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    SubjectRe: [qla2xxx] INFO: possible irq lock inversion dependency detected
    On Thu, 4 Oct 2012, Srivatsa S. Bhat wrote:

    > With the mainline kernel (in the merge window) I am seeing the following lockdep
    > splat every time during boot.
    >
    > Regards,
    > Srivatsa S. Bhat
    >
    > ------------------------------------>
    >
    > [ 3.940316] SCSI subsystem initialized
    > [ 3.949021] Fusion MPT base driver 3.04.20
    > [ 3.953141] Copyright (c) 1999-2008 LSI Corporation
    > [ 3.955471] Fusion MPT SAS Host driver 3.04.20
    > [ 3.955850] mptbase: ioc0: Initiating bringup
    > [ 4.656179] ioc0: LSISAS1064E B3: Capabilities={Initiator}
    > [ 16.216323] scsi0 : ioc0: LSISAS1064E B3, FwRev=011e0000h, Ports=1, MaxQ=277, IRQ=28
    > [ 16.248414] mptsas: ioc0: attaching ssp device: fw_channel 0, fw_id 1, phy 0, sas_addr 0x5000c5001d7e18c9
    > [ 16.259708] scsi 0:0:0:0: Direct-Access IBM-ESXS ST9146803SS B536 PQ: 0 ANSI: 5
    > [ 16.271986] mptsas: ioc0: attaching sata device: fw_channel 0, fw_id 3, phy 1, sas_addr 0x677c605e9f919a95
    > [ 16.284288] scsi 0:0:1:0: Direct-Access ATA GBRLB031XVECCM 4.26 PQ: 0 ANSI: 5
    > [ 16.348106] qla2xxx [0000:00:00.0]-0005: : QLogic Fibre Channel HBA Driver: 8.04.00.03-k.
    > [ 16.356369] qla2xxx [0000:24:00.0]-001d: : Found an ISP2532 irq 32 iobase 0xffffc9001e0ba000.
    > [ 16.365364] qla2xxx 0000:24:00.0: irq 66 for MSI/MSI-X
    > [ 16.370527] qla2xxx 0000:24:00.0: irq 67 for MSI/MSI-X
    > [ 16.436226] scsi1 : qla2xxx
    > [ 17.280685] qla2xxx [0000:24:00.0]-505f:1: Link is operational (2 Gbps).
    > [ 17.780955]
    > [ 17.782450] =========================================================
    > [ 17.784924] [ INFO: possible irq lock inversion dependency detected ]
    > [ 17.784924] 3.6.0-0.0.0.28.36b5ec9-default #1 Not tainted
    > [ 17.784924] ---------------------------------------------------------
    > [ 17.784924] qla2xxx_1_dpc/368 just changed the state of lock:
    > [ 17.784924] (&(&ha->vport_slock)->rlock){+.....}, at: [<ffffffffa009b377>] qla2x00_configure_hba+0x197/0x3c0 [qla2xxx]
    > [ 17.784924] but this lock was taken by another, HARDIRQ-safe lock in the past:
    > [ 17.784924] (&(&ha->hardware_lock)->rlock){-.....}

    This seems to be real. You should be seeing that since 3.5-rc1 already
    though ... ?

    Does the patch below fix that?




    From: Jiri Kosina <jkosina@suse.cz>
    Subject: [PATCH] [SCSI] qla2xxx: fix potential deadlock on ha->hardware_lock

    Lockdep reports:

    === [ cut here ] ===
    =========================================================
    [ INFO: possible irq lock inversion dependency detected ]
    3.6.0-0.0.0.28.36b5ec9-default #1 Not tainted
    ---------------------------------------------------------
    qla2xxx_1_dpc/368 just changed the state of lock:
    (&(&ha->vport_slock)->rlock){+.....}, at: [<ffffffffa009b377>] qla2x00_configure_hba+0x197/0x3c0 [qla2xxx]
    but this lock was taken by another, HARDIRQ-safe lock in the past:
    (&(&ha->hardware_lock)->rlock){-.....}

    and interrupts could create inverse lock ordering between them.

    other info that might help us debug this:
    Possible interrupt unsafe locking scenario:

    CPU0 CPU1
    ---- ----
    lock(&(&ha->vport_slock)->rlock);
    local_irq_disable();
    lock(&(&ha->hardware_lock)->rlock);
    lock(&(&ha->vport_slock)->rlock);
    <Interrupt>
    lock(&(&ha->hardware_lock)->rlock);
    === [ cut here ] ===

    Fix the potential deadlock by disabling IRQs while holding ha->vport_slock.

    Reported-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
    Signed-off-by: Jiri Kosina <jkosina@suse.cz>
    ---
    drivers/scsi/qla2xxx/qla_init.c | 5 +++--
    1 files changed, 3 insertions(+), 2 deletions(-)

    diff --git a/drivers/scsi/qla2xxx/qla_init.c b/drivers/scsi/qla2xxx/qla_init.c
    index 799a58b..48fca47 100644
    --- a/drivers/scsi/qla2xxx/qla_init.c
    +++ b/drivers/scsi/qla2xxx/qla_init.c
    @@ -2080,6 +2080,7 @@ qla2x00_configure_hba(scsi_qla_host_t *vha)
    uint8_t domain;
    char connect_type[22];
    struct qla_hw_data *ha = vha->hw;
    + unsigned long flags;

    /* Get host addresses. */
    rval = qla2x00_get_adapter_id(vha,
    @@ -2154,9 +2155,9 @@ qla2x00_configure_hba(scsi_qla_host_t *vha)
    vha->d_id.b.area = area;
    vha->d_id.b.al_pa = al_pa;

    - spin_lock(&ha->vport_slock);
    + spin_lock_irqsave(&ha->vport_slock, flags);
    qlt_update_vp_map(vha, SET_AL_PA);
    - spin_unlock(&ha->vport_slock);
    + spin_unlock_irqrestore(&ha->vport_slock, flags);

    if (!vha->flags.init_done)
    ql_log(ql_log_info, vha, 0x2010,
    --
    Jiri Kosina
    SUSE Labs


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