global: replace rwlock with mtx if never rlocked

There were multiple places where a rwlock was used despite never
rlocking, so just change these into mtxs. This was done with the aid of
Coccinelle's spatch, using this input:

    #spatch -j 4 --recursive-includes --include-headers-for-types --include-headers --in-place --macro-file <seebelow.h>

    virtual after_start

    @initialize:ocaml@
    @@

    let has_write_table = Hashtbl.create 101
    let has_read_table = Hashtbl.create 101

    let ok i m =
      let entry = (i,m) in
      Hashtbl.mem has_write_table entry && not(Hashtbl.mem has_read_table entry)

    @hasw depends on !after_start@
    identifier i,m;
    struct i x;
    @@

    (
    rw_wlock(&x.m)
    |
    rw_wunlock(&x.m)
    )

    @script:ocaml@
    i << hasw.i;
    m << hasw.m;
    @@
    Hashtbl.replace has_write_table (i,m) ()

    @hasr depends on !after_start@
    identifier i,m;
    struct i x;
    @@

    (
    rw_rlock(&x.m)
    |
    rw_runlock(&x.m)
    )

    @script:ocaml@
    i << hasr.i;
    m << hasr.m;
    @@
    Hashtbl.replace has_read_table (i,m) ()

    @finalize:ocaml depends on !after_start@
    wt << merge.has_write_table;
    rt << merge.has_read_table;
    @@

    let redo ts dst =
      List.iter (Hashtbl.iter (fun k _ -> Hashtbl.add dst k ())) ts in
    redo wt has_write_table;
    redo rt has_read_table;

    let it = new iteration() in
    it#add_virtual_rule After_start;
    it#register()

    (* ----------------------------------------------------------- *)

    @depends on after_start@
    identifier i;
    identifier m : script:ocaml(i) { ok i m };
    @@

    struct i {
      ...
    - struct rwlock m;
    + struct mtx m;
      ...
    }

    @depends on after_start disable fld_to_ptr@
    identifier m;
    identifier i : script:ocaml(m) { ok i m };
    struct i x;
    @@

    - rw_wlock
    + mtx_lock
       (&x.m)

    @depends on after_start disable fld_to_ptr@
    identifier m;
    identifier i : script:ocaml(m) { ok i m };
    struct i x;
    @@

    - rw_wunlock
    + mtx_unlock
       (&x.m)

    @depends on after_start disable fld_to_ptr@
    identifier m;
    expression e;
    identifier i : script:ocaml(m) { ok i m };
    struct i x;
    @@

    - rw_init(&x.m, e);
    + mtx_init(&x.m, e, NULL, MTX_DEF);

    @depends on after_start disable fld_to_ptr@
    identifier m;
    identifier i : script:ocaml(m) { ok i m };
    struct i x;
    @@

    - rw_destroy
    + mtx_destroy
       (&x.m)

    @depends on after_start disable fld_to_ptr, ptr_to_array@
    identifier m;
    identifier i : script:ocaml(m) { ok i m };
    struct i *x;
    @@

    - rw_wlock
    + mtx_lock
       (&x->m)

    @depends on after_start disable fld_to_ptr, ptr_to_array@
    identifier m;
    identifier i : script:ocaml(m) { ok i m };
    struct i *x;
    @@

    - rw_wunlock
    + mtx_unlock
       (&x->m)

    @depends on after_start disable fld_to_ptr, ptr_to_array@
    identifier m;
    expression e;
    identifier i : script:ocaml(m) { ok i m };
    struct i *x;
    @@

    - rw_init(&x->m, e);
    + mtx_init(&x->m, e, NULL, MTX_DEF);

    @depends on after_start disable fld_to_ptr, ptr_to_array@
    identifier m;
    identifier i : script:ocaml(m) { ok i m };
    struct i *x;
    @@

    - rw_destroy
    + mtx_destroy
       (&x->m)

A few macros needed to be provided manually for the parser to work:

    #define LIST_HEAD(x,y) int
    #define TAILQ_HEAD(x,y) int
    #define STAILQ_HEAD(x,y) int
    #define CK_LIST_HEAD(x,y) int
    #define CK_LIST_ENTRY(x) int
    #define LIST_ENTRY(x) int
    #define TAILQ_ENTRY(x) int
    #define STAILQ_ENTRY(x) int

Co-authored-by: Julia Lawall <julia.lawall@inria.fr>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

TODO.md

@@ -10,7 +10,6 @@
 - Review all included headers, and minimize a bit.
 - Figure out clear locking rules for network stack stuff -- when different
   functions run under what locks and what they race with.
-- There are a few rwlocks that only ever wlock. Make these mtx instead.
 
 ### Crypto TODO
 

src/wg_cookie.c

@@ -47,7 +47,7 @@ struct ratelimit_entry {
 
 struct ratelimit {
 	uint8_t				rl_secret[SIPHASH_KEY_LENGTH];
-	struct rwlock			rl_lock;
+	struct mtx			rl_mtx;
 	struct callout			rl_gc;
 	LIST_HEAD(, ratelimit_entry)	rl_table[RATELIMIT_SIZE];
 	size_t				rl_table_num;
@@ -107,14 +107,14 @@ cookie_checker_init(struct cookie_checker *cc)
 	bzero(cc, sizeof(*cc));
 
 	rw_init(&cc->cc_key_lock, "cookie_checker_key");
-	rw_init(&cc->cc_secret_lock, "cookie_checker_secret");
+	mtx_init(&cc->cc_secret_mtx, "cookie_checker_secret", NULL, MTX_DEF);
 }
 
 void
 cookie_checker_free(struct cookie_checker *cc)
 {
 	rw_destroy(&cc->cc_key_lock);
-	rw_destroy(&cc->cc_secret_lock);
+	mtx_destroy(&cc->cc_secret_mtx);
 	explicit_bzero(cc, sizeof(*cc));
 }
 
@@ -307,7 +307,7 @@ make_cookie(struct cookie_checker *cc, uint8_t cookie[COOKIE_COOKIE_SIZE],
 {
 	struct blake2s_state state;
 
-	rw_wlock(&cc->cc_secret_lock);
+	mtx_lock(&cc->cc_secret_mtx);
 	if (timer_expired(cc->cc_secret_birthdate,
 	    COOKIE_SECRET_MAX_AGE, 0)) {
 		arc4random_buf(cc->cc_secret, COOKIE_SECRET_SIZE);
@@ -315,7 +315,7 @@ make_cookie(struct cookie_checker *cc, uint8_t cookie[COOKIE_COOKIE_SIZE],
 	}
 	blake2s_init_key(&state, COOKIE_COOKIE_SIZE, cc->cc_secret,
 	    COOKIE_SECRET_SIZE);
-	rw_wunlock(&cc->cc_secret_lock);
+	mtx_unlock(&cc->cc_secret_mtx);
 
 	if (sa->sa_family == AF_INET) {
 		blake2s_update(&state, (uint8_t *)&satosin(sa)->sin_addr,
@@ -340,8 +340,8 @@ static void
 ratelimit_init(struct ratelimit *rl)
 {
 	size_t i;
-	rw_init(&rl->rl_lock, "ratelimit_lock");
-	callout_init_rw(&rl->rl_gc, &rl->rl_lock, 0);
+	mtx_init(&rl->rl_mtx, "ratelimit_lock", NULL, MTX_DEF);
+	callout_init_rw(&rl->rl_gc, &rl->rl_mtx, 0);
 	arc4random_buf(rl->rl_secret, sizeof(rl->rl_secret));
 	for (i = 0; i < RATELIMIT_SIZE; i++)
 		LIST_INIT(&rl->rl_table[i]);
@@ -351,17 +351,17 @@ ratelimit_init(struct ratelimit *rl)
 static void
 ratelimit_deinit(struct ratelimit *rl)
 {
-	rw_wlock(&rl->rl_lock);
+	mtx_lock(&rl->rl_mtx);
 	callout_stop(&rl->rl_gc);
 	ratelimit_gc(rl, true);
-	rw_wunlock(&rl->rl_lock);
-	rw_destroy(&rl->rl_lock);
+	mtx_unlock(&rl->rl_mtx);
+	mtx_destroy(&rl->rl_mtx);
 }
 
 static void
 ratelimit_gc_callout(void *_rl)
 {
-	/* callout will wlock rl_lock for us */
+	/* callout will lock rl_mtx for us */
 	ratelimit_gc(_rl, false);
 }
 
@@ -386,7 +386,7 @@ ratelimit_gc(struct ratelimit *rl, bool force)
 	struct ratelimit_entry *r, *tr;
 	sbintime_t expiry;
 
-	rw_assert(&rl->rl_lock, RA_WLOCKED);
+	mtx_assert(&rl->rl_mtx, MA_OWNED);
 
 	if (rl->rl_table_num == 0)
 		return;
@@ -428,7 +428,7 @@ ratelimit_allow(struct ratelimit *rl, struct sockaddr *sa, struct vnet *vnet)
 		return ret;
 
 	bucket = siphash13(rl->rl_secret, &key, len) & RATELIMIT_MASK;
-	rw_wlock(&rl->rl_lock);
+	mtx_lock(&rl->rl_mtx);
 
 	LIST_FOREACH(r, &rl->rl_table[bucket], r_entry) {
 		if (bcmp(&r->r_key, &key, len) != 0)
@@ -481,7 +481,7 @@ ratelimit_allow(struct ratelimit *rl, struct sockaddr *sa, struct vnet *vnet)
 ok:
 	ret = 0;
 error:
-	rw_wunlock(&rl->rl_lock);
+	mtx_unlock(&rl->rl_mtx);
 	return ret;
 }
 

src/wg_cookie.h

@@ -45,7 +45,7 @@ struct cookie_checker {
 	uint8_t		cc_mac1_key[COOKIE_KEY_SIZE];
 	uint8_t		cc_cookie_key[COOKIE_KEY_SIZE];
 
-	struct rwlock	cc_secret_lock;
+	struct mtx	cc_secret_mtx;
 	sbintime_t	cc_secret_birthdate;	/* sbinuptime */
 	uint8_t		cc_secret[COOKIE_SECRET_SIZE];
 };

src/wg_noise.c

@@ -111,7 +111,7 @@ struct noise_remote {
 	struct noise_local		*r_local;
 	void				*r_arg;
 
-	struct rwlock			 r_keypair_lock;
+	struct mtx			 r_keypair_mtx;
 	struct noise_keypair		*r_next, *r_current, *r_previous;
 
 	struct epoch_context		 r_smr;
@@ -129,11 +129,11 @@ struct noise_local {
 	void				*l_arg;
 	void				(*l_cleanup)(struct noise_local *);
 
-	struct rwlock			 l_remote_lock;
+	struct mtx			 l_remote_mtx;
 	size_t				 l_remote_num;
 	CK_LIST_HEAD(,noise_remote)	 l_remote_hash[HT_REMOTE_SIZE];
 
-	struct rwlock			 l_index_lock;
+	struct mtx			 l_index_mtx;
 	CK_LIST_HEAD(,noise_index)	 l_index_hash[HT_INDEX_SIZE];
 };
 
@@ -195,12 +195,12 @@ noise_local_alloc(void *arg)
 	l->l_arg = arg;
 	l->l_cleanup = NULL;
 
-	rw_init(&l->l_remote_lock, "noise_remote");
+	mtx_init(&l->l_remote_mtx, "noise_remote", NULL, MTX_DEF);
 	l->l_remote_num = 0;
 	for (i = 0; i < HT_REMOTE_SIZE; i++)
 		CK_LIST_INIT(&l->l_remote_hash[i]);
 
-	rw_init(&l->l_index_lock, "noise_index");
+	mtx_init(&l->l_index_mtx, "noise_index", NULL, MTX_DEF);
 	for (i = 0; i < HT_INDEX_SIZE; i++)
 		CK_LIST_INIT(&l->l_index_hash[i]);
 
@@ -221,8 +221,8 @@ noise_local_put(struct noise_local *l)
 		if (l->l_cleanup != NULL)
 			l->l_cleanup(l);
 		rw_destroy(&l->l_identity_lock);
-		rw_destroy(&l->l_remote_lock);
-		rw_destroy(&l->l_index_lock);
+		mtx_destroy(&l->l_remote_mtx);
+		mtx_destroy(&l->l_index_mtx);
 		explicit_bzero(l, sizeof(*l));
 		free(l, M_NOISE);
 	}
@@ -311,7 +311,7 @@ noise_remote_alloc(struct noise_local *l, void *arg,
 	r->r_local = noise_local_ref(l);
 	r->r_arg = arg;
 
-	rw_init(&r->r_keypair_lock, "noise_keypair");
+	mtx_init(&r->r_keypair_mtx, "noise_keypair", NULL, MTX_DEF);
 
 	return (r);
 }
@@ -326,7 +326,7 @@ noise_remote_enable(struct noise_remote *r)
 	/* Insert to hashtable */
 	idx = siphash24(l->l_hash_key, r->r_public, NOISE_PUBLIC_KEY_LEN) & HT_REMOTE_MASK;
 
-	rw_wlock(&l->l_remote_lock);
+	mtx_lock(&l->l_remote_mtx);
 	if (!r->r_entry_inserted) {
 		if (l->l_remote_num < MAX_REMOTE_PER_LOCAL) {
 			r->r_entry_inserted = true;
@@ -336,7 +336,7 @@ noise_remote_enable(struct noise_remote *r)
 			ret = ENOSPC;
 		}
 	}
-	rw_wunlock(&l->l_remote_lock);
+	mtx_unlock(&l->l_remote_mtx);
 
 	return ret;
 }
@@ -346,13 +346,13 @@ noise_remote_disable(struct noise_remote *r)
 {
 	struct noise_local *l = r->r_local;
 	/* remove from hashtable */
-	rw_wlock(&l->l_remote_lock);
+	mtx_lock(&l->l_remote_mtx);
 	if (r->r_entry_inserted) {
 		r->r_entry_inserted = false;
 		CK_LIST_REMOVE(r, r_entry);
 		l->l_remote_num--;
 	};
-	rw_wunlock(&l->l_remote_lock);
+	mtx_unlock(&l->l_remote_mtx);
 }
 
 struct noise_remote *
@@ -394,15 +394,15 @@ assign_id:
 			goto assign_id;
 	}
 
-	rw_wlock(&l->l_index_lock);
+	mtx_lock(&l->l_index_mtx);
 	CK_LIST_FOREACH(i, &l->l_index_hash[idx], i_entry) {
 		if (i->i_local_index == r_i->i_local_index) {
-			rw_wunlock(&l->l_index_lock);
+			mtx_unlock(&l->l_index_mtx);
 			goto assign_id;
 		}
 	}
 	CK_LIST_INSERT_HEAD(&l->l_index_hash[idx], r_i, i_entry);
-	rw_wunlock(&l->l_index_lock);
+	mtx_unlock(&l->l_index_mtx);
 
 	NET_EPOCH_EXIT(et);
 }
@@ -447,10 +447,10 @@ noise_remote_index_remove(struct noise_local *l, struct noise_remote *r)
 {
 	rw_assert(&r->r_handshake_lock, RA_WLOCKED);
 	if (r->r_handshake_state != HANDSHAKE_DEAD) {
-		rw_wlock(&l->l_index_lock);
+		mtx_lock(&l->l_index_mtx);
 		r->r_handshake_state = HANDSHAKE_DEAD;
 		CK_LIST_REMOVE(&r->r_index, i_entry);
-		rw_wunlock(&l->l_index_lock);
+		mtx_unlock(&l->l_index_mtx);
 		return (1);
 	}
 	return (0);
@@ -472,7 +472,7 @@ noise_remote_smr_free(struct epoch_context *smr)
 		r->r_cleanup(r);
 	noise_local_put(r->r_local);
 	rw_destroy(&r->r_handshake_lock);
-	rw_destroy(&r->r_keypair_lock);
+	mtx_destroy(&r->r_keypair_mtx);
 	explicit_bzero(r, sizeof(*r));
 	free(r, M_NOISE);
 }
@@ -564,7 +564,7 @@ noise_remote_keypairs_clear(struct noise_remote *r)
 {
 	struct noise_keypair *kp;
 
-	rw_wlock(&r->r_keypair_lock);
+	mtx_lock(&r->r_keypair_mtx);
 	kp = ck_pr_load_ptr(&r->r_next);
 	ck_pr_store_ptr(&r->r_next, NULL);
 	noise_keypair_drop(kp);
@@ -576,7 +576,7 @@ noise_remote_keypairs_clear(struct noise_remote *r)
 	kp = ck_pr_load_ptr(&r->r_previous);
 	ck_pr_store_ptr(&r->r_previous, NULL);
 	noise_keypair_drop(kp);
-	rw_wunlock(&r->r_keypair_lock);
+	mtx_unlock(&r->r_keypair_mtx);
 }
 
 static void
@@ -606,7 +606,7 @@ noise_add_new_keypair(struct noise_local *l, struct noise_remote *r,
 	struct noise_index *r_i = &r->r_index;
 
 	/* Insert into the keypair table */
-	rw_wlock(&r->r_keypair_lock);
+	mtx_lock(&r->r_keypair_mtx);
 	next = ck_pr_load_ptr(&r->r_next);
 	current = ck_pr_load_ptr(&r->r_current);
 	previous = ck_pr_load_ptr(&r->r_previous);
@@ -628,7 +628,7 @@ noise_add_new_keypair(struct noise_local *l, struct noise_remote *r,
 		noise_keypair_drop(previous);
 
 	}
-	rw_wunlock(&r->r_keypair_lock);
+	mtx_unlock(&r->r_keypair_mtx);
 
 	/* Insert into index table */
 	rw_assert(&r->r_handshake_lock, RA_WLOCKED);
@@ -637,11 +637,11 @@ noise_add_new_keypair(struct noise_local *l, struct noise_remote *r,
 	kp->kp_index.i_local_index = r_i->i_local_index;
 	kp->kp_index.i_remote_index = r_i->i_remote_index;
 
-	rw_wlock(&l->l_index_lock);
+	mtx_lock(&l->l_index_mtx);
 	CK_LIST_INSERT_BEFORE(r_i, &kp->kp_index, i_entry);
 	r->r_handshake_state = HANDSHAKE_DEAD;
 	CK_LIST_REMOVE(r_i, i_entry);
-	rw_wunlock(&l->l_index_lock);
+	mtx_unlock(&l->l_index_mtx);
 
 	explicit_bzero(&r->r_handshake, sizeof(r->r_handshake));
 }
@@ -732,9 +732,9 @@ noise_keypair_received_with(struct noise_keypair *kp)
 	if (kp != ck_pr_load_ptr(&r->r_next))
 		return (0);
 
-	rw_wlock(&r->r_keypair_lock);
+	mtx_lock(&r->r_keypair_mtx);
 	if (kp != ck_pr_load_ptr(&r->r_next)) {
-		rw_wunlock(&r->r_keypair_lock);
+		mtx_unlock(&r->r_keypair_mtx);
 		return (0);
 	}
 
@@ -743,7 +743,7 @@ noise_keypair_received_with(struct noise_keypair *kp)
 	noise_keypair_drop(old);
 	ck_pr_store_ptr(&r->r_current, kp);
 	ck_pr_store_ptr(&r->r_next, NULL);
-	rw_wunlock(&r->r_keypair_lock);
+	mtx_unlock(&r->r_keypair_mtx);
 
 	return (ECONNRESET);
 }
@@ -778,9 +778,9 @@ noise_keypair_drop(struct noise_keypair *kp)
 	r = kp->kp_remote;
 	l = r->r_local;
 
-	rw_wlock(&l->l_index_lock);
+	mtx_lock(&l->l_index_mtx);
 	CK_LIST_REMOVE(&kp->kp_index, i_entry);
-	rw_wunlock(&l->l_index_lock);
+	mtx_unlock(&l->l_index_mtx);
 
 	noise_keypair_put(kp);
 }