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From: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: target-devel <target-devel@vger.kernel.org>,
	linux-scsi <linux-scsi@vger.kernel.org>,
	lkml <linux-kernel@vger.kernel.org>,
	Rob Millner <rlm@daterainc.com>
Subject: Re: [PATCH 4/5] target: Fix multi-session dynamic se_node_acl double free OOPs
Date: Wed, 08 Feb 2017 08:14:57 -0800	[thread overview]
Message-ID: <1486570497.7066.6.camel@haakon3.risingtidesystems.com> (raw)
In-Reply-To: <1486525612.13263.18.camel@haakon3.risingtidesystems.com>

On Tue, 2017-02-07 at 19:46 -0800, Nicholas A. Bellinger wrote:
> On Tue, 2017-02-07 at 15:12 -0800, Christoph Hellwig wrote:
> > And the real patch after compile fixing it is here of course:
> > 
> 
> Getting rid of the extra se_node_acl->acl_free_comp seems to make sense
> here..
> 
> The only potential issue is if returning from configfs syscall
> rmdir /sys/kernel/config/target/$FABRIC/$WWN/$TPGT/acls/$INITIATOR/
> before se_node_acl memory is released has implications when the
> underlying ../$WWN/$TPGT/ is removed immediately after.
> 
> In any event, I'll verify this patch with the original test case and use
> it instead if everything looks OK.

Ok, I remember why se_node_acl->acl_free_comp is needed now..

The issue is when se_node_acl is being explicitly removed from configfs
while se_sessions associated with se_node_acl are still active.

The se_node_acl->acl_group configfs_group_operations->drop_item()
callback must block until all associated se_sessions have done their
target_put_nacl() and completed se_node_acl->acl_free_comp, otherwise
there is nothing preventing parent config_groups of se_node_acl from
being removed while the se_sessions are still active.

That said, dropping the unnecessary list_del_init() usage, but otherwise
keeping the patch as-is.

  reply	other threads:[~2017-02-08 16:15 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-07 13:17 [PATCH 0/5] target: Miscellaneous bug-fixes for >= v4.10 Nicholas A. Bellinger
2017-02-07 13:17 ` [PATCH 1/5] target: Don't BUG_ON during NodeACL dynamic -> explicit conversion Nicholas A. Bellinger
2017-02-07 22:44   ` Christoph Hellwig
2017-02-08 16:16     ` Nicholas A. Bellinger
2017-02-07 13:17 ` [PATCH 2/5] target: Use correct SCSI status during EXTENDED_COPY exception Nicholas A. Bellinger
2017-02-07 22:39   ` Christoph Hellwig
2017-02-07 13:17 ` [PATCH 3/5] target: Fix early transport_generic_handle_tmr abort scenario Nicholas A. Bellinger
2017-02-07 22:45   ` Christoph Hellwig
2017-02-07 13:17 ` [PATCH 4/5] target: Fix multi-session dynamic se_node_acl double free OOPs Nicholas A. Bellinger
2017-02-07 23:07   ` Christoph Hellwig
2017-02-07 23:12     ` Christoph Hellwig
2017-02-08  3:46       ` Nicholas A. Bellinger
2017-02-08 16:14         ` Nicholas A. Bellinger [this message]
2017-02-07 13:17 ` [PATCH 5/5] target: Fix COMPARE_AND_WRITE ref leak for non GOOD status Nicholas A. Bellinger
2017-02-07 22:51   ` Christoph Hellwig

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