170 lines
4.2 KiB
Diff
170 lines
4.2 KiB
Diff
autofs-5.1.8 - fix deadlock with hosts map reload
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From: Ian Kent <raven@themaw.net>
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When reloading maps the hosts map calls lookup method ->parse_mount()
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for each multi-mount root entry in the map (each host) while holding
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the cache read lock which leads to a cache lock deadlock.
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Remove the need to hold the cache read lock by creating an independent
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list of entries for the update so the lock doesn't need to be taken.
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Signed-off-by: Ian Kent <raven@themaw.net>
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---
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CHANGELOG | 1
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modules/lookup_hosts.c | 100 ++++++++++++++++++++++++++++++++++++++++---------
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2 files changed, 83 insertions(+), 18 deletions(-)
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--- autofs-5.1.4.orig/CHANGELOG
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+++ autofs-5.1.4/CHANGELOG
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@@ -100,6 +100,7 @@
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- serialise lookup module open and reinit.
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- coverity fix for invalid access.
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- fix hosts map deadlock on restart.
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+- fix deadlock with hosts map reload.
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xx/xx/2018 autofs-5.1.5
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- fix flag file permission.
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--- autofs-5.1.4.orig/modules/lookup_hosts.c
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+++ autofs-5.1.4/modules/lookup_hosts.c
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@@ -201,10 +201,72 @@ static int do_parse_mount(struct autofs_
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return NSS_STATUS_SUCCESS;
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}
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+struct update_context {
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+ char *key;
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+ int key_len;
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+ char *entry;
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+ struct update_context *next;
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+};
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+
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+static int add_update_entry(struct update_context **entries, struct mapent *me)
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+{
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+ struct update_context *upd;
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+ char *key, *ent;
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+
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+ key = strdup(me->key);
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+ if (!key)
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+ return 0;
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+
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+ ent = strdup(me->mapent);
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+ if (!ent) {
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+ free(key);
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+ return 0;
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+ }
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+
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+ upd = malloc(sizeof(struct update_context));
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+ if (!upd) {
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+ free(ent);
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+ free(key);
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+ return 0;
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+ }
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+
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+ upd->key = key;
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+ upd->key_len = me->len;
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+ upd->entry = ent;
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+ upd->next = NULL;
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+ if (*entries)
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+ (*entries)->next = upd;
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+ *entries = upd;
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+
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+ return 1;
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+}
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+
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+static void free_update_entries(struct update_context *entries)
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+{
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+ struct update_context *this = entries;
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+
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+ while (this) {
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+ struct update_context *next = this->next;
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+ free(this->key);
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+ free(this->entry);
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+ free(this);
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+ this = next;
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+ }
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+}
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+
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+void entries_cleanup(void *arg)
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+{
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+ struct update_context *entries = arg;
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+
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+ free_update_entries(entries);
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+}
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+
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static void update_hosts_mounts(struct autofs_point *ap,
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struct map_source *source, time_t age,
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struct lookup_context *ctxt)
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{
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+ struct update_context *head = NULL;
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+ struct update_context *entries = NULL;
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struct mapent_cache *mc;
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struct mapent *me;
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char *mapent;
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@@ -212,6 +274,8 @@ static void update_hosts_mounts(struct a
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mc = source->mc;
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+ pthread_cleanup_push(entries_cleanup, head);
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+
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pthread_cleanup_push(cache_lock_cleanup, mc);
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cache_writelock(mc);
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me = cache_lookup_first(mc);
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@@ -224,39 +288,39 @@ static void update_hosts_mounts(struct a
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mapent = get_exports(ap, me->key);
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if (mapent) {
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- cache_update(mc, source, me->key, mapent, age);
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+ int ret;
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+
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+ ret = cache_update(mc, source, me->key, mapent, age);
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free(mapent);
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+ if (!IS_MM_ROOT(me))
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+ goto next;
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+ if (ret != CHE_FAIL) {
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+ if (!add_update_entry(&entries, me))
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+ warn(ap->logopt, MODPREFIX
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+ "failed to add update entry for %s", me->key);
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+ else if (!head)
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+ head = entries;
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+ }
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}
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next:
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me = cache_lookup_next(mc, me);
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}
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pthread_cleanup_pop(1);
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- pthread_cleanup_push(cache_lock_cleanup, mc);
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- cache_readlock(mc);
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- me = cache_lookup_first(mc);
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- while (me) {
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- /*
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- * Hosts map entry not yet expanded, already expired
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- * or not the base of the tree
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- */
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- if (!IS_MM(me) || !IS_MM_ROOT(me))
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- goto cont;
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-
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+ while (head) {
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debug(ap->logopt, MODPREFIX
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- "attempt to update exports for %s", me->key);
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+ "attempt to update exports for %s", head->key);
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master_source_current_wait(ap->entry);
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ap->entry->current = source;
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ap->flags |= MOUNT_FLAG_REMOUNT;
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- ret = ctxt->parse->parse_mount(ap, me->key, strlen(me->key),
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- me->mapent, ctxt->parse->context);
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+ ret = ctxt->parse->parse_mount(ap, head->key, strlen(head->key),
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+ head->entry, ctxt->parse->context);
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if (ret)
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warn(ap->logopt, MODPREFIX
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- "failed to parse mount %s", me->mapent);
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+ "failed to parse mount %s", head->entry);
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ap->flags &= ~MOUNT_FLAG_REMOUNT;
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-cont:
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- me = cache_lookup_next(mc, me);
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+ head = head->next;
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}
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pthread_cleanup_pop(1);
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}
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