On Thu, 2013-12-19 at 10:26 -0800, Sarah Sharp wrote: > On Wed, Dec 18, 2013 at 04:05:05PM -0800, James Bottomley wrote: > > On Wed, 2013-12-18 at 16:50 -0500, Alan Stern wrote: > > > On Wed, 18 Dec 2013, Sarah Sharp wrote: > > > > > > > On Mon, Dec 16, 2013 at 07:10:19AM -0800, James Bottomley wrote: > > > > > This set should fix our target problems with USB by making the target > > > > > visibility properly reference counted. Since it's a major change to the > > > > > infrastructure, we'll incubate upstream first before backporting to > > > > > stable. > > > > > > > > > > James > > > > > > > > I tried these patches, and they cause an oops when a USB mass storage > > > > device is plugged in. Note that this device uses the usb-storage > > > > driver, not the uas driver. > > > > > > > > [14248.340064] scsi6 : usb-storage 2-2:1.0 > > > > [14248.341083] usbcore: registered new interface driver usb-storage > > > > [14248.346211] usbcore: registered new interface driver uas > > > > [14249.339937] scsi 6:0:0:0: Direct-Access Lexar JumpDrive 1.00 PQ: 0 ANSI: 6 > > > > [14249.340988] ------------[ cut here ]------------ > > > > [14249.340999] WARNING: CPU: 3 PID: 5578 at lib/kobject.c:227 kobject_add_internal+0x13f/0x350() > > > > [14249.341003] kobject_add_internal failed for 6:0:0:0 (error: -2 parent: target6:0:0) > > > > [14249.341005] Modules linked in: uas usb_storage ctr ccm cuse dm_crypt uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_core videodev btusb x86_pkg_temp_thermal coretemp ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd arc4 iwldvm mac80211 microcode snd_hda_codec_hdmi iwlwifi psmouse snd_hda_codec_realtek serio_raw snd_hda_intel snd_usb_audio snd_hda_codec thinkpad_acpi cfg80211 joydev snd_usbmidi_lib nvram snd_hwdep snd_seq_midi snd_pcm snd_seq_midi_event snd_rawmidi lpc_ich rfcomm bnep snd_seq bluetooth snd_seq_device snd_page_alloc ehci_pci snd_timer ehci_hcd snd soundcore tpm_tis binfmt_misc btrfs libcrc32c xor raid6_pq hid_generic usbhid hid i915 ahci libahci e1000e sdhci_pci sdhci i2c_algo_bit drm_kms_helper ptp pps_core drm xhci_hcd video > > > > [14249.341095] CPU: 3 PID: 5578 Comm: kworker/u16:0 Not tainted 3.13.0-rc1+ #142 > > > > [14249.341098] Hardware name: LENOVO 2325AP7/2325AP7, BIOS G2ET82WW (2.02 ) 09/11/2012 > > > > [14249.341105] Workqueue: events_unbound async_run_entry_fn > > > > [14249.341108] 0000000000000009 ffff88003aa9db60 ffffffff81658a4e ffff88003aa9dba8 > > > > [14249.341115] ffff88003aa9db98 ffffffff81048c3d ffff88006bc551b0 00000000fffffffe > > > > [14249.341121] 0000000000000000 ffff8800bec22838 0000000000000200 ffff88003aa9dbf8 > > > > [14249.341127] Call Trace: > > > > [14249.341135] [<ffffffff81658a4e>] dump_stack+0x4d/0x66 > > > > [14249.341142] [<ffffffff81048c3d>] warn_slowpath_common+0x7d/0xa0 > > > > [14249.341148] [<ffffffff81048cac>] warn_slowpath_fmt+0x4c/0x50 > > > > [14249.341154] [<ffffffff81660f17>] ? _raw_spin_unlock+0x27/0x40 > > > > [14249.341159] [<ffffffff8133748f>] kobject_add_internal+0x13f/0x350 > > > > [14249.341163] [<ffffffff813379b5>] kobject_add+0x65/0xb0 > > > > [14249.341170] [<ffffffff81425b40>] ? get_device+0x30/0x30 > > > > [14249.341175] [<ffffffff81649781>] ? klist_init+0x31/0x40 > > > > [14249.341181] [<ffffffff81427208>] device_add+0x128/0x660 > > > > [14249.341186] [<ffffffff814369cc>] ? __pm_runtime_resume+0x5c/0x90 > > > > [14249.341193] [<ffffffff8145bcdc>] scsi_sysfs_add_sdev+0xac/0x340 > > > > [14249.341199] [<ffffffff8145a443>] do_scan_async+0x83/0x180 > > > > [14249.341204] [<ffffffff81074247>] async_run_entry_fn+0x37/0x130 > > > > [14249.341210] [<ffffffff81066524>] process_one_work+0x1f4/0x550 > > > > [14249.341215] [<ffffffff810664c2>] ? process_one_work+0x192/0x550 > > > > [14249.341220] [<ffffffff81067261>] worker_thread+0x121/0x3a0 > > > > [14249.341225] [<ffffffff81067140>] ? manage_workers.isra.22+0x2a0/0x2a0 > > > > [14249.341231] [<ffffffff8106dc8c>] kthread+0xfc/0x120 > > > > [14249.341238] [<ffffffff8106db90>] ? kthread_create_on_node+0x230/0x230 > > > > [14249.341243] [<ffffffff81669cac>] ret_from_fork+0x7c/0xb0 > > > > [14249.341249] [<ffffffff8106db90>] ? kthread_create_on_node+0x230/0x230 > > > > [14249.341253] ---[ end trace 7f1d8a449e6af5aa ]--- > > > > [14249.341259] scsi 6:0:0:0: failed to add device: -2 > > > > > > James: > > > > > > The problem occurs when scsi_finish_async_scan() calls > > > scsi_sysfs_add_devices(). > > > > > > During an async scan, the devices get stored up and not made visible as > > > they are found (see the end of scsi_add_lun()). At the end, the target > > > gets removed because it has no visible children, of course. Then when > > > the children do get added all at once, when the scan is over, it's too > > > late. > > > > > > How should this be fixed? Forget about the en-masse registration and > > > do each device as it is found? > > > > Great, I knew I'd find a reason to hate the async scanning code > > eventually. > > > > However, the solution is just to make the kref work for us. We already > > properly refcount everything, so we just take the reap_ref on the target > > at the point the disk has to go through the remove device path, then > > just rely on refcounting ... a bit like this. > > Do you want me to test this? If so, should I apply it on top of the > previous patches, or separately? It should apply incrementally on top of the previous two. If it actually works, I'll fold it into the first patch. Thanks, James -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
