From: Bruno Faccini <bruno.faccini@intel.com>
Date: Wed, 17 Dec 2014 09:57:07 +0000 (+0100)
Subject: LU-5264 obdclass: fix race during key quiescency
X-Git-Tag: 2.7.51~84
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=refs%2Fchanges%2F03%2F13103%2F3;p=fs%2Flustre-release.git

LU-5264 obdclass: fix race during key quiescency

Upon umount, presumably of last device using same OSD back-end,
to prepare for module unload, lu_context_key_quiesce() is run to
remove all module's key reference in any context linked on
lu_context_remembered list.
Threads must protect against such transversal processing when
exiting from its context.

Signed-off-by: Bruno Faccini <bruno.faccini@intel.com>
Change-Id: If2c8199fa764236308b49950672129a63b8877f5
Reviewed-on: http://review.whamcloud.com/13103
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
---

diff --git a/lustre/obdclass/lu_object.c b/lustre/obdclass/lu_object.c
index 337069b..dac8c2a 100644
--- a/lustre/obdclass/lu_object.c
+++ b/lustre/obdclass/lu_object.c
@@ -1721,15 +1721,20 @@ void lu_context_exit(struct lu_context *ctx)
         ctx->lc_state = LCS_LEFT;
         if (ctx->lc_tags & LCT_HAS_EXIT && ctx->lc_value != NULL) {
                 for (i = 0; i < ARRAY_SIZE(lu_keys); ++i) {
-                        if (ctx->lc_value[i] != NULL) {
-                                struct lu_context_key *key;
-
-                                key = lu_keys[i];
-                                LASSERT(key != NULL);
-                                if (key->lct_exit != NULL)
-                                        key->lct_exit(ctx,
-                                                      key, ctx->lc_value[i]);
-                        }
+			/* could race with key quiescency */
+			if (ctx->lc_tags & LCT_REMEMBER)
+				spin_lock(&lu_keys_guard);
+			if (ctx->lc_value[i] != NULL) {
+				struct lu_context_key *key;
+
+				key = lu_keys[i];
+				LASSERT(key != NULL);
+				if (key->lct_exit != NULL)
+					key->lct_exit(ctx,
+						      key, ctx->lc_value[i]);
+			}
+			if (ctx->lc_tags & LCT_REMEMBER)
+				spin_unlock(&lu_keys_guard);
                 }
         }
 }