BUG/MEDIUM: quic: Missing TX buffer draining from qc_send_ppkts()

If the TX buffer (->tx.buf) attached to the connection is not drained, there
are chances that this will be detected by qc_txb_release() which triggers
a BUG_ON_HOT() when this is the case as follows

[00|quic|2|c_conn.c:3477] UDP port unreachable : qc@0x5584f18d6d50 pto_count=0 cwnd=6816 ppif=1046 pif=1046
[00|quic|5|ic_conn.c:749] qc_kill_conn(): entering : qc@0x5584f18d6d50
[00|quic|5|ic_conn.c:752] qc_kill_conn(): leaving : qc@0x5584f18d6d50
[00|quic|5|c_conn.c:3532] qc_send_ppkts(): leaving : qc@0x5584f18d6d50 pto_count=0 cwnd=6816 ppif=1046 pif=1046

FATAL: bug condition "buf && b_data(buf)" matched at src/quic_conn.c:3098

Consume the remaining data in the TX buffer calling b_del().

This bug arrived with this commit:
    a2c62c314 MINOR: quic: Kill the connections on ICMP (port unreachable) packet receipt

Takes also the opportunity of this patch to modify the comments for qc_send_ppkts()
which should have arrived with a2c62c314 commit.

Must be backported to 2.7 where this latter commit is supposed to be backported.
1 file changed