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Because: 1. we have to submit another read URB is resp_count != 0 (call service_outstanding_interrupt), otherwise receiving gets stuck 2. we should not set WDM_READ, to not confuse userspace 3. we should not set res_length to 0, otherwise  we get stuck again (actually, should we clear the "if (!desc->reslength)" in wdm_read(), since that's is no longer possible anymore? Best regards, Robert Hodaszi