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authorJakub Kicinski <jakub.kicinski@netronome.com>2019-11-05 14:24:35 -0800
committerDavid S. Miller <davem@davemloft.net>2019-11-06 17:33:32 -0800
commit79ffe6087e9145d2377385cac48d0d6a6b4225a5 (patch)
tree7ad119676734db269b7ae127d3bf0908339306eb /net/tls/tls_sw.c
parent02b1fa07bb58f5d1f349b5b09eb936739a7b20fc (diff)
net/tls: add a TX lock
TLS TX needs to release and re-acquire the socket lock if send buffer fills up. TLS SW TX path currently depends on only allowing one thread to enter the function by the abuse of sk_write_pending. If another writer is already waiting for memory no new ones are allowed in. This has two problems: - writers don't wake other threads up when they leave the kernel; meaning that this scheme works for single extra thread (second application thread or delayed work) because memory becoming available will send a wake up request, but as Mallesham and Pooja report with larger number of threads it leads to threads being put to sleep indefinitely; - the delayed work does not get _scheduled_ but it may _run_ when other writers are present leading to crashes as writers don't expect state to change under their feet (same records get pushed and freed multiple times); it's hard to reliably bail from the work, however, because the mere presence of a writer does not guarantee that the writer will push pending records before exiting. Ensuring wakeups always happen will make the code basically open code a mutex. Just use a mutex. The TLS HW TX path does not have any locking (not even the sk_write_pending hack), yet it uses a per-socket sg_tx_data array to push records. Fixes: a42055e8d2c3 ("net/tls: Add support for async encryption of records for performance") Reported-by: Mallesham Jatharakonda <mallesh537@gmail.com> Reported-by: Pooja Trivedi <poojatrivedi@gmail.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Reviewed-by: Simon Horman <simon.horman@netronome.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tls/tls_sw.c')
-rw-r--r--net/tls/tls_sw.c21
1 files changed, 7 insertions, 14 deletions
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index e155b792df0b..446f23c1f3ce 100644
--- a/net/tls/tls_sw.c
+++ b/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 @@ send_end:
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 @@ sendpage_end:
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;
}
@@ -2170,9 +2161,11 @@ 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)