Messages in this thread | | | Date | Fri, 25 Apr 2008 09:53:01 +0200 | From | Stefan Richter <> | Subject | Re: [RFC/PATCH] usb-storage: wait for device scanning before mounting root |
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(Adding Cc: Matthew Wilcox)
Pekka J Enberg wrote: > Add a new kernel config option CONFIG_LATE_ROOT_MOUNT that makes the kernel > wait until background scanning of USB mass storage devices is complete before > attempting to mount the root filesystem. > > The config option is an alternative to the root_delay= kernel parameter > solution people currently use to boot from USB mass storage devices. [...] > drivers/scsi/scsi_scan.c | 2 ++ > drivers/usb/storage/usb.c | 3 +++ > include/linux/init.h | 12 ++++++++++++ > init/Kconfig | 5 +++++ > init/do_mounts.c | 32 ++++++++++++++++++++++++++++++++ > 5 files changed, 54 insertions(+) > > Index: linux-2.6/drivers/usb/storage/usb.c > =================================================================== > --- linux-2.6.orig/drivers/usb/storage/usb.c > +++ linux-2.6/drivers/usb/storage/usb.c > @@ -928,6 +928,7 @@ static int usb_stor_scan_thread(void * _ > /* Should we unbind if no devices were detected? */ > } > > + complete_root_scan(); > complete_and_exit(&us->scanning_done, 0); > } > > @@ -1007,12 +1008,14 @@ static int storage_probe(struct usb_inte > goto BadDevice; > } > > + begin_root_scan(); > /* Start up the thread for delayed SCSI-device scanning */ > th = kthread_create(usb_stor_scan_thread, us, "usb-stor-scan"); > if (IS_ERR(th)) { > printk(KERN_WARNING USB_STORAGE > "Unable to start the device-scanning thread\n"); > quiesce_and_remove_host(us); > + complete_root_scan(); > result = PTR_ERR(th); > goto BadDevice; > } [...] > Index: linux-2.6/drivers/scsi/scsi_scan.c > =================================================================== > --- linux-2.6.orig/drivers/scsi/scsi_scan.c > +++ linux-2.6/drivers/scsi/scsi_scan.c > @@ -1802,6 +1802,7 @@ static int do_scan_async(void *_data) > struct async_scan_data *data = _data; > do_scsi_scan_host(data->shost); > scsi_finish_async_scan(data); > + complete_root_scan(); > return 0; > } > > @@ -1823,6 +1824,7 @@ void scsi_scan_host(struct Scsi_Host *sh > return; > } > > + begin_root_scan(); > p = kthread_run(do_scan_async, data, "scsi_scan_%d", shost->host_no); > if (unlikely(IS_ERR(p))) > do_scan_async(data);
Looks like you want complete_root_scan() after IS_ERR(p). Are there any other thread exit paths which don't call complete_root_scan() yet?
Besides, can't you use the generic async scan facility of the SCSI stack for your purpose? If not, can it be extended to make it usable? -- Stefan Richter -=====-==--- -=-- ==--= http://arcgraph.de/sr/
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