• Wengang Wang's avatar
    rds: re-entry of rds_ib_xmit/rds_iw_xmit · d655a9fb
    Wengang Wang authored
    The BUG_ON at line 452/453 is triggered in function rds_send_xmit.
    
     441                         while (ret) {
     442                                 tmp = min_t(int, ret, sg->length -
     443                                                       conn->c_xmit_data_off);
     444                                 conn->c_xmit_data_off += tmp;
     445                                 ret -= tmp;
     446                                 if (conn->c_xmit_data_off == sg->length) {
     447                                         conn->c_xmit_data_off = 0;
     448                                         sg++;
     449                                         conn->c_xmit_sg++;
     450                                         if (ret != 0 && conn->c_xmit_sg == rm->data.op_nents)
     451                                                 printk(KERN_ERR "conn %p rm %p sg %p ret %d\n", conn, rm, sg, ret);
     452                                         BUG_ON(ret != 0 &&
     453                                                conn->c_xmit_sg == rm->data.op_nents);
     454                                 }
     455                         }
    
    it is complaining the total sent length is bigger that we want to send.
    
    rds_ib_xmit() is wrong for the second entry for the same rds_message returning
    wrong value.
    
    the sg and off passed by rds_send_xmit to rds_ib_xmit is based on
    scatterlist.offset/length, but the rds_ib_xmit action is based on
    scatterlist.dma_address/dma_length. in case dma_length is larger than length
    there is problem. for the 2nd and later entries of rds_ib_xmit for same
    rds_message, at least one of the following two is wrong:
    
    1) the scatterlist to start with,  the choosen one can far beyond the correct
       one.
    2) the offset to start with within the scatterlist.
    
    fix:
    add op_dmasg and op_dmaoff to rm_data_op structure indicating the scatterlist
    and offset within the it to start with for rds_ib_xmit respectively. op_dmasg
    and op_dmaoff are initialized to zero when doing dma mapping for the first see
    of the message and are changed when filling send slots.
    
    the same applies to rds_iw_xmit too.
    Signed-off-by: default avatarWengang Wang <wen.gang.wang@oracle.com>
    Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
    d655a9fb
iw_send.c 29.3 KB