From 6c307626f1e84fefe7da72296ce8f91b0cdd182c Mon Sep 17 00:00:00 2001 From: Matheus Tavares Date: Wed, 15 Jan 2020 23:39:57 -0300 Subject: grep: protect packed_git [re-]initialization Some fields in struct raw_object_store are lazy initialized by the thread-unsafe packfile.c:prepare_packed_git(). Although this function is present in the call stack of git-grep threads, all paths to it are currently protected by obj_read_lock() (and the main thread usually indirectly calls it before firing the worker threads, anyway). However, it's possible that future modifications add new unprotected paths to it, introducing a race condition. Because errors derived from it wouldn't happen often, it could be hard to detect. So to prevent future headaches, let's force eager initialization of packed_git when setting git-grep up. There'll be a small overhead in the cases where we didn't really need to prepare packed_git during execution but this shouldn't be very noticeable. Also, packed_git may be re-initialized by packfile.c:reprepare_packed_git(). Again, all paths to it in git-grep are already protected by obj_read_lock() but it may suffer from the same problem in the future. So let's also internally protect it with obj_read_lock() (which is a recursive mutex). Signed-off-by: Matheus Tavares Signed-off-by: Junio C Hamano --- packfile.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'packfile.c') diff --git a/packfile.c b/packfile.c index 24a73fc33a..946ca83e7a 100644 --- a/packfile.c +++ b/packfile.c @@ -1004,12 +1004,14 @@ void reprepare_packed_git(struct repository *r) { struct object_directory *odb; + obj_read_lock(); for (odb = r->objects->odb; odb; odb = odb->next) odb_clear_loose_cache(odb); r->objects->approximate_object_count_valid = 0; r->objects->packed_git_initialized = 0; prepare_packed_git(r); + obj_read_unlock(); } struct packed_git *get_packed_git(struct repository *r) -- cgit v1.3-5-g9baa