lkml.org 
[lkml]   [2015]   [Jul]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 1/2] mpt2sas: Refcount sas_device objects and fix unsafe list usage
    On 07/12/2015 12:24 AM, Calvin Owens wrote:
    > These objects can be referenced concurrently throughout the driver, we
    > need a way to make sure threads can't delete them out from under each
    > other. This patch adds the refcount, and refactors the code to use it.
    >
    > Additionally, we cannot iterate over the sas_device_list without
    > holding the lock, or we risk corrupting random memory if items are
    > added or deleted as we iterate. This patch refactors _scsih_probe_sas()
    > to use the sas_device_list in a safe way.
    >
    > Cc: Christoph Hellwig <hch@infradead.org>
    > Cc: Bart Van Assche <bart.vanassche@sandisk.com>
    > Signed-off-by: Calvin Owens <calvinowens@fb.com>
    > ---
    > drivers/scsi/mpt2sas/mpt2sas_base.h | 22 +-
    > drivers/scsi/mpt2sas/mpt2sas_scsih.c | 434 ++++++++++++++++++++-----------
    > drivers/scsi/mpt2sas/mpt2sas_transport.c | 12 +-
    > 3 files changed, 315 insertions(+), 153 deletions(-)

    [ ... snip ... ]

    > @@ -2078,7 +2150,7 @@ _scsih_slave_configure(struct scsi_device *sdev)
    > }
    >
    > spin_lock_irqsave(&ioc->sas_device_lock, flags);
    > - sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
    > + sas_device = __mpt2sas_get_sdev_by_addr(ioc,
    > sas_device_priv_data->sas_target->sas_address);
    > if (!sas_device) {
    > spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
    > @@ -2116,13 +2188,14 @@ _scsih_slave_configure(struct scsi_device *sdev)
    > if (!ssp_target)
    > _scsih_display_sata_capabilities(ioc, handle, sdev);
    >
    > -
    > _scsih_change_queue_depth(sdev, qdepth);
    >
    > if (ssp_target) {
    > sas_read_port_mode_page(sdev);
    > _scsih_enable_tlr(ioc, sdev);
    > }
    > +
    > + sas_device_put(sas_device);
    > return 0;
    > }

    Hi Calvin,

    Any reason why this sas_device_put is placed outside the sas_device
    lock? Most other instances in this patch were called just before unlocking.

    BTW I attempted testing, but needed to port to mpt3 and ended up with a
    driver that didn't boot :( Hopefully I can retry later this week, or
    find an older mpt2 box lying around.

    -- Joe


    \
     
     \ /
      Last update: 2015-07-13 17:21    [W:2.352 / U:0.140 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site