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This commit is contained in:
J. Nick Koston
2026-02-24 08:42:23 -06:00
parent 8d997c247e
commit 36eb31e8ee
1 changed files with 7 additions and 5 deletions
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12
esphome/core/lwip_fast_select.c
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@@ -41,12 +41,14 @@
// The TCP/IP thread does NOT call free_socket(). On link loss, RST, or timeout
// it frees the TCP PCB and signals the netconn (rcvevent++ to indicate EOF), but
// the netconn and lwip_sock slot remain allocated until the application calls
// lwip_close(). ESPHome only calls lwip_close() from the main loop, after
// unregister_socket_fd() has already removed the fd from the monitored set.
// lwip_close(). ESPHome removes the fd from the monitored set before calling
// lwip_close().
//
// Therefore lwip_socket_dbg_get_socket(fd) plus a volatile read of rcvevent is
// safe as long as the application is single-writer for close — which ESPHome
// guarantees by design (all socket create/read/close happens on the main loop).
// Therefore lwip_socket_dbg_get_socket(fd) plus a volatile read of rcvevent
// (to prevent compiler reordering or caching) is safe as long as the application
// is single-writer for close. ESPHome guarantees this by design: all socket
// create/read/close happens on the main loop. fd numbers are not reused while
// the slot remains allocated, and the slot remains allocated until lwip_close().
//
// LwIP source references for slot lifetime:
// sockets.c (same commit as above):