MINOR: quic: strengthen qc_release_frm()

quic_frame is the type used to represent frames emitted in a QUIC Tx
packet. Each frame is attached to a packet, and can also be linked to
other frames from the the same packet, or duplicated frames for
retransmission. As such, quic_frame free operation is a tedious process.

qc_release_frm() has been implemented to ensure quic_frame is always
properly freed after detaching from all its list attach point. One
particular point is to ensure that when a frame is released, the frame
origin and all origin copies, including the current <frm> are flagged as
acked and detached from the reflist. Add a BUG_ON() to ensure this loop
is properly conducted when dealing with the current <frm> instance.

diff --git a/src/quic_frame.c b/src/quic_frame.c
index 6c459353c86fc56e504958b8fd90367b5c59b67b..9599b80c2e72ebb8e52454027fd71ab709f091bf 100644 (file)
--- a/src/quic_frame.c
+++ b/src/quic_frame.c
@@ -1242,6 +1242,12 @@ void qc_release_frm(struct quic_conn *qc, struct quic_frame *frm)
        uint64_t pn;
        struct quic_frame *origin, *f, *tmp;
 
+       /* <frm> will be detached from its Tx packet via origin->reflist loop
+        * implemented below. It is thus expected that its pkt field is not
+        * NULL or else it may free the frame too soon.
+        */
+       BUG_ON(!frm->pkt);
+
        TRACE_ENTER(QUIC_EV_CONN_PRSAFRM, qc, frm);
 
        /* Identify this frame: a frame copy or one of its copies */