tls: fix lockless read of strp->msg_ready in ->poll

tls_sk_poll is called without locking the socket, and needs to read
strp->msg_ready (via tls_strp_msg_ready). Convert msg_ready to a bool
and use READ_ONCE/WRITE_ONCE where needed. The remaining reads are
only performed when the socket is locked.

Fixes: 121dca784fc0 ("tls: suppress wakeups unless we have a full record")
Signed-off-by: Sabrina Dubroca <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

include/net/tls.h

···
 	u32 stopped : 1;
 	u32 copy_mode : 1;
 	u32 mixed_decrypted : 1;
-	u32 msg_ready : 1;
+
+	bool msg_ready;
 
 	struct strp_msg stm;
 

net/tls/tls.h

···
 
 static inline bool tls_strp_msg_ready(struct tls_sw_context_rx *ctx)
 {
-	return ctx->strp.msg_ready;
+	return READ_ONCE(ctx->strp.msg_ready);
 }
 
 static inline bool tls_strp_msg_mixed_decrypted(struct tls_sw_context_rx *ctx)

net/tls/tls_strp.c

···
 	if (strp->stm.full_len && strp->stm.full_len == skb->len) {
 		desc->count = 0;
 
-		strp->msg_ready = 1;
+		WRITE_ONCE(strp->msg_ready, 1);
 		tls_rx_msg_ready(strp);
 	}
 
···
 	if (!tls_strp_check_queue_ok(strp))
 		return tls_strp_read_copy(strp, false);
 
-	strp->msg_ready = 1;
+	WRITE_ONCE(strp->msg_ready, 1);
 	tls_rx_msg_ready(strp);
 
 	return 0;
···
 	else
 		tls_strp_flush_anchor_copy(strp);
 
-	strp->msg_ready = 0;
+	WRITE_ONCE(strp->msg_ready, 0);
 	memset(&strp->stm, 0, sizeof(strp->stm));
 
 	tls_strp_check_rcv(strp);