[S390] cio: wait for channel report

To fetch a pending channel report word (crw) we use a kernel
thread which triggers stcrw and sleeps on a semaphore. The s390
machine check handler uses crw_handle_channel_report to handle
one crw if needed.

This patch replaces the semaphore with a waitqueue (to block the
kernel thread) and an atomic_t (to count the number of pending
requests).

By this we achieve the ability to force this thread to check for
a pending crw (independent on when it is triggered by the machine
check handler) and wait for this action to finish.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/s390/include/asm/crw.h b/arch/s390/include/asm/crw.h
index 2185a6d619d3..749a97e61bea 100644
--- a/arch/s390/include/asm/crw.h
+++ b/arch/s390/include/asm/crw.h
@@ -32,6 +32,7 @@ typedef void (*crw_handler_t)(struct crw *, struct crw *, int);
 extern int crw_register_handler(int rsc, crw_handler_t handler);
 extern void crw_unregister_handler(int rsc);
 extern void crw_handle_channel_report(void);
+void crw_wait_for_channel_report(void);
 
 #define NR_RSCS 16