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grep: Fix race condition in delta_base_cache

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When running large git grep (ie: git grep regexp $(git rev-list --all)), glibc error sometimes occur:
*** glibc detected *** git: double free or corruption (!prev): 0x00000000010abdf0 ***

According to gdb the problem originate from release_delta_cash (sha1_file.c:1703)
		free(ent->data);

>From my analysis it seems that git grep threads do acquire lock before calling read_sha1_file but not before calling
read_object_with_reference who ends up calling read_sha1_file too.

Adding the lock around read_object_with_reference seems to fix the issue for me.
I've ran git grep about a dozen time and seen no more error while
it usually happened half the time before.

Signed-off-by: Nicolas Morey-Chaisemartin <nicolas@morey-chaisemartin.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Nicolas Morey-Chaisemartin 2011-08-30 15:45:38 +02:00 committed by Junio C Hamano
parent 5b594f457a
commit 8cb5775b2b
1 changed files with 4 additions and 0 deletions
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4
builtin-grep.c
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@ -632,8 +632,12 @@ static int grep_object(struct grep_opt *opt, const char **paths,
void *data; void *data;
unsigned long size; unsigned long size;
int hit; int hit;
read_sha1_lock();
data = read_object_with_reference(obj->sha1, tree_type, data = read_object_with_reference(obj->sha1, tree_type,
&size, NULL); &size, NULL);
read_sha1_unlock();
if (!data) if (!data)
die("unable to read tree (%s)", sha1_to_hex(obj->sha1)); die("unable to read tree (%s)", sha1_to_hex(obj->sha1));
init_tree_desc(&tree, data, size); init_tree_desc(&tree, data, size);