On Fri, Sep 28, 2012 at 08:52:43AM +0800, Ming Lei wrote: > Inside bus_add_driver(), one device might be added into > the bus or probed which is triggered by deferred probe > just after completing of driver_attach() and before > 'klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers)', > so the device won't be probed by this driver. > > This patch moves the below line > > 'klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers)' > > before driver_attach() inside bus_add_driver(). > > So fixes the problem since the below way can guarantee that > no probe(dev) may be lost. > > CPU0 CPU1 > driver_register > ... > write(bus->driver_list) > smp_mb() > read(bus->device_list) > ... > device_add > /* bus_add_device */ > write(bus->device_list) > smp_mb() > /* bus_probe_device*/ > read(bus->driver_list) > > And the smp_mb() has been implicit by UNLOCK+LOCK > of 'klist' according to 'VARIETIES OF MEMORY BARRIER' part > of Documentation/memory-barriers.txt. > > Reported-and-Tested-by: Russell King <[email protected]>
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