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[PATCH v3 06/12] do_for_each_entry(): increment the packed refs cache refcount

From
Michael Haggerty <mhagger@alum.mit.edu>
Date
Jun 20, 2013, 08:37 UTC
Message-ID
<1371717474-28942-7-git-send-email-mhagger@alum.mit.edu>
In-Reply-To
<1371717474-28942-1-git-send-email-mhagger@alum.mit.edu>

This function calls a user-supplied callback function which could do something that causes the packed refs cache to be invalidated. So acquire a reference count on the data structure to prevent our copy from being freed while we are iterating over it.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---
 refs.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/refs.c b/refs.c
index 80c172f..f33d224 100644
--- a/refs.c
+++ b/refs.c
@@ -1590,10 +1590,12 @@ void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 static int do_for_each_entry(struct ref_cache *refs, const char *base,
 			     each_ref_entry_fn fn, void *cb_data)
 {
-	struct ref_dir *packed_dir = get_packed_refs(refs);
+	struct packed_ref_cache *packed_ref_cache = get_packed_ref_cache(refs);
+	struct ref_dir *packed_dir = get_packed_ref_dir(packed_ref_cache);
 	struct ref_dir *loose_dir = get_loose_refs(refs);
 	int retval = 0;
 
+	acquire_packed_ref_cache(packed_ref_cache);
 	if (base && *base) {
 		packed_dir = find_containing_dir(packed_dir, base, 0);
 		loose_dir = find_containing_dir(loose_dir, base, 0);
@@ -1614,6 +1616,7 @@ static int do_for_each_entry(struct ref_cache *refs, const char *base,
 				loose_dir, 0, fn, cb_data);
 	}
 
+	release_packed_ref_cache(packed_ref_cache);
 	return retval;
 }
 

-- 
1.8.3.1
Previous: Michael HaggertyNext: Michael Haggerty
Message 7 of 13 in “Fix some reference-related races”
  1. 00/12 Fix some reference-related racesMichael Haggerty, Jun 20, 2013
  2. 01/12 repack_without_ref(): split list curation and entry writingMichael Haggerty, Jun 20, 2013
  3. 02/12 pack_refs(): split creation of packed refs and entry writingMichael Haggerty, Jun 20, 2013
  4. 03/12 refs: wrap the packed refs cache in a level of indirectionMichael Haggerty, Jun 20, 2013
  5. 04/12 refs: implement simple transactions for the packed-refs fileMichael Haggerty, Jun 20, 2013
  6. 05/12 refs: manage lifetime of packed refs cache via reference countingMichael Haggerty, Jun 20, 2013
  7. 06/12 do_for_each_entry(): increment the packed refs cache refcountMichael Haggerty, Jun 20, 2013
  8. 07/12 packed_ref_cache: increment refcount when lockedMichael Haggerty, Jun 20, 2013
  9. 08/12 Extract a struct stat_data from cache_entryMichael Haggerty, Jun 20, 2013
  10. 09/12 add a stat_validity structMichael Haggerty, Jun 20, 2013
  11. 10/12 get_packed_ref_cache: reload packed-refs file when it changesMichael Haggerty, Jun 20, 2013
  12. 11/12 for_each_ref: load all loose refs before packed refsMichael Haggerty, Jun 20, 2013
  13. 12/12 refs: do not invalidate the packed-refs cache unnecessarilyMichael Haggerty, Jun 20, 2013

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