mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Andi Kleen <ak@linux.intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: "Luck, Tony" <tony.luck@intel.com>,
	Jeremy Cline <jcline@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, linux-edac@vger.kernel.org,
	linux-kernel@vger.kernel.org, Laura Abbott <labbott@redhat.com>
Subject: Re: x86/mce: suspicious RCU usage in 4.13.4
Date: Wed, 11 Oct 2017 16:11:37 -0700	[thread overview]
Message-ID: <20171011231137.GI5109@tassilo.jf.intel.com> (raw)
In-Reply-To: <20171011115020.i4gkcy5pjifh2zsm@pd.tnic>

> -	next = mce_log_get_idx_check(mcelog.next);
> +	next = mcelog.next;
>  
>  	/* Only supports full reads right now */
>  	err = -EINVAL;
> @@ -281,8 +266,6 @@ static ssize_t mce_chrdev_read(struct file *filp, char __user *ubuf,
>  		next = cmpxchg(&mcelog.next, prev, 0);
>  	} while (next != prev);
>  
> -	synchronize_sched();

Sorry I take back what I wrote earlier. This RCU is actually still needed,
otherwise the reader could see partially written entries.

So rather have to keep that, and change the read code to run with rcu_read_lock()

-Andi

  parent reply	other threads:[~2017-10-11 23:11 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-10 19:00 Jeremy Cline
2017-10-10 19:44 ` Borislav Petkov
2017-10-10 20:08   ` Luck, Tony
2017-10-10 20:13     ` Andi Kleen
2017-10-11 11:50       ` Borislav Petkov
2017-10-11 21:34         ` Luck, Tony
2017-10-15  9:40           ` Borislav Petkov
2017-10-16 18:28             ` Luck, Tony
2017-11-01 14:56               ` Laura Abbott
2017-11-01 16:47                 ` Borislav Petkov
2017-11-01 20:07                   ` Luck, Tony
2017-11-01 20:28                   ` [tip:ras/urgent] x86/mcelog: Get rid of RCU remnants tip-bot for Borislav Petkov
2017-10-11 23:11         ` Andi Kleen [this message]
2017-10-12  9:02           ` x86/mce: suspicious RCU usage in 4.13.4 Borislav Petkov
2017-10-12 22:13             ` Andi Kleen

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=20171011231137.GI5109@tassilo.jf.intel.com \
    --to=ak@linux.intel.com \
    --cc=bp@alien8.de \
    --cc=hpa@zytor.com \
    --cc=jcline@redhat.com \
    --cc=labbott@redhat.com \
    --cc=linux-edac@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=tglx@linutronix.de \
    --cc=tony.luck@intel.com \
    --cc=x86@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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome