On Mon, 29 Oct 2012, Richard Retanubun wrote: > do the disconnect without actually removing the power to the device. > I tried "echo 1 > /sys/bus/usb/drivers/usb/2-1.2/remove" and then take down > the power > but this produced the same leak signature even before I take down the power. > > Update on trigger to problem > ============================ > This will happen as the modem is powered down and /dev/ttyUSB from sierra is > teared down > either by powering it off/removing it, or sending at!reset. > > It does not happen when the same thing is done using a simple usb to serial > converter (pl2303) > > Focusing down on one of the dumps: > > unreferenced object 0xd3849740 (size 8): > comm "khubd", pid 1026, jiffies 232553037 (age 506.597s) > hex dump (first 8 bytes): > 4d 43 38 37 30 35 00 00 MC8705.. > backtrace: > [<e30efd74>] usb_cache_string+0x74/0xac [usbcore] > [<e30e77bc>] usb_enumerate_device+0x44/0xf8 [usbcore] > [<e30e7aa0>] usb_new_device+0x3c/0x13c [usbcore] > [<e30e9824>] hub_thread+0xc8c/0x1544 [usbcore] > [<c0043aa8>] kthread+0x7c/0x80 > [<c000ed48>] kernel_thread+0x4c/0x68 > > I have a small question. How does the memory kmalloc-ed() in usb_cache_string > is supposed to be released? > (during usb_serial_disconnect()?)
It doesn't get released during usb_serial_disconnect(). It gets released during usb_release_dev() in drivers/usb/core/usb.c. > Is the sierra driver is supposed to participate > in the tear down process (in sierra_release() maybe) and not doing something > that is expected? Probably not. > I am still missing the link between the actions done by the hub_thread() for > the caching the stings > and the sierra driver code. They aren't all that closely related. usb_release_dev() won't be called until all references to the USB device have been dropped. Maybe there's an extra reference hanging around. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
