From b01f54a004729008c46d77cb95f74bb41395ff04 Mon Sep 17 00:00:00 2001
From: Egor <egor@patchysicp.xyz>
Date: Sun, 2 Mar 2025 22:26:20 +0200
Subject: [PATCH] netpoll: wait for uv_close before reusing polldata

---
 src/netpoll.cpp | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/src/netpoll.cpp b/src/netpoll.cpp
index e50ca78..545a969 100644
--- a/src/netpoll.cpp
+++ b/src/netpoll.cpp
@@ -227,14 +227,33 @@ struct polldata {
 	uv_poll_t uv;
 	int events, revents, fd;
 };
-static polldata uvpollbuf[NETPOLL_MAXFDS] = {};
 static polldata *uvpoll[NETPOLL_MAXFDS] = {};
 static uv_loop_t *uvloop = 0;
 static int lastptr = 0;
+namespace uvalloc {
+	static polldata uvpollbuf[NETPOLL_MAXFDS] = {};
+	static polldata *freelist = 0;
+	static polldata *get() {
+		polldata *p = freelist;
+		freelist = static_cast<polldata *>(p->uv.data);
+		if (!p) {
+			fprintf(stderr, "uvalloc::get: out of polldata!\n");
+			abort();
+		}
+		return p;
+	}
+	static void put(polldata *p) {
+		p->uv.data = freelist;
+		freelist = p;
+	}
+	static void init() {
+		for (int i = NETPOLL_MAXFDS-1; i >= 0; i--)
+			put(&uvpollbuf[i]);
+	}
+}
 void net_poll_init(void)
 {
-	for (int i = 0; i < NETPOLL_MAXFDS; i++)
-		uvpoll[i] = &uvpollbuf[i];
+	uvalloc::init();
 	uvloop = uv_default_loop();
 }
 void net_poll_fini(void)
@@ -247,7 +266,7 @@ void net_poll_fini(void)
 }
 static void net_poll_add_impl(int i)
 {
-	struct polldata *poll = uvpoll[nfds-1];
+	struct polldata *poll = uvalloc::get();
 	memmove(uvpoll+i+1, uvpoll+i, sizeof(uvpoll[0])*(nfds-1-i));
 	uvpoll[i] = poll;
 	poll->events = 0;
@@ -261,8 +280,9 @@ static void net_poll_del_impl(int i)
 {
 	struct polldata *poll = uvpoll[i];
 	memmove(uvpoll+i, uvpoll+i+1, sizeof(uvpoll[0])*(nfds-(i+1)));
-	uvpoll[nfds-1] = poll;
-	uv_close((uv_handle_t *)&poll->uv, 0);
+	uv_close((uv_handle_t *)&poll->uv, [](uv_handle_t *handle){
+		uvalloc::put(container_of(handle, struct polldata, uv));
+	});
 	if (lastptr > i)
 		lastptr--;
 }
-- 
2.56.0