linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Michael Bringmann <mwb@linux.vnet.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	Rob Herring <robh@kernel.org>,
	Tyrel Datwyler <tyreld@linux.vnet.ibm.com>,
	"Juliet M. Kim" <minkim@linux.vnet.ibm.com>,
	Nathan Lynch <nathanl@linux.vnet.ibm.com>,
	Thomas Falcon <tlfalcon@linux.vnet.ibm.com>,
	Michael Bringmann <mwb@linux.vnet.ibm.com>
Subject: [PATCH] powerpc/pseries: Fix dn reference error in dlpar_cpu_remove_by_index
Date: Tue, 19 Feb 2019 09:46:42 -0600	[thread overview]
Message-ID: <cc20c5cc-cf8e-d125-cac9-5d1b938a1d86@linux.vnet.ibm.com> (raw)

powerpc/pseries: Fix dn reference error in dlpar_cpu_remove_by_index()

A reference to the device node of the CPU to be removed is released
upon successful removal of the associated CPU device.  If the call
to remove the CPU device fails, dlpar_cpu_remove_by_index() still
frees the reference and this leads to miscomparisons and/or
addressing errors later on.

This problem may be observed when trying to DLPAR 'hot-remove' a CPU
from a system that has only a single CPU.  The operation will fail
because there is no other CPU to which the kernel operations may be
migrated, but the refcount will still be decremented.

Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>


diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 97feb6e..9537bb9 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -635,7 +635,8 @@ static int dlpar_cpu_remove_by_index(u32 drc_index)
 	}
 
 	rc = dlpar_cpu_remove(dn, drc_index);
-	of_node_put(dn);
+	if (!rc)
+		of_node_put(dn);
 	return rc;
 }
 


             reply	other threads:[~2019-02-19 15:46 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-19 15:46 Michael Bringmann [this message]
2019-02-19 20:03 ` [PATCH] powerpc/pseries: Fix dn reference error in dlpar_cpu_remove_by_index Tyrel Datwyler
2019-02-20 20:18   ` Michael Bringmann

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=cc20c5cc-cf8e-d125-cac9-5d1b938a1d86@linux.vnet.ibm.com \
    --to=mwb@linux.vnet.ibm.com \
    --cc=benh@kernel.crashing.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=minkim@linux.vnet.ibm.com \
    --cc=mpe@ellerman.id.au \
    --cc=nathanl@linux.vnet.ibm.com \
    --cc=npiggin@gmail.com \
    --cc=paulus@samba.org \
    --cc=robh@kernel.org \
    --cc=tlfalcon@linux.vnet.ibm.com \
    --cc=tyreld@linux.vnet.ibm.com \
    /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;
as well as URLs for NNTP newsgroup(s).