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| author |  Matheus Tavares <matheus.bernardino@usp.br> | 2020-01-15 23:39:57 -0300 |
|---|---|---|
| committer |  Junio C Hamano <gitster@pobox.com> | 2020-01-17 13:52:14 -0800 |
| commit | 6c307626f1e84fefe7da72296ce8f91b0cdd182c (patch) | |
| tree | acbe8d44ca4634cc807bf10c5b5230bae24ac0e2 /builtin/grep.c | |
| parent | grep: allow submodule functions to run in parallel (diff) | |
| download | tgif-6c307626f1e84fefe7da72296ce8f91b0cdd182c.tar.xz | |
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 <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'builtin/grep.c')
| -rw-r--r-- | builtin/grep.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/builtin/grep.c b/builtin/grep.c index ac3d86c2e5..1535fd50f8 100644 --- a/builtin/grep.c +++ b/builtin/grep.c @@ -24,6 +24,7 @@ #include "submodule.h" #include "submodule-config.h" #include "object-store.h" +#include "packfile.h" static char const * const grep_usage[] = { N_("git grep [<options>] [-e] <pattern> [<rev>...] [[--] <path>...]"), @@ -1074,11 +1075,14 @@ int cmd_grep(int argc, const char **argv, const char *prefix) skip_first_line = 1; /* - * Pre-read gitmodules (if not read already) to prevent racy - * lazy reading in worker threads. + * Pre-read gitmodules (if not read already) and force eager + * initialization of packed_git to prevent racy lazy + * reading/initialization once worker threads are started. */ if (recurse_submodules) repo_read_gitmodules(the_repository, 1); + if (startup_info->have_repository) + (void)get_packed_git(the_repository); start_threads(&opt); } else { |