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    Subject[PATCH 3.13 132/149] SCSI: isci: correct erroneous for_each_isci_host macro
    Date
    3.13-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Lukasz Dorau <lukasz.dorau@intel.com>

    commit c59053a23d586675c25d789a7494adfdc02fba57 upstream.

    In the first place, the loop 'for' in the macro 'for_each_isci_host'
    (drivers/scsi/isci/host.h:314) is incorrect, because it accesses
    the 3rd element of 2 element array. After the 2nd iteration it executes
    the instruction:
    ihost = to_pci_info(pdev)->hosts[2]
    (while the size of the 'hosts' array equals 2) and reads an
    out of range element.

    In the second place, this loop is incorrectly optimized by GCC v4.8
    (see http://marc.info/?l=linux-kernel&m=138998871911336&w=2).
    As a result, on platforms with two SCU controllers,
    the loop is executed more times than it can be (for i=0,1 and 2).
    It causes kernel panic during entering the S3 state
    and the following oops after 'rmmod isci':

    BUG: unable to handle kernel NULL pointer dereference at (null)
    IP: [<ffffffff8131360b>] __list_add+0x1b/0xc0
    Oops: 0000 [#1] SMP
    RIP: 0010:[<ffffffff8131360b>] [<ffffffff8131360b>] __list_add+0x1b/0xc0
    Call Trace:
    [<ffffffff81661b84>] __mutex_lock_slowpath+0x114/0x1b0
    [<ffffffff81661c3f>] mutex_lock+0x1f/0x30
    [<ffffffffa03e97cb>] sas_disable_events+0x1b/0x50 [libsas]
    [<ffffffffa03e9818>] sas_unregister_ha+0x18/0x60 [libsas]
    [<ffffffffa040316e>] isci_unregister+0x1e/0x40 [isci]
    [<ffffffffa0403efd>] isci_pci_remove+0x5d/0x100 [isci]
    [<ffffffff813391cb>] pci_device_remove+0x3b/0xb0
    [<ffffffff813fbf7f>] __device_release_driver+0x7f/0xf0
    [<ffffffff813fc8f8>] driver_detach+0xa8/0xb0
    [<ffffffff813fbb8b>] bus_remove_driver+0x9b/0x120
    [<ffffffff813fcf2c>] driver_unregister+0x2c/0x50
    [<ffffffff813381f3>] pci_unregister_driver+0x23/0x80
    [<ffffffffa04152f8>] isci_exit+0x10/0x1e [isci]
    [<ffffffff810d199b>] SyS_delete_module+0x16b/0x2d0
    [<ffffffff81012a21>] ? do_notify_resume+0x61/0xa0
    [<ffffffff8166ce29>] system_call_fastpath+0x16/0x1b

    The loop has been corrected.
    This patch fixes kernel panic during entering the S3 state
    and the above oops.

    Signed-off-by: Lukasz Dorau <lukasz.dorau@intel.com>
    Reviewed-by: Maciej Patelczyk <maciej.patelczyk@intel.com>
    Tested-by: Lukasz Dorau <lukasz.dorau@intel.com>
    Signed-off-by: Dan Williams <dan.j.williams@intel.com>
    Signed-off-by: James Bottomley <JBottomley@Parallels.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/scsi/isci/host.h | 5 ++---
    1 file changed, 2 insertions(+), 3 deletions(-)

    --- a/drivers/scsi/isci/host.h
    +++ b/drivers/scsi/isci/host.h
    @@ -311,9 +311,8 @@ static inline struct Scsi_Host *to_shost
    }

    #define for_each_isci_host(id, ihost, pdev) \
    - for (id = 0, ihost = to_pci_info(pdev)->hosts[id]; \
    - id < ARRAY_SIZE(to_pci_info(pdev)->hosts) && ihost; \
    - ihost = to_pci_info(pdev)->hosts[++id])
    + for (id = 0; id < SCI_MAX_CONTROLLERS && \
    + (ihost = to_pci_info(pdev)->hosts[id]); id++)

    static inline void wait_for_start(struct isci_host *ihost)
    {



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