Merge branch 'net-tls-add-a-TX-lock'

Jakub Kicinski says:

====================
net/tls: add a TX lock

Some time ago Pooja and Mallesham started reporting crashes with
an async accelerator. After trying to poke the existing logic into
shape I came to the conclusion that it can't be trusted, and to
preserve our sanity we should just add a lock around the TX side.

First patch removes the sk_write_pending checks from the write
space callbacks. Those don't seem to have a logical justification.

Patch 2 adds the TX lock and patch 3 associated test (which should
hang with current net).

Mallesham reports that even with these fixes applied the async
accelerator workload still occasionally hangs waiting for socket
memory. I suspect that's strictly related to the way async crypto
is integrated in TLS, so I think we should get these into net or
net-next and move from there.
====================

Signed-off-by: David S. Miller <[email protected]>

include/net/tls.h

@@ -40,6 +40,7 @@
 #include <linux/socket.h>
 #include <linux/tcp.h>
 #include <linux/skmsg.h>
+#include <linux/mutex.h>
 #include <linux/netdevice.h>
 #include <linux/rcupdate.h>
 
@@ -269,6 +270,10 @@ struct tls_context {
 
 	bool in_tcp_sendpages;
 	bool pending_open_record_frags;
+
+	struct mutex tx_lock; /* protects partially_sent_* fields and
+			       * per-type TX fields
+			       */
 	unsigned long flags;
 
 	/* cache cold stuff */

net/tls/tls_device.c

@@ -523,8 +523,10 @@ static int tls_push_data(struct sock *sk,
 int tls_device_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 {
 	unsigned char record_type = TLS_RECORD_TYPE_DATA;
+	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	int rc;
 
+	mutex_lock(&tls_ctx->tx_lock);
 	lock_sock(sk);
 
 	if (unlikely(msg->msg_controllen)) {
@@ -538,12 +540,14 @@ int tls_device_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 
 out:
 	release_sock(sk);
+	mutex_unlock(&tls_ctx->tx_lock);
 	return rc;
 }
 
 int tls_device_sendpage(struct sock *sk, struct page *page,
 			int offset, size_t size, int flags)
 {
+	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct iov_iter	msg_iter;
 	char *kaddr = kmap(page);
 	struct kvec iov;
@@ -552,6 +556,7 @@ int tls_device_sendpage(struct sock *sk, struct page *page,
 	if (flags & MSG_SENDPAGE_NOTLAST)
 		flags |= MSG_MORE;
 
+	mutex_lock(&tls_ctx->tx_lock);
 	lock_sock(sk);
 
 	if (flags & MSG_OOB) {
@@ -568,6 +573,7 @@ int tls_device_sendpage(struct sock *sk, struct page *page,
 
 out:
 	release_sock(sk);
+	mutex_unlock(&tls_ctx->tx_lock);
 	return rc;
 }
 
@@ -623,9 +629,11 @@ static int tls_device_push_pending_record(struct sock *sk, int flags)
 
 void tls_device_write_space(struct sock *sk, struct tls_context *ctx)
 {
-	if (!sk->sk_write_pending && tls_is_partially_sent_record(ctx)) {
+	if (tls_is_partially_sent_record(ctx)) {
 		gfp_t sk_allocation = sk->sk_allocation;
 
+		WARN_ON_ONCE(sk->sk_write_pending);
+
 		sk->sk_allocation = GFP_ATOMIC;
 		tls_push_partial_record(sk, ctx,
 					MSG_DONTWAIT | MSG_NOSIGNAL |

net/tls/tls_main.c

@@ -267,6 +267,7 @@ void tls_ctx_free(struct sock *sk, struct tls_context *ctx)
 
 	memzero_explicit(&ctx->crypto_send, sizeof(ctx->crypto_send));
 	memzero_explicit(&ctx->crypto_recv, sizeof(ctx->crypto_recv));
+	mutex_destroy(&ctx->tx_lock);
 
 	if (sk)
 		kfree_rcu(ctx, rcu);
@@ -612,6 +613,7 @@ static struct tls_context *create_ctx(struct sock *sk)
 	if (!ctx)
 		return NULL;
 
+	mutex_init(&ctx->tx_lock);
 	rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
 	ctx->sk_proto = sk->sk_prot;
 	return ctx;

net/tls/tls_sw.c

@@ -897,15 +897,9 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 	if (msg->msg_flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL))
 		return -ENOTSUPP;
 
+	mutex_lock(&tls_ctx->tx_lock);
 	lock_sock(sk);
 
-	/* Wait till there is any pending write on socket */
-	if (unlikely(sk->sk_write_pending)) {
-		ret = wait_on_pending_writer(sk, &timeo);
-		if (unlikely(ret))
-			goto send_end;
-	}
-
 	if (unlikely(msg->msg_controllen)) {
 		ret = tls_proccess_cmsg(sk, msg, &record_type);
 		if (ret) {
@@ -1091,6 +1085,7 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 	ret = sk_stream_error(sk, msg->msg_flags, ret);
 
 	release_sock(sk);
+	mutex_unlock(&tls_ctx->tx_lock);
 	return copied ? copied : ret;
 }
 
@@ -1114,13 +1109,6 @@ static int tls_sw_do_sendpage(struct sock *sk, struct page *page,
 	eor = !(flags & (MSG_MORE | MSG_SENDPAGE_NOTLAST));
 	sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 
-	/* Wait till there is any pending write on socket */
-	if (unlikely(sk->sk_write_pending)) {
-		ret = wait_on_pending_writer(sk, &timeo);
-		if (unlikely(ret))
-			goto sendpage_end;
-	}
-
 	/* Call the sk_stream functions to manage the sndbuf mem. */
 	while (size > 0) {
 		size_t copy, required_size;
@@ -1219,15 +1207,18 @@ static int tls_sw_do_sendpage(struct sock *sk, struct page *page,
 int tls_sw_sendpage(struct sock *sk, struct page *page,
 		    int offset, size_t size, int flags)
 {
+	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	int ret;
 
 	if (flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL |
 		      MSG_SENDPAGE_NOTLAST | MSG_SENDPAGE_NOPOLICY))
 		return -ENOTSUPP;
 
+	mutex_lock(&tls_ctx->tx_lock);
 	lock_sock(sk);
 	ret = tls_sw_do_sendpage(sk, page, offset, size, flags);
 	release_sock(sk);
+	mutex_unlock(&tls_ctx->tx_lock);
 	return ret;
 }
 
@@ -2170,22 +2161,21 @@ static void tx_work_handler(struct work_struct *work)
 
 	if (!test_and_clear_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask))
 		return;
+	mutex_lock(&tls_ctx->tx_lock);
 	lock_sock(sk);
 	tls_tx_records(sk, -1);
 	release_sock(sk);
+	mutex_unlock(&tls_ctx->tx_lock);
 }
 
 void tls_sw_write_space(struct sock *sk, struct tls_context *ctx)
 {
 	struct tls_sw_context_tx *tx_ctx = tls_sw_ctx_tx(ctx);
 
 	/* Schedule the transmission if tx list is ready */
-	if (is_tx_ready(tx_ctx) && !sk->sk_write_pending) {
-		/* Schedule the transmission */
-		if (!test_and_set_bit(BIT_TX_SCHEDULED,
-				      &tx_ctx->tx_bitmask))
-			schedule_delayed_work(&tx_ctx->tx_work.work, 0);
-	}
+	if (is_tx_ready(tx_ctx) &&
+	    !test_and_set_bit(BIT_TX_SCHEDULED, &tx_ctx->tx_bitmask))
+		schedule_delayed_work(&tx_ctx->tx_work.work, 0);
 }
 
 void tls_sw_strparser_arm(struct sock *sk, struct tls_context *tls_ctx)

tools/testing/selftests/net/tls.c

@@ -898,6 +898,114 @@ TEST_F(tls, nonblocking)
 	}
 }
 
+static void
+test_mutliproc(struct __test_metadata *_metadata, struct _test_data_tls *self,
+	       bool sendpg, unsigned int n_readers, unsigned int n_writers)
+{
+	const unsigned int n_children = n_readers + n_writers;
+	const size_t data = 6 * 1000 * 1000;
+	const size_t file_sz = data / 100;
+	size_t read_bias, write_bias;
+	int i, fd, child_id;
+	char buf[file_sz];
+	pid_t pid;
+
+	/* Only allow multiples for simplicity */
+	ASSERT_EQ(!(n_readers % n_writers) || !(n_writers % n_readers), true);
+	read_bias = n_writers / n_readers ?: 1;
+	write_bias = n_readers / n_writers ?: 1;
+
+	/* prep a file to send */
+	fd = open("/tmp/", O_TMPFILE | O_RDWR, 0600);
+	ASSERT_GE(fd, 0);
+
+	memset(buf, 0xac, file_sz);
+	ASSERT_EQ(write(fd, buf, file_sz), file_sz);
+
+	/* spawn children */
+	for (child_id = 0; child_id < n_children; child_id++) {
+		pid = fork();
+		ASSERT_NE(pid, -1);
+		if (!pid)
+			break;
+	}
+
+	/* parent waits for all children */
+	if (pid) {
+		for (i = 0; i < n_children; i++) {
+			int status;
+
+			wait(&status);
+			EXPECT_EQ(status, 0);
+		}
+
+		return;
+	}
+
+	/* Split threads for reading and writing */
+	if (child_id < n_readers) {
+		size_t left = data * read_bias;
+		char rb[8001];
+
+		while (left) {
+			int res;
+
+			res = recv(self->cfd, rb,
+				   left > sizeof(rb) ? sizeof(rb) : left, 0);
+
+			EXPECT_GE(res, 0);
+			left -= res;
+		}
+	} else {
+		size_t left = data * write_bias;
+
+		while (left) {
+			int res;
+
+			ASSERT_EQ(lseek(fd, 0, SEEK_SET), 0);
+			if (sendpg)
+				res = sendfile(self->fd, fd, NULL,
+					       left > file_sz ? file_sz : left);
+			else
+				res = send(self->fd, buf,
+					   left > file_sz ? file_sz : left, 0);
+
+			EXPECT_GE(res, 0);
+			left -= res;
+		}
+	}
+}
+
+TEST_F(tls, mutliproc_even)
+{
+	test_mutliproc(_metadata, self, false, 6, 6);
+}
+
+TEST_F(tls, mutliproc_readers)
+{
+	test_mutliproc(_metadata, self, false, 4, 12);
+}
+
+TEST_F(tls, mutliproc_writers)
+{
+	test_mutliproc(_metadata, self, false, 10, 2);
+}
+
+TEST_F(tls, mutliproc_sendpage_even)
+{
+	test_mutliproc(_metadata, self, true, 6, 6);
+}
+
+TEST_F(tls, mutliproc_sendpage_readers)
+{
+	test_mutliproc(_metadata, self, true, 4, 12);
+}
+
+TEST_F(tls, mutliproc_sendpage_writers)
+{
+	test_mutliproc(_metadata, self, true, 10, 2);
+}
+
 TEST_F(tls, control_msg)
 {
 	if (self->notls)