Re: [PATCH 0/2] eal: notify secondaries on primary exit

[Thomas Monjalon <thomas@monjalon.net>]

18/06/2026 18:09, Stephen Hemminger:
> On Thu,  7 May 2026 13:58:35 -0700
> Stephen Hemminger <stephen@networkplumber.org> wrote:
> 
> > Bugzilla 1942: when a primary process exits cleanly, secondary
> > processes other than testpmd do not get notified.  The notification
> > mechanism added in 25.11 was placed in testpmd and used
> > rte_mp_request_sync() with a testpmd-specific action name, so any
> > non-testpmd secondary (dpdk-dumpcap, dpdk-pdump, dpdk-procinfo, or
> > out-of-tree consumers) would log "Cannot find action: mp_testpmd"
> > and the primary would block on the 5 second request timeout.
> > 
> > Putting application-specific IPC actions on a broadcast request path
> > is the wrong layer.  Notification of primary exit is something every
> > secondary needs and should come from EAL, not from each application.
> > 
> > Patch 1 reverts the testpmd-side mechanism (commit f96273c8e9d3).
> > The secondary-side primary alive monitor (enable_primary_monitor)
> > is preserved and continues to handle detection of primary exit via
> > the existing alarm-based polling of rte_eal_primary_proc_alive().
> > 
> > Patch 2 adds a generic EAL-level notification.  On primary cleanup,
> > rte_mp_channel_cleanup() broadcasts an MP_REQ_QUIT message to all
> > known secondaries via rte_mp_sendmsg().  Secondaries register an
> > internal action handler that tears down their own MP channel on
> > receipt.  No new public API; no application changes required for
> > any secondary, in-tree or out.
> > 
> > This is the minimum fix suitable for backport to 25.11 stable.
> > It addresses the clean exit case.  The crash case (primary killed
> > or signaled) continues to be handled by the existing
> > rte_eal_primary_proc_alive() polling on the secondary side, which
> > detects the primary's release of the config file lock.
> > 
> > A more complete solution using a connected socket type (SOCK_SEQPACKET)
> > is planned since that can handle both planned and forced exiting
> > of the primary.
> > 
> > Tested with testpmd (primary) and dpdk-dumpcap, dpdk-pdump,
> > dpdk-procinfo (secondaries).
> > 
> > 
> > Stephen Hemminger (2):
> >   Revert "app/testpmd: stop forwarding in secondary process"
> >   eal: notify secondary on primary exit
> > 
> >  app/test-pmd/testpmd.c           | 103 ++-----------------------------
> >  lib/eal/common/eal_common_proc.c |  51 ++++++++++++++-
> >  2 files changed, 53 insertions(+), 101 deletions(-)
> > 
> 
> This is a real bug fix. Even if AI is being overly wordy in describing
> it; what it does is move the notification from being testpmd -> testpmd only
> to a more general primary -> secondary mechanism.
> 
> Without it can demonstrate the bug rather trivially with packet
> capture tools (pdump or dumpcap)
> 
> Could this get reviewed?

Anatoly reviewed.
Applied, thanks.