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    SubjectRe: [PATCH 01/12] target: Convert se_node_acl->device_list[] to RCU hlist
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    On Tue, 2015-05-12 at 13:58 -0700, Andy Grover wrote:
    > On 05/12/2015 02:25 AM, Nicholas A. Bellinger wrote:
    > > From: Nicholas Bellinger <nab@linux-iscsi.org>
    > >
    > > This patch converts se_node_acl->device_list[] table for mappedluns
    > > to modern RCU hlist_head usage in order to support an arbitrary number
    > > of node_acl lun mappings.
    > >
    > > This includes changes to core_[enable,disable]_device_list_for_node()
    > > rcu_assign_pointer() and invokes call_rcu() for releasing memory, along
    > > with a number of RCU read path conversions in target_core_device.c code.
    > >
    > > Required for subsequent conversion of transport_lookup_cmd() to lock-less
    > > RCU read path.
    > >
    > > Cc: Hannes Reinecke <hare@suse.de>
    > > Cc: Christoph Hellwig <hch@lst.de>
    > > Cc: Sagi Grimberg <sagig@mellanox.com>
    > > Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

    <SNIP>

    > > diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
    > > index 042a734..6fb38df 100644
    > > --- a/include/target/target_core_base.h
    > > +++ b/include/target/target_core_base.h
    > > @@ -584,10 +584,12 @@ struct se_node_acl {
    > > char acl_tag[MAX_ACL_TAG_SIZE];
    > > /* Used for PR SPEC_I_PT=1 and REGISTER_AND_MOVE */
    > > atomic_t acl_pr_ref_count;
    > > + struct hlist_head lun_entry_hlist;
    > > struct se_dev_entry **device_list;
    >
    > Very nice to see all this posted!
    >
    > Patch 6 is where device_list is finally removed. Suggest squashing 1-6,
    > maybe after review, I'm guessing they're not bisectable.
    >

    The series is bisectable. With patch #1 in place ->device_list[] is
    still kzalloc()'ed, but new RCU pointer assignments are made into
    lun_entry_hlist[].

    Squashing the RCU reader paths (#2-6) for merge is OK, but it's still
    nice to break up reader / updater changes into separate patches.

    --nab



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