Re: [PATCH 06/12] target/pr: Convert se_dev_entry to kref for RCU

From: Christoph Hellwig
Date: Wed May 13 2015 - 01:59:51 EST


On Tue, May 12, 2015 at 09:25:30AM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
>
> This patch converts se_dev_entry->pr_ref_count access to use modern
> struct kref counting.
>
> It updates core_enable_device_list_for_node() to kref_init() when se_dev_entry
> is being enabled, and updates core_disable_device_list_for_node() to kref_put()
> and blocks on ->pr_comp waiting for outstanding PR references to drop.
>
> Also, go ahead and convert core_get_se_deve_from_rtpi() code to use pr_kref
> for RELATIVE TARGET PORT IDENTIFIER lookup.

This seems to be two very different things. Once a fix up of the
->se_deve access in the PR code, and second changing the way the references
work.

The kref change looks fine to me as a standalone patch.

The RCU lookup changes really need to be squashed into the others,
for one thing before this patch the PR code still tries to use
->device_list which isn't even maintained any more.

It might be a good idea to grab these three patches from my older series
and add them before your actual RCU changes to simplify the PR code
in preparation of the RCU changes:

http://git.infradead.org/users/hch/scsi.git/commitdiff/e9a71bda1a120e0488c5c4e4b2f17f14333e2dc6
http://git.infradead.org/users/hch/scsi.git/commitdiff/6372d9f62c83acb30d051387c40deb4dbdcaa376
http://git.infradead.org/users/hch/scsi.git/commitdiff/1c52408094cb831ee3c791b71ef631b9c5609d35

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