archive mirror
 help / color / mirror / Atom feed
From: Mathieu Desnoyers <>
To: Guo Ren <>
Cc: linux-kernel <>,
	Alexander Viro <>,
	Linus Torvalds <>,
Subject: Re: [RFC PATCH 2/2] Revert "csky: Add support for restartable sequence"
Date: Mon, 26 Jul 2021 12:28:20 -0400 (EDT)	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

----- On Jul 26, 2021, at 12:10 PM, Guo Ren wrote:

> Hi Mathieu,
> Sorry for forgetting to CC you in the last patch, and that patch has
> been merged into master which has the problem of syscall restart.
> I still want to keep rseq feature for csky, and implement the
> RSEQ_SKIP_FASTPATH for self-test, it that okay?

No, the RSEQ_SKIP_FASTPATH is the one special-case of test build which
skips building rseq critical sections entirely. This leaves out any
relevant testing of rseq per-se. With what we have in the upstream
selftests, I expect this test configuration to abort at runtime because
no slow-path fallbacks are available when the fastpath is disabled.

The asm glue to test rseq user-space really needs to be implemented
for any useful testing to be done here.

Unless that asm glue is contributed, none of the rseq logic is actually
tested on that architecture.

Considering the extremely-hard-to-debug nature of races with a broken
rseq kernel implementation, proper testing coverage is paramount, so I
still recommend the revert unless the selftests user-space asm glue is
contributed for C-Sky.



Mathieu Desnoyers
EfficiOS Inc.

      reply	other threads:[~2021-07-26 16:38 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-23 16:15 [RFC PATCH 1/2] Revert "csky: Fixup CONFIG_DEBUG_RSEQ" Mathieu Desnoyers
2021-07-23 16:16 ` [RFC PATCH 2/2] Revert "csky: Add support for restartable sequence" Mathieu Desnoyers
2021-07-26 16:10   ` Guo Ren
2021-07-26 16:28     ` Mathieu Desnoyers [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \
    --subject='Re: [RFC PATCH 2/2] Revert "csky: Add support for restartable sequence"' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).