[PATCH v2] grep: take the read-lock when adding a submodule
- From
- Martin Ågren <martin.agren@gmail.com>
- Date
- Nov 1, 2017, 20:45 UTC
- Message-ID
- <20171101204506.5481-1-martin.agren@gmail.com>
- In-Reply-To
- <CAN0heSpxJDxmSXu=P0stq+CsKVqjsvOnjDpOoMT9GdWxeZU2Pw@mail.gmail.com>
With --recurse-submodules, we add each submodule that we encounter to the list of alternate object databases. With threading, our changes to the list are not protected against races. Indeed, ThreadSanitizer reports a race when we call `add_to_alternates_memory()` around the same time that another thread is reading in the list through `read_sha1_file()`.
Take the grep read-lock while adding the submodule. The lock is used to serialize uses of non-thread-safe parts of Git's API, including `read_sha1_file()`.
Helped-by: Brandon Williams <bmwill@google.com> Signed-off-by: Martin Ågren <martin.agren@gmail.com> --- Many thanks to Brandon for showing how this should have been done.
builtin/grep.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/builtin/grep.c b/builtin/grep.c index 2d65f27d0..5a6cfe6b4 100644 --- a/builtin/grep.c +++ b/builtin/grep.c @@ -431,7 +431,9 @@ static int grep_submodule(struct grep_opt *opt, struct repository *superproject, * store is no longer global and instead is a member of the repository * object. */ + grep_read_lock(); add_to_alternates_memory(submodule.objectdir); + grep_read_unlock(); if (oid) { struct object *object;
-- 2.15.0.415.gac1375d7e