From: "Morten Brørup" <mb@smartsharesystems.com>
To: "Stephen Hemminger" <stephen@networkplumber.org>
Cc: <keith.wiles@intel.com>, <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] net/tap: avoid using SIGIO
Date: Tue, 28 Jul 2020 12:48:09 +0200 [thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35C61170@smartserver.smartshare.dk> (raw)
In-Reply-To: <20200727124415.79e75f39@hermes.lan>
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Stephen Hemminger
> Sent: Monday, July 27, 2020 9:44 PM
>
> On Mon, 27 Jul 2020 15:19:32 +0200
> Morten Brørup <mb@smartsharesystems.com> wrote:
>
> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Stephen
> Hemminger
> > > Sent: Wednesday, July 15, 2020 1:58 AM
> > >
> > > SIGIO maybe used by application, instead choose another rt-signal.
> > > Linux allows any signal to be used for signal based IO.
> > > Search for an unused signal in the available rt-signal range.
> >
> > Just an observation. Feel free to ignore at your convenience:
> >
> > The problem is the same as for SIGIO if the application sets up its
> own signal handler after this, and uses some hardcoded rt-signal that
> happens to be the one found to be free.
> >
> > Unless the application doesn't use a hardcoded rt-signal, but also
> searches for an unused one.
> >
> > So perhaps the "search for unused rt-signal" should be exposed as a
> generic support function for the application (and this driver) to use.
>
> There is no safe way to use a signal deep inside DPDK in a driver.
>
> This is not the kind of thing that should be exposed to the
> application.
>
> The algorithm for finding an RT signal conforms to the recommended
> policy on the signal(7)
> manual page.
>
> programs should never refer to real-time signals using hard-
> coded numbers, but instead should always refer to real-time
> signals
> using the notation SIGRTMIN+n, and include suitable (run-time)
> checks
> that SIGRTMIN+n does not exceed SIGRTMAX.
>
> The application should be following the proscribed policy on the man
> page.
> If it doesn't it is broken.
Great. That fully addresses my concern.
Acked-by: Morten Brørup <mb@smartsharesystems.com>
next prev parent reply other threads:[~2020-07-28 10:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-22 1:01 [dpdk-dev] [RFC] " Stephen Hemminger
2020-07-14 23:58 ` [dpdk-dev] [PATCH] " Stephen Hemminger
2020-07-27 13:19 ` Morten Brørup
2020-07-27 19:44 ` Stephen Hemminger
2020-07-28 10:48 ` Morten Brørup [this message]
2020-08-17 15:26 ` Ferruh Yigit
2020-08-25 19:33 ` Ferruh Yigit
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