• Wei Fang's avatar
    scsi: fix race between simultaneous decrements of ->host_failed · 72d8c36e
    Wei Fang authored
    sas_ata_strategy_handler() adds the works of the ata error handler to
    system_unbound_wq. This workqueue asynchronously runs work items, so the
    ata error handler will be performed concurrently on different CPUs. In
    this case, ->host_failed will be decreased simultaneously in
    scsi_eh_finish_cmd() on different CPUs, and become abnormal.
    
    It will lead to permanently inequality between ->host_failed and
    ->host_busy, and scsi error handler thread won't start running. IO
    errors after that won't be handled.
    
    Since all scmds must have been handled in the strategy handler, just
    remove the decrement in scsi_eh_finish_cmd() and zero ->host_busy after
    the strategy handler to fix this race.
    
    Fixes: 50824d6c ("[SCSI] libsas: async ata-eh")
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarWei Fang <fangwei1@huawei.com>
    Reviewed-by: default avatarJames Bottomley <jejb@linux.vnet.ibm.com>
    Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
    72d8c36e
scsi_eh.txt 16.9 KB