Note bucket lock requirements and move REQUIRE inside locked section.

(cherry picked from commit 13aaeaa06f79e520a0b18a431dfe449d2edf4476)

diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 6f672a13a85ea7fb8aae62d1c5f3443b4f1daec1..0bcfc227eb02d1ef829b37434d137db7129648fe 100644 (file)
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -319,7 +319,7 @@ struct fetchctx {
        /*%
         * The number of events we're waiting for.
         */
-       unsigned int                    pending;
+       unsigned int                    pending;        /* Bucket lock. */
 
        /*%
         * The number of times we've "restarted" the current
@@ -348,7 +348,7 @@ struct fetchctx {
        /*%
         * Number of queries that reference this context.
         */
-       unsigned int                    nqueries;
+       unsigned int                    nqueries;       /* Bucket lock. */
 
        /*%
         * The reason to print when logging a successful
@@ -393,7 +393,7 @@ struct fetchctx {
 #define FCTX_ATTR_HAVEANSWER            0x0001
 #define FCTX_ATTR_GLUING                0x0002
 #define FCTX_ATTR_ADDRWAIT              0x0004
-#define FCTX_ATTR_SHUTTINGDOWN          0x0008
+#define FCTX_ATTR_SHUTTINGDOWN          0x0008         /* Bucket lock */
 #define FCTX_ATTR_WANTCACHE             0x0010
 #define FCTX_ATTR_WANTNCACHE            0x0020
 #define FCTX_ATTR_NEEDEDNS0             0x0040
@@ -5353,11 +5353,12 @@ maybe_destroy(fetchctx_t *fctx, bool locked) {
        dns_validator_t *validator, *next_validator;
        bool dodestroy = false;
 
-       REQUIRE(SHUTTINGDOWN(fctx));
-
        bucketnum = fctx->bucketnum;
        if (!locked)
                LOCK(&res->buckets[bucketnum].lock);
+
+       REQUIRE(SHUTTINGDOWN(fctx));
+
        if (fctx->pending != 0 || fctx->nqueries != 0)
                goto unlock;
 
@@ -7064,6 +7065,9 @@ fctx_increference(fetchctx_t *fctx) {
        UNLOCK(&fctx->res->buckets[fctx->bucketnum].lock);
 }
 
+/*
+ * Requires bucket lock to be held.
+ */
 static bool
 fctx_decreference(fetchctx_t *fctx) {
        bool bucket_empty = false;