On Tue, 17 Aug 2021 20:57:50 +0530 Jerin Jacob <jerinjac...@gmail.com> wrote:
> On Tue, Aug 17, 2021 at 8:39 PM Stephen Hemminger > <step...@networkplumber.org> wrote: > > > > On Tue, 17 Aug 2021 13:08:46 +0530 > > Jerin Jacob <jerinjac...@gmail.com> wrote: > > > > > On Tue, Aug 17, 2021 at 9:23 AM Stephen Hemminger > > > <step...@networkplumber.org> wrote: > > > > > > > > On Tue, 17 Aug 2021 08:57:18 +0530 > > > > <jer...@marvell.com> wrote: > > > > > > > > > From: Jerin Jacob <jer...@marvell.com> > > > > > > > > > > Introducing oops handling API with following specification > > > > > and enable stub implementation for Linux and FreeBSD. > > > > > > > > > > On rte_eal_init() invocation, the EAL library installs the > > > > > oops handler for the essential signals. > > > > > The rte_oops_signals_enabled() API provides the list > > > > > of signals the library installed by the EAL. > > > > > > > > This is a big change, and many applications already handle these > > > > signals themselves. Therefore adding this needs to be opt-in > > > > and not enabled by default. > > > > > > In order to avoid every application explicitly register this > > > sighandler and to cater to the > > > co-existing application-specific signal-hander usage. > > > The following design has been chosen. (It is mentioned in the commit log, > > > I will describe here for more clarity) > > > > > > Case 1: > > > a) The application installs the signal handler prior to rte_eal_init(). > > > b) Implementation stores the application-specific signal and replace a > > > signal handler as oops eal handler > > > c) when application/DPDK get the segfault, the default EAL oops > > > handler gets invoked > > > d) Then it dumps the EAL specific message, it calls the > > > application-specific signal handler > > > installed in step 1 by application. This avoids breaking any contract > > > with the application. > > > i.e Behavior is the same current EAL now. > > > That is the reason for not using SA_RESETHAND(which call SIG_DFL after > > > eal oops handler instead > > > application-specific handler) > > > > > > Case 2: > > > a) The application install the signal handler after rte_eal_init(), > > > b) EAL hander get replaced with application handle then the application > > > can call > > > rte_oops_decode() to decode. > > > > > > In order to cater the above use case, rte_oops_signals_enabled() and > > > rte_oops_decode() > > > provided. > > > > > > Here we are not breaking any contract with the application. > > > Do you have concerns about this design? > > > > In our application as a service it is important not to do any backtrace > > in production. We rely on other infrastructure to process coredumps. > > Other infrastructure will work. For example, If we are using standard coredump > using linux infra. In Current implementation, > - EAL handler dump the DPDK OOPS like kernel on stderr > - Implementation calls SIG_DFL in eal oops handler > - The above step creates the coredump or re-directs any other > infrastructure you are using for coredump. > > > > > This should be controlled enabled by a command line argument. > > If we allow other infrastructure coredump to work as-is, why > enable/disable required from eal? The addition of DPDK OOPS adds additional steps which make all faults be identified as the oops code.
