diff options
Diffstat (limited to 'Documentation/core-api/xarray.rst')
| -rw-r--r-- | Documentation/core-api/xarray.rst | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/Documentation/core-api/xarray.rst b/Documentation/core-api/xarray.rst index a137a0e6d068..77e0ece2b1d6 100644 --- a/Documentation/core-api/xarray.rst +++ b/Documentation/core-api/xarray.rst @@ -315,11 +315,15 @@ indeed the normal API is implemented in terms of the advanced API. The advanced API is only available to modules with a GPL-compatible license. The advanced API is based around the xa_state. This is an opaque data -structure which you declare on the stack using the XA_STATE() -macro. This macro initialises the xa_state ready to start walking -around the XArray. It is used as a cursor to maintain the position -in the XArray and let you compose various operations together without -having to restart from the top every time. +structure which you declare on the stack using the XA_STATE() macro. +This macro initialises the xa_state ready to start walking around the +XArray. It is used as a cursor to maintain the position in the XArray +and let you compose various operations together without having to restart +from the top every time. The contents of the xa_state are protected by +the rcu_read_lock() or the xas_lock(). If you need to drop whichever of +those locks is protecting your state and tree, you must call xas_pause() +so that future calls do not rely on the parts of the state which were +left unprotected. The xa_state is also used to store errors. You can call xas_error() to retrieve the error. All operations check whether |