• Konrad Rzeszutek Wilk's avatar
    xen/blkfront: Add WARN to deal with misbehaving backends. · 6878c32e
    Konrad Rzeszutek Wilk authored
    Part of the ring structure is the 'id' field which is under
    control of the frontend. The frontend stamps it with "some"
    value (this some in this implementation being a value less
    than BLK_RING_SIZE), and when it gets a response expects
    said value to be in the response structure. We have a check
    for the id field when spolling new requests but not when
    de-spolling responses.
    
    We also add an extra check in add_id_to_freelist to make
    sure that the 'struct request' was not NULL - as we cannot
    pass a NULL to __blk_end_request_all, otherwise that crashes
    (and all the operations that the response is dealing with
    end up with __blk_end_request_all).
    
    Lastly we also print the name of the operation that failed.
    
    [v1: s/BUG/WARN/ suggested by Stefano]
    [v2: Add extra check in add_id_to_freelist]
    [v3: Redid op_name per Jan's suggestion]
    [v4: add const * and add WARN on failure returns]
    Acked-by: default avatarJan Beulich <jbeulich@suse.com>
    Acked-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
    Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    6878c32e
xen-blkfront.c 38.4 KB