Re: [PATCH 0/7] HID: picoLCD updates

["Bruno Prémont" <bonbons@linux-vserver.org>]

Hi Jiri,

On Wed, 15 August 2012 Jiri Kosina <jkosina@suse.cz> wrote:
> On Mon, 30 Jul 2012, Bruno Prémont wrote:
> > Hi,
> > 
> > This series updates picoLCD driver:
> > - split the driver functions into separate files which get included
> >   depending on Kconfig selection
> >   (implementation for CIR using RC_CORE will follow later)
> > - drop private framebuffer refcounting in favor of refcounting added
> >   to fb_info some time ago
> > - fix various bugs issues
> > - disabled firmware version checking in probe() as it does not work
> >   anymore since commit 4ea5454203d991ec85264f64f89ca8855fce69b0
> >   [HID: Fix race condition between driver core and ll-driver]
> 
> I have now applied the series to my 'picolcd' branch, except for 6/7, 
> please see the comment I sent to it separately.

Will respin that one soon

> > Note: I still get weird behavior on quick unbind/bind sequences
> > issued via sysfs (CONFIG_SMP=n system) that are triggered by framebuffer
> > support and apparently more specifically fb_defio part of it.
> > 
> > Unfortunately I'm out of ideas as to how to track down the problem which
> > shows either as SLAB corruption (detected with SLUB debugging, e.g.
> 
> Would be nice to have this sorted out before the next merge window indeed, 
> so that it can go in together with the rest of the changes.
> 
> > 
> > [ 6383.521833] ======================================> > [ 6383.530020] BUG kmalloc-64 (Not tainted): Object already free
> > [ 6383.530020] -----------------------------------------------------------------------------
> > [ 6383.530020] 
> > [ 6383.530020] INFO: Slab 0xdde0ea20 objectsQ used@ fp=0xcef516e0 flags=0x40000080
> > [ 6383.530020] INFO: Object 0xcef51190 @offset@0 fp=0xcef51f50
> > [ 6383.530020] 
> > [ 6383.530020] Bytes b4 cef51180: cc cc cc cc d0 12 f5 ce 5a 5a 5a 5a 5a 5a 5a 5a  ........ZZZZZZZZ
> > [ 6383.530020] Object cef51190: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
> > [ 6383.530020] Object cef511a0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
> > [ 6383.530020] Object cef511b0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
> > [ 6383.530020] Object cef511c0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5  kkkkkkkkkkkkkkk.
> > [ 6383.530020] Redzone cef511d0: bb bb bb bb                                      ....
> > [ 6383.530020] Padding cef511d8: 5a 5a 5a 5a 5a 5a 5a 5a                          ZZZZZZZZ
> > [ 6383.530020] Pid: 1922, comm: bash Not tainted 3.5.0-jupiter-00003-g8d858b1-dirty #2
> > [ 6383.530020] Call Trace:
> > [ 6383.530020]  [<c10bd3cc>] print_trailer+0x11c/0x130
> > [ 6383.530020]  [<c10bd415>] object_err+0x35/0x40
> > [ 6383.530020]  [<c10be809>] free_debug_processing+0x99/0x200
> > [ 6383.530020]  [<c10bf77e>] __slab_free+0x2e/0x280
> > [ 6383.530020]  [<c1322284>] ? hid_submit_out+0xa4/0x120
> > [ 6383.530020]  [<c1322870>] ? __usbhid_submit_report+0xc0/0x3c0
> > [ 6383.530020]  [<c10bfbda>] ? kfree+0xfa/0x110
> > [ 6383.530020]  [<de932aa4>] ? picolcd_debug_out_report+0x8c4/0x8e0 [hid_picolcd]
> > [ 6383.530020]  [<c10bfbda>] kfree+0xfa/0x110
> > [ 6383.530020]  [<c1322284>] ? hid_submit_out+0xa4/0x120
> > [ 6383.530020]  [<c1322284>] ? hid_submit_out+0xa4/0x120
> > [ 6383.530020]  [<c1322284>] ? hid_submit_out+0xa4/0x120
> > [ 6383.530020]  [<c1322284>] hid_submit_out+0xa4/0x120
> > [ 6383.530020]  [<c1322908>] __usbhid_submit_report+0x158/0x3c0
> > [ 6383.530020]  [<c1322c2b>] usbhid_submit_report+0x1b/0x30
> > [ 6383.530020]  [<de930789>] picolcd_fb_reset+0xb9/0x180 [hid_picolcd]
> > [ 6383.530020]  [<de930f1d>] picolcd_init_framebuffer+0x20d/0x2e0 [hid_picolcd]
> > [ 6383.530020]  [<de92fb9c>] picolcd_probe+0x3cc/0x580 [hid_picolcd]
> > [ 6383.530020]  [<c1319147>] hid_device_probe+0x67/0xf0
> > [ 6383.530020]  [<c1282f97>] ? driver_sysfs_add+0x57/0x80
> > [ 6383.530020]  [<c128329d>] driver_probe_device+0xbd/0x1c0
> > [ 6383.530020]  [<c1318a1b>] ? hid_match_device+0x7b/0x90
> > [ 6383.530020]  [<c12821e5>] driver_bind+0x75/0xd0
> > [ 6383.530020]  [<c1282170>] ? driver_unbind+0x90/0x90
> > [ 6383.530020]  [<c12818b7>] drv_attr_store+0x27/0x30
> > [ 6383.530020]  [<c1114aec>] sysfs_write_file+0xac/0xf0
> > [ 6383.530020]  [<c10c794c>] vfs_write+0x9c/0x130
> > [ 6383.530020]  [<c10d4a1f>] ? sys_dup3+0x11f/0x160
> > [ 6383.530020]  [<c1114a40>] ? sysfs_poll+0x90/0x90
> > [ 6383.530020]  [<c10c7bbd>] sys_write+0x3d/0x70
> > [ 6383.530020]  [<c13f2557>] sysenter_do_call+0x12/0x26
> 
> So I am wondering whether the path this happens on is
> 
>                 if (!test_bit(HID_OUT_RUNNING, &usbhid->iofl)) {
>                         usbhid_restart_out_queue(usbhid);
> 
> in __usbhid_submit_report(). It would then indicate perhaps some race with 
> iofl handling.

Huh, that specific test_bit hunk I can't find in __usbhid_submit_report,
is that 3.6 material?
I'm running my tests against 3.5...

The nearest I have is:
                                if (!test_bit(HID_OUT_RUNNING, &usbhid->iofl))
                                        if (!irq_out_pump_restart(hid))
                                                set_bit(HID_OUT_RUNNING, &usbhid->iofl);


> Could you please stick some printk() just before and after this 
> usbhid_restart_out_queue() call, so that we know that it's this triggering 
> it?

Thanks,
Bruno