Add locks to key-value pair pools

We need to ensure list and data consistency during concurrent
accesses since the interrupt handler is not executed under the
kernel lock and may add or modify entries while userland process
is reading the value or traversing the list.

1 files changed, 37 insertions, 7 deletions

diff --git a/sys/dev/pv/hypervic.c b/sys/dev/pv/hypervic.c
index bf68c26e3e4..f8027d722ea 100644
--- a/sys/dev/pv/hypervic.c
+++ b/sys/dev/pv/hypervic.c
@@ -86,6 +86,7 @@ TAILQ_HEAD(kvp_list, kvp_entry);
 
 struct kvp_pool {
 	struct kvp_list			kvp_entries;
+	struct mutex			kvp_lock;
 	u_int				kvp_index;
 };
 
@@ -538,7 +539,8 @@ static void
 kvp_pool_init(struct kvp_pool *kvpl)
 {
 	TAILQ_INIT(&kvpl->kvp_entries);
-	kvpl->kvp_index = 0xffffffffU;
+	mtx_init(&kvpl->kvp_lock, IPL_NET);
+	kvpl->kvp_index = 0;
 }
 
 static int
@@ -551,9 +553,13 @@ kvp_pool_insert(struct kvp_pool *kvpl, const char *key, const char *val,
 	if (keylen > HV_KVP_MAX_KEY_SIZE / 2)
 		return (ERANGE);
 
+	mtx_enter(&kvpl->kvp_lock);
+
 	TAILQ_FOREACH(kpe, &kvpl->kvp_entries, kpe_entry) {
-		if (strcmp(kpe->kpe_key, key) == 0)
+		if (strcmp(kpe->kpe_key, key) == 0) {
+			mtx_leave(&kvpl->kvp_lock);
 			return (EEXIST);
+		}
 	}
 
 	nkpe = pool_get(&kvp_entry_pool, PR_ZERO | PR_NOWAIT);
@@ -567,10 +573,12 @@ kvp_pool_insert(struct kvp_pool *kvpl, const char *key, const char *val,
 	else
 		memcpy(nkpe->kpe_val, val, vallen);
 
-	nkpe->kpe_index = atomic_inc_int_nv(&kvpl->kvp_index) & MAXPOOLENTS;
+	nkpe->kpe_index = kvpl->kvp_index++ & MAXPOOLENTS;
 
 	TAILQ_INSERT_TAIL(&kvpl->kvp_entries, nkpe, kpe_entry);
 
+	mtx_leave(&kvpl->kvp_lock);
+
 	return (0);
 }
 
@@ -584,18 +592,24 @@ kvp_pool_update(struct kvp_pool *kvpl, const char *key, const char *val,
 	if (keylen > HV_KVP_MAX_KEY_SIZE / 2)
 		return (ERANGE);
 
+	mtx_enter(&kvpl->kvp_lock);
+
 	TAILQ_FOREACH(kpe, &kvpl->kvp_entries, kpe_entry) {
 		if (strcmp(kpe->kpe_key, key) == 0)
 			break;
 	}
-	if (kpe == NULL)
+	if (kpe == NULL) {
+		mtx_leave(&kvpl->kvp_lock);
 		return (ENOENT);
+	}
 
 	if ((kpe->kpe_valtype = valtype) == HV_KVP_REG_SZ)
 		strlcpy(kpe->kpe_val, val, HV_KVP_MAX_KEY_SIZE / 2);
 	else
 		memcpy(kpe->kpe_val, val, vallen);
 
+	mtx_leave(&kvpl->kvp_lock);
+
 	return (0);
 }
 
@@ -615,8 +629,11 @@ kvp_pool_import(struct kvp_pool *kvpl, const char *key, uint32_t keylen,
 
 	copyin_utf16le(nkpe->kpe_key, key, HV_KVP_MAX_KEY_SIZE / 2, keylen);
 
+	mtx_enter(&kvpl->kvp_lock);
+
 	TAILQ_FOREACH(kpe, &kvpl->kvp_entries, kpe_entry) {
 		if (strcmp(kpe->kpe_key, nkpe->kpe_key) == 0) {
+			mtx_leave(&kvpl->kvp_lock);
 			pool_put(&kvp_entry_pool, nkpe);
 			return (EEXIST);
 		}
@@ -625,9 +642,10 @@ kvp_pool_import(struct kvp_pool *kvpl, const char *key, uint32_t keylen,
 	copyin_utf16le(nkpe->kpe_val, val, HV_KVP_MAX_VAL_SIZE / 2, vallen);
 	nkpe->kpe_valtype = valtype;
 
-	nkpe->kpe_index = atomic_inc_int_nv(&kvpl->kvp_index) & MAXPOOLENTS;
+	nkpe->kpe_index = kvpl->kvp_index++ & MAXPOOLENTS;
 
 	TAILQ_INSERT_TAIL(&kvpl->kvp_entries, nkpe, kpe_entry);
+	mtx_leave(&kvpl->kvp_lock);
 
 	return (0);
 }
@@ -638,12 +656,16 @@ kvp_pool_export(struct kvp_pool *kvpl, uint32_t index, char *key,
 {
 	struct kvp_entry *kpe;
 
+	mtx_enter(&kvpl->kvp_lock);
+
 	TAILQ_FOREACH(kpe, &kvpl->kvp_entries, kpe_entry) {
 		if (kpe->kpe_index == index)
 			break;
 	}
-	if (kpe == NULL)
+	if (kpe == NULL) {
+		mtx_leave(&kvpl->kvp_lock);
 		return (ENOENT);
+	}
 
 	*keylen = copyout_utf16le(key, kpe->kpe_key, HV_KVP_MAX_KEY_SIZE,
 	    strlen(kpe->kpe_key) + 1);
@@ -651,6 +673,8 @@ kvp_pool_export(struct kvp_pool *kvpl, uint32_t index, char *key,
 	    strlen(kpe->kpe_val) + 1);
 	*valtype = kpe->kpe_valtype;
 
+	mtx_leave(&kvpl->kvp_lock);
+
 	return (0);
 }
 
@@ -663,12 +687,16 @@ kvp_pool_extract(struct kvp_pool *kvpl, const char *key, char *val,
 	if (vallen < HV_KVP_MAX_VAL_SIZE / 2)
 		return (ERANGE);
 
+	mtx_enter(&kvpl->kvp_lock);
+
 	TAILQ_FOREACH(kpe, &kvpl->kvp_entries, kpe_entry) {
 		if (strcmp(kpe->kpe_key, key) == 0)
 			break;
 	}
-	if (kpe == NULL)
+	if (kpe == NULL) {
+		mtx_leave(&kvpl->kvp_lock);
 		return (ENOENT);
+	}
 
 	switch (kpe->kpe_valtype) {
 	case HV_KVP_REG_SZ:
@@ -684,6 +712,8 @@ kvp_pool_extract(struct kvp_pool *kvpl, const char *key, char *val,
 		break;
 	}
 
+	mtx_leave(&kvpl->kvp_lock);
+
 	return (0);
 }