drbd: Proper locking for updates to net_conf under RCU
Removing the get_net_conf()/put_net_conf() functions
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 59f9af9..397f977 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -3138,6 +3138,7 @@
unsigned int header_size, data_size, exp_max_sz;
struct crypto_hash *verify_tfm = NULL;
struct crypto_hash *csums_tfm = NULL;
+ struct net_conf *old_conf, *new_conf = NULL;
const int apv = tconn->agreed_pro_version;
int *rs_plan_s = NULL;
int fifo_size = 0;
@@ -3212,10 +3213,13 @@
p->csums_alg[SHARED_SECRET_MAX-1] = 0;
}
- if (strcmp(mdev->tconn->net_conf->verify_alg, p->verify_alg)) {
+ mutex_lock(&mdev->tconn->net_conf_update);
+ old_conf = mdev->tconn->net_conf;
+
+ if (strcmp(old_conf->verify_alg, p->verify_alg)) {
if (mdev->state.conn == C_WF_REPORT_PARAMS) {
dev_err(DEV, "Different verify-alg settings. me=\"%s\" peer=\"%s\"\n",
- mdev->tconn->net_conf->verify_alg, p->verify_alg);
+ old_conf->verify_alg, p->verify_alg);
goto disconnect;
}
verify_tfm = drbd_crypto_alloc_digest_safe(mdev,
@@ -3226,10 +3230,10 @@
}
}
- if (apv >= 89 && strcmp(mdev->tconn->net_conf->csums_alg, p->csums_alg)) {
+ if (apv >= 89 && strcmp(old_conf->csums_alg, p->csums_alg)) {
if (mdev->state.conn == C_WF_REPORT_PARAMS) {
dev_err(DEV, "Different csums-alg settings. me=\"%s\" peer=\"%s\"\n",
- mdev->tconn->net_conf->csums_alg, p->csums_alg);
+ old_conf->csums_alg, p->csums_alg);
goto disconnect;
}
csums_tfm = drbd_crypto_alloc_digest_safe(mdev,
@@ -3259,22 +3263,38 @@
put_ldev(mdev);
}
+ if (verify_tfm || csums_tfm) {
+ new_conf = kzalloc(sizeof(struct net_conf), GFP_KERNEL);
+ if (!new_conf) {
+ dev_err(DEV, "Allocation of new net_conf failed\n");
+ goto disconnect;
+ }
+
+ *new_conf = *old_conf;
+
+ if (verify_tfm) {
+ strcpy(new_conf->verify_alg, p->verify_alg);
+ new_conf->verify_alg_len = strlen(p->verify_alg) + 1;
+ crypto_free_hash(mdev->tconn->verify_tfm);
+ mdev->tconn->verify_tfm = verify_tfm;
+ dev_info(DEV, "using verify-alg: \"%s\"\n", p->verify_alg);
+ }
+ if (csums_tfm) {
+ strcpy(new_conf->csums_alg, p->csums_alg);
+ new_conf->csums_alg_len = strlen(p->csums_alg) + 1;
+ crypto_free_hash(mdev->tconn->csums_tfm);
+ mdev->tconn->csums_tfm = csums_tfm;
+ dev_info(DEV, "using csums-alg: \"%s\"\n", p->csums_alg);
+ }
+ rcu_assign_pointer(tconn->net_conf, new_conf);
+ }
+ mutex_unlock(&mdev->tconn->net_conf_update);
+ if (new_conf) {
+ synchronize_rcu();
+ kfree(old_conf);
+ }
+
spin_lock(&mdev->peer_seq_lock);
- /* lock against drbd_nl_syncer_conf() */
- if (verify_tfm) {
- strcpy(mdev->tconn->net_conf->verify_alg, p->verify_alg);
- mdev->tconn->net_conf->verify_alg_len = strlen(p->verify_alg) + 1;
- crypto_free_hash(mdev->tconn->verify_tfm);
- mdev->tconn->verify_tfm = verify_tfm;
- dev_info(DEV, "using verify-alg: \"%s\"\n", p->verify_alg);
- }
- if (csums_tfm) {
- strcpy(mdev->tconn->net_conf->csums_alg, p->csums_alg);
- mdev->tconn->net_conf->csums_alg_len = strlen(p->csums_alg) + 1;
- crypto_free_hash(mdev->tconn->csums_tfm);
- mdev->tconn->csums_tfm = csums_tfm;
- dev_info(DEV, "using csums-alg: \"%s\"\n", p->csums_alg);
- }
if (fifo_size != mdev->rs_plan_s.size) {
kfree(mdev->rs_plan_s.values);
mdev->rs_plan_s.values = rs_plan_s;
@@ -3286,6 +3306,7 @@
return 0;
disconnect:
+ mutex_unlock(&mdev->tconn->net_conf_update);
/* just for completeness: actually not needed,
* as this is not reached if csums_tfm was ok. */
crypto_free_hash(csums_tfm);
@@ -3715,7 +3736,9 @@
}
}
- mdev->tconn->net_conf->want_lose = 0;
+ mutex_lock(&mdev->tconn->net_conf_update);
+ mdev->tconn->net_conf->want_lose = 0; /* without copy; single bit op is atomic */
+ mutex_unlock(&mdev->tconn->net_conf_update);
drbd_md_sync(mdev); /* update connected indicator, la_size, ... */
@@ -4183,13 +4206,17 @@
spin_unlock_irq(&tconn->req_lock);
if (oc == C_DISCONNECTING) {
- wait_event(tconn->net_cnt_wait, atomic_read(&tconn->net_cnt) == 0);
+ struct net_conf *old_conf;
- crypto_free_hash(tconn->cram_hmac_tfm);
- tconn->cram_hmac_tfm = NULL;
+ mutex_lock(&tconn->net_conf_update);
+ old_conf = tconn->net_conf;
+ rcu_assign_pointer(tconn->net_conf, NULL);
+ conn_free_crypto(tconn);
+ mutex_unlock(&tconn->net_conf_update);
- kfree(tconn->net_conf);
- tconn->net_conf = NULL;
+ synchronize_rcu();
+ kfree(old_conf);
+
conn_request_state(tconn, NS(conn, C_STANDALONE), CS_VERBOSE);
}
}
@@ -4568,12 +4595,8 @@
}
} while (h == 0);
- if (h > 0) {
- if (get_net_conf(tconn)) {
- drbdd(tconn);
- put_net_conf(tconn);
- }
- }
+ if (h > 0)
+ drbdd(tconn);
drbd_disconnect(tconn);