Messages in this thread | | | Date | Tue, 13 Mar 2007 02:14:08 -0700 | From | Jim Radford <> | Subject | Re: [PATCH] usb-serial regression fix |
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On Mon, Mar 12, 2007 at 09:55:14PM -0400, Mark Lord wrote: > Jim Radford wrote: > >On Mon, Mar 12, 2007 at 05:18:19PM -0700, Greg KH wrote: > >>On Mon, Mar 12, 2007 at 03:59:22PM -0700, Jim Radford wrote: > >>>On Mon, Mar 12, 2007 at 03:42:35PM -0700, Jim Radford wrote: > >>>>On Mon, Mar 12, 2007 at 01:33:31PM -0700, Greg KH wrote: > >>>>>On Mon, Mar 12, 2007 at 04:22:22PM -0400, Mark Lord wrote: > >>>>>>Oliver Neukum wrote: > >>>>>>>>Mark Lord wrote: > >>>>>>>>>Okay, from that part (above), the problem is obvious: > >>>>>>>>>in that the "MCT U232 converter now disconnected" > >>>>>>>>>appears, and then we continue to try and call the > >>>>>>>>>driver's method.. Oops!
> >>>>>>>IMHO shutdown() is using serial->port[] and bombs. > >>>>>>>Could you reverse the order here?
> >>>Do not NULL serial->port[i] since it is used in ->shutdown(). > >>>This wasn't an issue until the order or ->shutdown() and > >>>device_unregister was corrected.
> >>> for (i = 0; i < serial->num_ports; ++i) > >>> if (serial->port[i]->dev.parent != NULL) { > >>> device_unregister(&serial->port[i]->dev); > >>>- serial->port[i] = NULL; > >>> }
> >>But shouldn't you null it out somewhere? It will be an "empty" > >>pointer at some point in time...
> >Not as far as I can see. The serial structure that ->port[i] is in > >gets kfree()ed soon after, in the same function, and nothing in > >between, other than ->shutdown(), uses ->port[]. I assume it was > >someone being overly cautious.
> So where does the memory get freed -- the structure pointed at > by the serial->port[i] thingie ? It's not a leak, is it?
It gets free'd through device_unregister
for (i = 0; i < num_ports; ++i) { ... port->dev.release = &port_release; ... retval = device_register(&port->dev);
which means that until all the drivers get converted to use ->port_probe() and ->port_remove() (which gets called by device_unregister) and stop using the ->port[] array in ->shutdown() we need to have ->shutdown() called before device_unregister.
> > > > Look at changeset d9a7ecacac5f8274d2afce09aadcf37bdb42b93a in Linus's > > > > tree from Jim Radford:
> > > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d9a7ecacac5f8274d2afce09aadcf37bdb42b93a
So, this patch should be reverted for now.
-Jim - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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