misc/ibmasm/ibmasm.h
+++ b/drivers/misc/ibmasm/ibmasm.h
@@ -108,6 +108,7 @@ struct event_buffer {
 };
 
 struct event_reader {
+        int                     cancelled;
         unsigned int            next_serial_number;
         wait_queue_head_t       wait;
         struct list_head        node;
@@ -185,6 +186,7 @@ extern void ibmasm_receive_event(struct service_processor *sp, void *data,  unsi
 extern void ibmasm_event_reader_register(struct service_processor *sp, struct event_reader *reader);
 extern void ibmasm_event_reader_unregister(struct service_processor *sp, struct event_reader *reader);
 extern int ibmasm_get_next_event(struct service_processor *sp, struct event_reader *reader);
+extern void ibmasm_cancel_next_event(struct event_reader *reader);
 
 /* heartbeat - from SP to OS */
 extern void ibmasm_register_panic_notifier(void);
diff --git a/drivers/misc/ibmasm/ibmasmfs.c b/drivers/misc/ibmasm/ibmasmfs.c
index 866e867e68f2..c87ef7d82b70 100644
--- 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;
 }