Messages in this thread | | | Date | Wed, 06 Sep 2006 18:50:48 +0200 | From | Stefan Richter <> | Subject | Re: 2.6.18-rc5-mm1 + all hotfixes -- INFO: possible recursive locking detected |
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I wrote: > I wrote: >> Or maybe it's older. Nodemgr takes class->subsys.rwsem and >> device.bus->subsys.rwsem. It always did. Could there be a change in >> driver core which makes this recursive? Or has it always been recursive? >> For example, >> >> static void nodemgr_update_pdrv(struct node_entry *ne) >> { >> struct unit_directory *ud; >> struct hpsb_protocol_driver *pdrv; >> struct class *class = &nodemgr_ud_class; >> struct class_device *cdev; >> >> down_read(&class->subsys.rwsem); >> list_for_each_entry(cdev, &class->children, node) {
This may be wrong anyway. According to include/linux/device.h, class->sem should be used to protect access to class->children. There are more places in nodemgr of this sort.
>> ud = container_of(cdev, struct unit_directory, class_dev); >> if (ud->ne != ne || !ud->device.driver) >> continue; >> >> pdrv = container_of(ud->device.driver, struct hpsb_protocol_driver, driver); >> >> if (pdrv->update && pdrv->update(ud)) { >> down_write(&ud->device.bus->subsys.rwsem); >> device_release_driver(&ud->device); >> up_write(&ud->device.bus->subsys.rwsem); >> } >> } >> up_read(&class->subsys.rwsem); >> } > > Hi Greg, > > perhaps you could advise on this. It appears from grepping through the > sources that drivers/ieee1394/nodemgr.c is the only one with mixed > access to device.bus->subsys.rwsem and class->subsys.rwsem. > > Other usages of subsys.rwsem that I found are: > 1a.) dev->bus->subsys.rwsem > driver/ide/ide-proc.c and drivers/net/phy/phy_device.c take > dev->bus->subsys.rwsem. drivers/pnp/card.c takes dev.bus->subsys.rwsem. > > 1b.) driver.bus->subsys.rwsem > drivers/s390/net/qeth_proc.c takes driver.bus->subsys.rwsem. > > 2.) class->subsys.rwsem > drivers/scsi/hosts.c takes class->subsys.rwsem. > > 3.) bustype.subsys.rwsem > drivers/input/serio/serio.c takes serio_bus.subsys.rwsem. > drivers/input/gameport/gameport.c takes gameport_bus.subsys.rwsem. > drivers/base/power/shutdown.c takes devices_subsys.rwsem. > drivers/usb/core/devices.c and devio.c take usb_bus_type.subsys.rwsem. > > Do class->subsys.rwsem, bus->subsys.rwsem, and bus_type.subsys.rwsem > point to identical or different lock instances? > > Either way, could it hurt to convert nodemgr to uniformly use > ieee1394_bus_type.subsys.rwsem all over the place? > > Thanks,
-- Stefan Richter -=====-=-==- =--= --==- http://arcgraph.de/sr/ - 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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