Merge branch 'ph/pack-objects-mutex-fix'

"git pack-objects" incorrectly used uninitialized mutex, which has
been corrected.

* ph/pack-objects-mutex-fix:
  pack-objects: merge read_lock and lock in packing_data struct
  pack-objects: move read mutex to packing_data struct

builtin/pack-objects.c

@@ -1953,11 +1953,6 @@ static int delta_cacheable(unsigned long src_size, unsigned long trg_size,
 	return 0;
 }
 
-/* Protect access to object database */
-static pthread_mutex_t read_mutex;
-#define read_lock()		pthread_mutex_lock(&read_mutex)
-#define read_unlock()		pthread_mutex_unlock(&read_mutex)
-
 /* Protect delta_cache_size */
 static pthread_mutex_t cache_mutex;
 #define cache_lock()		pthread_mutex_lock(&cache_mutex)
@@ -1993,11 +1988,11 @@ unsigned long oe_get_size_slow(struct packing_data *pack,
 	unsigned long used, avail, size;
 
 	if (e->type_ != OBJ_OFS_DELTA && e->type_ != OBJ_REF_DELTA) {
-		read_lock();
+		packing_data_lock(&to_pack);
 		if (oid_object_info(the_repository, &e->idx.oid, &size) < 0)
 			die(_("unable to get size of %s"),
 			    oid_to_hex(&e->idx.oid));
-		read_unlock();
+		packing_data_unlock(&to_pack);
 		return size;
 	}
 
@@ -2005,7 +2000,7 @@ unsigned long oe_get_size_slow(struct packing_data *pack,
 	if (!p)
 		BUG("when e->type is a delta, it must belong to a pack");
 
-	read_lock();
+	packing_data_lock(&to_pack);
 	w_curs = NULL;
 	buf = use_pack(p, &w_curs, e->in_pack_offset, &avail);
 	used = unpack_object_header_buffer(buf, avail, &type, &size);
@@ -2014,7 +2009,7 @@ unsigned long oe_get_size_slow(struct packing_data *pack,
 		    oid_to_hex(&e->idx.oid));
 
 	unuse_pack(&w_curs);
-	read_unlock();
+	packing_data_unlock(&to_pack);
 	return size;
 }
 
@@ -2076,9 +2071,9 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
 
 	/* Load data if not already done */
 	if (!trg->data) {
-		read_lock();
+		packing_data_lock(&to_pack);
 		trg->data = read_object_file(&trg_entry->idx.oid, &type, &sz);
-		read_unlock();
+		packing_data_unlock(&to_pack);
 		if (!trg->data)
 			die(_("object %s cannot be read"),
 			    oid_to_hex(&trg_entry->idx.oid));
@@ -2089,9 +2084,9 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
 		*mem_usage += sz;
 	}
 	if (!src->data) {
-		read_lock();
+		packing_data_lock(&to_pack);
 		src->data = read_object_file(&src_entry->idx.oid, &type, &sz);
-		read_unlock();
+		packing_data_unlock(&to_pack);
 		if (!src->data) {
 			if (src_entry->preferred_base) {
 				static int warned = 0;
@@ -2337,9 +2332,9 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
 
 static void try_to_free_from_threads(size_t size)
 {
-	read_lock();
+	packing_data_lock(&to_pack);
 	release_pack_memory(size);
-	read_unlock();
+	packing_data_unlock(&to_pack);
 }
 
 static try_to_free_t old_try_to_free_routine;
@@ -2381,7 +2376,6 @@ static pthread_cond_t progress_cond;
  */
 static void init_threaded_search(void)
 {
-	init_recursive_mutex(&read_mutex);
 	pthread_mutex_init(&cache_mutex, NULL);
 	pthread_mutex_init(&progress_mutex, NULL);
 	pthread_cond_init(&progress_cond, NULL);
@@ -2392,7 +2386,6 @@ static void cleanup_threaded_search(void)
 {
 	set_try_to_free_routine(old_try_to_free_routine);
 	pthread_cond_destroy(&progress_cond);
-	pthread_mutex_destroy(&read_mutex);
 	pthread_mutex_destroy(&cache_mutex);
 	pthread_mutex_destroy(&progress_mutex);
 }

pack-objects.c

@@ -150,9 +150,7 @@ void prepare_packing_data(struct repository *r, struct packing_data *pdata)
 					     1U << OE_SIZE_BITS);
 	pdata->oe_delta_size_limit = git_env_ulong("GIT_TEST_OE_DELTA_SIZE",
 						   1UL << OE_DELTA_SIZE_BITS);
-#ifndef NO_PTHREADS
+	init_recursive_mutex(&pdata->odb_lock);
-	pthread_mutex_init(&pdata->lock, NULL);
-#endif
 }
 
 struct object_entry *packlist_alloc(struct packing_data *pdata,

pack-objects.h

@@ -148,7 +148,11 @@ struct packing_data {
 	struct packed_git **in_pack_by_idx;
 	struct packed_git **in_pack;
 
-	pthread_mutex_t lock;
+	/*
+	 * During packing with multiple threads, protect the in-core
+	 * object database from concurrent accesses.
+	 */
+	pthread_mutex_t odb_lock;
 
 	/*
 	 * This list contains entries for bases which we know the other side
@@ -168,13 +172,14 @@ struct packing_data {
 
 void prepare_packing_data(struct repository *r, struct packing_data *pdata);
 
+/* Protect access to object database */
 static inline void packing_data_lock(struct packing_data *pdata)
 {
-	pthread_mutex_lock(&pdata->lock);
+	pthread_mutex_lock(&pdata->odb_lock);
 }
 static inline void packing_data_unlock(struct packing_data *pdata)
 {
-	pthread_mutex_unlock(&pdata->lock);
+	pthread_mutex_unlock(&pdata->odb_lock);
 }
 
 struct object_entry *packlist_alloc(struct packing_data *pdata,