linux-kernel - [PATCH 0/7] HID: picoLCD updates

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Message-ID: <20120730213656.0a9f6d30@neptune.home>
Date:	Mon, 30 Jul 2012 21:36:56 +0200
From:	Bruno Prémont <bonbons@...ux-vserver.org>
To:	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	Jiri Kosina <jkosina@...e.cz>
Cc:	Jaya Kumar <jayalk@...works.biz>, linux-fbdev@...r.kernel.org
Subject: [PATCH 0/7] HID: picoLCD updates

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]

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.

[ 6383.521833] =============================================================================
[ 6383.530020] BUG kmalloc-64 (Not tainted): Object already free
[ 6383.530020] -----------------------------------------------------------------------------
[ 6383.530020] 
[ 6383.530020] INFO: Slab 0xdde0ea20 objects=51 used=40 fp=0xcef516e0 flags=0x40000080
[ 6383.530020] INFO: Object 0xcef51190 @offset=400 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
[ 6383.530020] FIX kmalloc-64: Object at 0xcef51190 not freed

or worse spontaneous reboot of the system without any trace on netconsole or
serial console.

echo $devid > bind; echo $devid > unbind
or
echo $devid > bind; echo $devid > unbind; sleep 0.2; echo $devid > bind; echo $devid > unbind

is sufficient to trigger the above issue while waiting a few seconds between bind and unbind
shows no sign of trouble.

Suggestions as to how to debug this and fix it are welcome!

Thanks,
Bruno
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