From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Frank Ch. Eigler" Date: Thu, 06 Dec 2012 21:39:35 +0000 Subject: Re: Possible SCTP peer receive window bug Message-Id: <20121206213935.GB15562@redhat.com> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sctp@vger.kernel.org Hi - Jamie.Parsons (@UNKNOWN_DOMAIN :-() wrote: > [...] There is still a bug in the system tap script as the exit > value of functions is always returned as the same as the entry value > to functions. [...] This is an occasionally confusing aspect of systemtap .return probes. As per the stapprobes man page and elsewhere, most $context variables accessed from .return probes represent function *entry-time snapshots*. Try instead use of the @entry() construct, which makes explicit which values you wish to be entry-time evaluated, and which later. probe module("sctp").function("sctp_process_init").return { printf("sctp_process_init updates assoc %p peer rwnd to %d\n", @entry($asoc), @cast(@entry($asoc),"sctp_association")->peer->rwnd); /* evaluated at .return time: ^^^^^^^^^^^^ */ } (http://sourceware.org/PR14437 should make the @cast unnecessary eventually.) - FChE