> No, this is a fundamental problem. You don't > refcount > a pointer, you refcount a data structure. > But this is insufficient. We need to make > sure the pointer points to valid memory.
I understand. But a typical definition of ref-count requires the count in the data structure to be equal to the number of outstanding pointers to this data structure. Every time we create a new pointer, the ref count should be incremented. When pointer is erased, count is decremented. This is what I meant as "ref counting a pointer". If we follow this rule, then each pointer will always point to a valid memory. So, if we apply ref counting rules consistently, then each pointer in serial_table should be ref counted. This will completely break the current code, which erases serial_table from destroy_serial, which is called only when the ref count goes to 0, which will never happen if serial_table is ref counted. However, this can be fixed if usb_serial_disconnect will erase pointers in serial_table before calling usb_serial_put. Now, I am not yet 100% convinced that ref counting will, indeed, work. Atomics are known to have problems on SMP CPUs, which can reorder operations. But I would not discard atomics yet. Global mutex is go ugly. John __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
