Pull release into acpica branch

1 files changed, 53 insertions, 6 deletions

diff --git a/include/linux/aio.h b/include/linux/aio.h
index a4d5af907f90..49fd37629ee4 100644
--- a/include/linux/aio.h
+++ b/include/linux/aio.h
@@ -24,7 +24,12 @@ struct kioctx;
 #define KIOCB_SYNC_KEY          (~0U)
 
 /* ki_flags bits */
-#define KIF_LOCKED              0
+/*
+ * This may be used for cancel/retry serialization in the future, but
+ * for now it's unused and we probably don't want modules to even
+ * think they can use it.
+ */
+/* #define KIF_LOCKED           0 */
 #define KIF_KICKED              1
 #define KIF_CANCELLED           2
 
@@ -43,6 +48,40 @@ struct kioctx;
 #define kiocbIsKicked(iocb)     test_bit(KIF_KICKED, &(iocb)->ki_flags)
 #define kiocbIsCancelled(iocb)  test_bit(KIF_CANCELLED, &(iocb)->ki_flags)
 
+/* is there a better place to document function pointer methods? */
+/**
+ * ki_retry     -       iocb forward progress callback
+ * @kiocb:      The kiocb struct to advance by performing an operation.
+ *
+ * This callback is called when the AIO core wants a given AIO operation
+ * to make forward progress.  The kiocb argument describes the operation
+ * that is to be performed.  As the operation proceeds, perhaps partially,
+ * ki_retry is expected to update the kiocb with progress made.  Typically
+ * ki_retry is set in the AIO core and it itself calls file_operations
+ * helpers.
+ *
+ * ki_retry's return value determines when the AIO operation is completed
+ * and an event is generated in the AIO event ring.  Except the special
+ * return values described below, the value that is returned from ki_retry
+ * is transferred directly into the completion ring as the operation's
+ * resulting status.  Once this has happened ki_retry *MUST NOT* reference
+ * the kiocb pointer again.
+ *
+ * If ki_retry returns -EIOCBQUEUED it has made a promise that aio_complete()
+ * will be called on the kiocb pointer in the future.  The AIO core will
+ * not ask the method again -- ki_retry must ensure forward progress.
+ * aio_complete() must be called once and only once in the future, multiple
+ * calls may result in undefined behaviour.
+ *
+ * If ki_retry returns -EIOCBRETRY it has made a promise that kick_iocb()
+ * will be called on the kiocb pointer in the future.  This may happen
+ * through generic helpers that associate kiocb->ki_wait with a wait
+ * queue head that ki_retry uses via current->io_wait.  It can also happen
+ * with custom tracking and manual calls to kick_iocb(), though that is
+ * discouraged.  In either case, kick_iocb() must be called once and only
+ * once.  ki_retry must ensure forward progress, the AIO core will wait
+ * indefinitely for kick_iocb() to be called.
+ */
 struct kiocb {
         struct list_head        ki_run_list;
         long                    ki_flags;
@@ -85,7 +124,7 @@ struct kiocb {
                 (x)->ki_users = 1;                      \
                 (x)->ki_key = KIOCB_SYNC_KEY;           \
                 (x)->ki_filp = (filp);                  \
-                (x)->ki_ctx = &tsk->active_mm->default_kioctx;  \
+                (x)->ki_ctx = NULL;                     \
                 (x)->ki_cancel = NULL;                  \
                 (x)->ki_dtor = NULL;                    \
                 (x)->ki_obj.tsk = tsk;                  \
@@ -144,6 +183,7 @@ struct kioctx {
         struct list_head        active_reqs;    /* used for cancellation */
         struct list_head        run_list;       /* used for kicked reqs */
 
+        /* sys_io_setup currently limits this to an unsigned int */
         unsigned                max_reqs;
 
         struct aio_ring_info    ring_info;
@@ -170,8 +210,15 @@ struct kioctx *lookup_ioctx(unsigned long ctx_id);
 int FASTCALL(io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
                                   struct iocb *iocb));
 
-#define get_ioctx(kioctx)       do { if (unlikely(atomic_read(&(kioctx)->users) <= 0)) BUG(); atomic_inc(&(kioctx)->users); } while (0)
-#define put_ioctx(kioctx)       do { if (unlikely(atomic_dec_and_test(&(kioctx)->users))) __put_ioctx(kioctx); else if (unlikely(atomic_read(&(kioctx)->users) < 0)) BUG(); } while (0)
+#define get_ioctx(kioctx) do {                                          \
+        BUG_ON(unlikely(atomic_read(&(kioctx)->users) <= 0));           \
+        atomic_inc(&(kioctx)->users);                                   \
+} while (0)
+#define put_ioctx(kioctx) do {                                          \
+        BUG_ON(unlikely(atomic_read(&(kioctx)->users) <= 0));           \
+        if (unlikely(atomic_dec_and_test(&(kioctx)->users)))            \
+                __put_ioctx(kioctx);                                    \
+} while (0)
 
 #define in_aio() !is_sync_wait(current->io_wait)
 /* may be used for debugging */
@@ -195,7 +242,7 @@ static inline struct kiocb *list_kiocb(struct list_head *h)
 }
 
 /* for sysctl: */
-extern atomic_t aio_nr;
-extern unsigned aio_max_nr;
+extern unsigned long aio_nr;
+extern unsigned long aio_max_nr;
 
 #endif /* __LINUX__AIO_H */