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authorMatheus Tavares <matheus.bernardino@usp.br>2020-01-16 02:39:49 (GMT)
committerJunio C Hamano <gitster@pobox.com>2020-01-17 21:52:14 (GMT)
commitc3a5bb31c1567edd1671b54726d4acbb10563a2c (patch)
tree24732665ef6a84d45481b374c5e3f34f45ce135b /grep.c
parentd0654dc308b0ba76dd8ed7bbb33c8d8f7aacd783 (diff)
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grep: fix race conditions on userdiff calls
git-grep uses an internal grep_read_mutex to protect object reading operations. Similarly, there's a grep_attr_mutex to protect calls to the gitattributes machinery. However, two of the three functions protected by the last mutex may also perform object reading, as seen below: - userdiff_get_textconv() > notes_cache_init() > notes_cache_match_validity() > lookup_commit_reference_gently() > parse_object() > repo_has_object_file() > repo_has_object_file_with_flags() > oid_object_info_extended() - userdiff_find_by_path() > git_check_attr() > collect_some_attrs() > prepare_attr_stack() > read_attr() > read_attr_from_index() > read_blob_data_from_index() > read_object_file() As these calls are not protected by grep_read_mutex, there might be race conditions with other threads performing object reading (e.g. threads calling fill_textconv() at grep.c:fill_textconv_grep()). To prevent that, let's make sure to acquire the lock before both of these calls. Note: this patch might slow down the threaded grep in worktree, for the sake of thread-safeness. However, in the following patches, we should regain performance by replacing grep_read_mutex for an internal object reading lock and allowing parallel inflation during object reading. Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'grep.c')
-rw-r--r--grep.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/grep.c b/grep.c
index 0552b12..c028f70 100644
--- a/grep.c
+++ b/grep.c
@@ -1816,7 +1816,9 @@ static int grep_source_1(struct grep_opt *opt, struct grep_source *gs, int colle
* is not thread-safe.
*/
grep_attr_lock();
+ grep_read_lock();
textconv = userdiff_get_textconv(opt->repo, gs->driver);
+ grep_read_unlock();
grep_attr_unlock();
}
@@ -2184,8 +2186,11 @@ void grep_source_load_driver(struct grep_source *gs,
return;
grep_attr_lock();
- if (gs->path)
+ if (gs->path) {
+ grep_read_lock();
gs->driver = userdiff_find_by_path(istate, gs->path);
+ grep_read_unlock();
+ }
if (!gs->driver)
gs->driver = userdiff_find_by_name("default");
grep_attr_unlock();