810f2b5030
Zero can be confused for a potentially valid value. For example, if I load and unload sbp driver I get a lot of messages like the following: fw_tl_free: the xfer is not in the queue (tlabel=0, flag=0x0) send: dst=0x00 tl=0x00 rt=0 tcode=0x0 pri=0x0 src=0x000 recv: dst=0x01 tl=0x21 rt=1 tcode=0x1 pri=0x0 src=0xffc0 KDB: stack backtrace: db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe04464407e0 fw_tl_free() at fw_tl_free+0x18d/frame 0xfffffe0446440820 fw_xfer_unload() at fw_xfer_unload+0xca/frame 0xfffffe0446440840 fw_xferlist_remove() at fw_xferlist_remove+0x2f/frame 0xfffffe0446440870 sbp_detach() at sbp_detach+0x1e0/frame 0xfffffe04464408e0 device_detach() at device_detach+0x80/frame 0xfffffe0446440900 devclass_driver_deleted() at devclass_driver_deleted+0x6a/frame 0xfffffe0446440940 devclass_delete_driver() at devclass_delete_driver+0x7d/frame 0xfffffe0446440980 driver_module_handler() at driver_module_handler+0xff/frame 0xfffffe04464409d0 module_unload() at module_unload+0x32/frame 0xfffffe04464409f0 linker_file_unload() at linker_file_unload+0x24b/frame 0xfffffe0446440a40 kern_kldunload() at kern_kldunload+0xbc/frame 0xfffffe0446440a70 amd64_syscall() at amd64_syscall+0x314/frame 0xfffffe0446440bf0 Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe0446440bf0 MFC after: 2 weeks
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