From: "Mattias Rönnblom" <hofors@lysator.liu.se>
To: Stephen Hemminger <stephen@networkplumber.org>, dev@dpdk.org
Cc: anatoly.burakov@intel.com
Subject: Re: [PATCH] doc/eal: add signal safety warning
Date: Sat, 11 Jun 2022 18:50:06 +0200 [thread overview]
Message-ID: <2388f64e-6287-c930-7d2f-5644b855671b@lysator.liu.se> (raw)
In-Reply-To: <20220610152343.38455-1-stephen@networkplumber.org>
On 2022-06-10 17:23, Stephen Hemminger wrote:
> The DPDK is not designed to be used from a signal handler.
> Add a notice in the documentation describing this limitation,
> similar to Linux signal-safety manual page.
>
> Bugzilla ID: 1030
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
> doc/guides/prog_guide/env_abstraction_layer.rst | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/doc/guides/prog_guide/env_abstraction_layer.rst b/doc/guides/prog_guide/env_abstraction_layer.rst
> index 5f0748fba1c0..36ab4b5ba9b6 100644
> --- a/doc/guides/prog_guide/env_abstraction_layer.rst
> +++ b/doc/guides/prog_guide/env_abstraction_layer.rst
> @@ -732,6 +732,19 @@ controlled with tools like taskset (Linux) or cpuset (FreeBSD),
> - with affinity restricted to 2-3, the Control Threads will end up on
> CPU 2 (main lcore, which is the default when no CPU is available).
>
> +Signal Safety
> +~~~~~~~~~~~~~
> +
> +The DPDK functions in general can not be safely called from a signal handler.
> +Most functions are not async-signal-safe because they can acquire locks
> +and other resources that make them nonrentrant.
> +
> +To avoid problems with unsafe functions, can be avoided if required
> +signals are blocked and a mechanism such as signalfd (Linux) is used
> +to convert the asynchronous signals into messages that are processed
> +by a EAL thread.
> +
Should we instead actually try to figure out what part of the API is and
should remain async-signal-safe? And then say "nothing else is".
Without an exhaustive list, we will leave the user to guessing, or going
into the current implementation to find out if a particular function is
currently async-signal-safe. When that code changes in a future
supposed-to-be-backward-compatible DPDK release, the application will break.
> +
> .. _known_issue_label:
>
> Known Issues
next prev parent reply other threads:[~2022-06-11 16:50 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-10 15:23 Stephen Hemminger
2022-06-10 22:53 ` Tyler Retzlaff
2022-06-10 23:38 ` Stephen Hemminger
2022-06-10 23:42 ` Tyler Retzlaff
2022-06-11 1:37 ` fengchengwen
2022-06-11 16:50 ` Mattias Rönnblom [this message]
2022-07-05 20:44 ` [PATCH v2] " Stephen Hemminger
2022-07-11 21:15 ` Thomas Monjalon
2022-07-11 21:31 ` Stephen Hemminger
2022-10-21 19:58 ` Stephen Hemminger
2022-07-11 23:02 ` [PATCH v3] " Stephen Hemminger
2022-07-11 23:04 ` [PATCH v4] " Stephen Hemminger
2022-11-09 23:17 ` Stephen Hemminger
2022-11-15 16:21 ` David Marchand
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