From: Richard W.M. Jones Date: Tue, 26 Jul 2011 17:57:19 +0000 (+0100) Subject: ocaml: Fix locking in event callbacks. X-Git-Tag: 1.10.6~2 X-Git-Url: http://git.annexia.org/?a=commitdiff_plain;h=019904721b01adf2def2added7ca6b52c55563a8;p=libguestfs.git ocaml: Fix locking in event callbacks. We weren't acquiring the GC lock around some allocations, resulting in segfaults when an event callback ran at the same time as a main thread allocation or garbage collection. In particular this fixes a noticable crash in guestfs-browser. (Cherry picked from commit 2b8b3f9794ceb43eabd3083e225c669896d8b186). --- diff --git a/ocaml/guestfs_c.c b/ocaml/guestfs_c.c index a1386ec..2270289 100644 --- a/ocaml/guestfs_c.c +++ b/ocaml/guestfs_c.c @@ -325,13 +325,13 @@ event_bitmask_to_event (uint64_t event) } static void -event_callback_wrapper (guestfs_h *g, - void *data, - uint64_t event, - int event_handle, - int flags, - const char *buf, size_t buf_len, - const uint64_t *array, size_t array_len) +event_callback_wrapper_locked (guestfs_h *g, + void *data, + uint64_t event, + int event_handle, + int flags, + const char *buf, size_t buf_len, + const uint64_t *array, size_t array_len) { CAMLparam0 (); CAMLlocal5 (gv, evv, ehv, bufv, arrayv); @@ -358,9 +358,7 @@ event_callback_wrapper (guestfs_h *g, value args[5] = { gv, evv, ehv, bufv, arrayv }; - caml_leave_blocking_section (); rv = caml_callbackN_exn (*(value*)data, 5, args); - caml_enter_blocking_section (); /* Callbacks shouldn't throw exceptions. There's not much we can do * except to print it. @@ -372,3 +370,23 @@ event_callback_wrapper (guestfs_h *g, CAMLreturn0; } + +static void +event_callback_wrapper (guestfs_h *g, + void *data, + uint64_t event, + int event_handle, + int flags, + const char *buf, size_t buf_len, + const uint64_t *array, size_t array_len) +{ + /* Ensure we are holding the GC lock before any GC operations are + * possible. (RHBZ#725824) + */ + caml_leave_blocking_section (); + + event_callback_wrapper_locked (g, data, event, event_handle, flags, + buf, buf_len, array, array_len); + + caml_enter_blocking_section (); +}