From: Oleg Nesterov <oleg@redhat.com>
To: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Milind Chabbi <chabbi.milind@gmail.com>,
lkml <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
David Ahern <dsahern@gmail.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Frederic Weisbecker <frederic@kernel.org>
Subject: Re: [PATCH 2/2] perf/hw_breakpoint: Modify breakpoint even if the new attr has disabled set
Date: Mon, 6 Aug 2018 15:07:31 +0200 [thread overview]
Message-ID: <20180806130730.GD7840@redhat.com> (raw)
In-Reply-To: <20180806124839.GC7840@redhat.com>
On 08/06, Oleg Nesterov wrote:
>
> But, with or without this fix, shouldn't we set .disabled = 1 if modify_() fails?
> IIUC this doesn't matter, bp->attr.disabled is not really used anyway, but looks a
> bit confusing.
I am looking at another caller perf_event_modify_breakpoint(). It too doesn't set
attr.disabled = 1 on failure, it does _perf_event_enable() instead so attr.disabled
should be correct.
But this looks wrong. If modify_user_hw_breakpoint_check() paths fails after
arch_validate_hwbkpt_settings() was called, then we can not simply restore
bp_addr/bp_type/bp_len and do _perf_event_enable(). We need another
modify_user_hw_breakpoint_check() or validate_hw_breakpoint().
Note that arch_validate_hwbkpt_settings() updates arch_hw_breakpoint according
to bp.attr, the restored bp->attr.bp_addr/bp_typebp_len have no effect if we
call _perf_event_enable() after the failure.
Or I am totally confused?
Oleg.
next prev parent reply other threads:[~2018-08-06 13:07 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-06 10:12 [PATCH 0/2] perf/hw_breakpoint: Fix breakpoint modify Jiri Olsa
2018-08-06 10:12 ` [PATCH 1/2] perf tests: Add breakpoint modify test Jiri Olsa
2018-08-06 10:12 ` [PATCH 2/2] perf/hw_breakpoint: Modify breakpoint even if the new attr has disabled set Jiri Olsa
2018-08-06 12:48 ` Oleg Nesterov
2018-08-06 13:07 ` Oleg Nesterov [this message]
2018-08-06 13:37 ` Jiri Olsa
2018-08-06 13:49 ` Oleg Nesterov
2018-08-06 14:21 ` Jiri Olsa
2018-08-06 13:23 ` Jiri Olsa
2018-08-06 13:46 ` Oleg Nesterov
2018-08-06 15:08 ` [PATCH 3/2] perf/hw_breakpoint: Remove superfluous bp->attr.disabled = 0 " Jiri Olsa
2018-08-06 16:34 ` Oleg Nesterov
2018-08-07 8:16 ` Jiri Olsa
2018-08-07 9:10 ` Oleg Nesterov
2018-08-07 14:39 ` Jiri Olsa
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:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180806130730.GD7840@redhat.com \
--to=oleg@redhat.com \
--cc=a.p.zijlstra@chello.nl \
--cc=acme@kernel.org \
--cc=alexander.shishkin@linux.intel.com \
--cc=chabbi.milind@gmail.com \
--cc=dsahern@gmail.com \
--cc=frederic@kernel.org \
--cc=jolsa@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=namhyung@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.