lkml.org 
[lkml]   [2017]   [Jun]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patches in this message
    /
    From
    SubjectRe: [PATCH 1/3] target: Add support for TMR percpu reference counting
    Date
    Looks good.

    Regards,
    Quinn Tran

    -----Original Message-----
    From: Nicholas Bellinger <nab@linux-iscsi.org>
    Date: Saturday, June 3, 2017 at 3:10 PM
    To: target-devel <target-devel@vger.kernel.org>
    Cc: linux-scsi <linux-scsi@vger.kernel.org>, lkml <linux-kernel@vger.kernel.org>, Nicholas Bellinger <nab@linux-iscsi.org>, "Madhani, Himanshu" <Himanshu.Madhani@cavium.com>, "Tran, Quinn" <Quinn.Tran@cavium.com>, Mike Christie <mchristi@redhat.com>, Hannes Reinecke <hare@suse.com>, Christoph Hellwig <hch@lst.de>
    Subject: [PATCH 1/3] target: Add support for TMR percpu reference counting

    From: Nicholas Bellinger <nab@linux-iscsi.org>

    This patch introduces TMR percpu reference counting using
    se_lun->lun_ref in transport_lookup_tmr_lun(), following
    how existing non TMR per se_lun reference counting works
    within transport_lookup_cmd_lun().

    It also adds explicit transport_lun_remove_cmd() calls to
    drop the reference in the three tmr related locations that
    invoke transport_cmd_check_stop_to_fabric();

    - target_tmr_work() during normal ->queue_tm_rsp()
    - target_complete_tmr_failure() during error ->queue_tm_rsp()
    - transport_generic_handle_tmr() during early failure

    Also, note the exception paths in transport_generic_free_cmd()
    and transport_cmd_finish_abort() already check SCF_SE_LUN_CMD,
    and will invoke transport_lun_remove_cmd() when necessary.

    Cc: Himanshu Madhani <himanshu.madhani@cavium.com>
    Cc: Quinn Tran <quinn.tran@cavium.com>
    Cc: Mike Christie <mchristi@redhat.com>
    Cc: Hannes Reinecke <hare@suse.com>
    Cc: Christoph Hellwig <hch@lst.de>
    Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
    ---
    drivers/target/target_core_device.c | 14 ++++++++++----
    drivers/target/target_core_transport.c | 3 +++
    2 files changed, 13 insertions(+), 4 deletions(-)

    diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
    index 8f0e0e3..11c80c4 100644
    --- a/drivers/target/target_core_device.c
    +++ b/drivers/target/target_core_device.c
    @@ -168,11 +168,20 @@ int transport_lookup_tmr_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
    rcu_read_lock();
    deve = target_nacl_find_deve(nacl, unpacked_lun);
    if (deve) {
    - se_cmd->se_lun = rcu_dereference(deve->se_lun);
    se_lun = rcu_dereference(deve->se_lun);
    +
    + if (!percpu_ref_tryget_live(&se_lun->lun_ref)) {
    + se_lun = NULL;
    + goto out_unlock;
    + }
    +
    + se_cmd->se_lun = rcu_dereference(deve->se_lun);
    se_cmd->pr_res_key = deve->pr_res_key;
    se_cmd->orig_fe_lun = unpacked_lun;
    + se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
    + se_cmd->lun_ref_active = true;
    }
    +out_unlock:
    rcu_read_unlock();
    if (!se_lun) {
    @@ -182,9 +191,6 @@ int transport_lookup_tmr_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
    unpacked_lun);
    return -ENODEV;
    }
    - /*
    - * XXX: Add percpu se_lun->lun_ref reference count for TMR
    - */
    se_cmd->se_dev = rcu_dereference_raw(se_lun->lun_se_dev);
    se_tmr->tmr_dev = rcu_dereference_raw(se_lun->lun_se_dev);
    diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
    index f16a789..83bfc97 100644
    --- a/drivers/target/target_core_transport.c
    +++ b/drivers/target/target_core_transport.c
    @@ -1588,6 +1588,7 @@ static void target_complete_tmr_failure(struct work_struct *work)
    se_cmd->se_tmr_req->response = TMR_LUN_DOES_NOT_EXIST;
    se_cmd->se_tfo->queue_tm_rsp(se_cmd);
    + transport_lun_remove_cmd(se_cmd);
    transport_cmd_check_stop_to_fabric(se_cmd);
    }
    @@ -3199,6 +3200,7 @@ static void target_tmr_work(struct work_struct *work)
    cmd->se_tfo->queue_tm_rsp(cmd);
    check_stop:
    + transport_lun_remove_cmd(cmd);
    transport_cmd_check_stop_to_fabric(cmd);
    }
    @@ -3221,6 +3223,7 @@ int transport_generic_handle_tmr(
    pr_warn_ratelimited("handle_tmr caught CMD_T_ABORTED TMR %d"
    "ref_tag: %llu tag: %llu\n", cmd->se_tmr_req->function,
    cmd->se_tmr_req->ref_task_tag, cmd->tag);
    + transport_lun_remove_cmd(cmd);
    transport_cmd_check_stop_to_fabric(cmd);
    return 0;
    }
    --
    1.9.1


    \
     
     \ /
      Last update: 2017-06-12 00:58    [W:4.122 / U:0.052 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site