[SCSI] add execute_in_process_context() API

We have several points in the SCSI stack (primarily for our device
functions) where we need to guarantee process context, but (given the
place where the last reference was released) we cannot guarantee this.

This API gets around the issue by executing the function directly if
the caller has process context, but scheduling a workqueue to execute
in process context if the caller doesn't have it.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 86b111300231..957c21c16d62 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -20,6 +20,10 @@ struct work_struct {
         struct timer_list timer;
 };
 
+struct execute_work {
+        struct work_struct work;
+};
+
 #define __WORK_INITIALIZER(n, f, d) {                           \
         .entry  = { &(n).entry, &(n).entry },                   \
         .func = (f),                                            \
@@ -74,6 +78,8 @@ extern void init_workqueues(void);
 void cancel_rearming_delayed_work(struct work_struct *work);
 void cancel_rearming_delayed_workqueue(struct workqueue_struct *,
                                        struct work_struct *);
+int execute_in_process_context(void (*fn)(void *), void *,
+                               struct execute_work *);
 
 /*
  * Kill off a pending schedule_delayed_work().  Note that the work callback