patch is against latest kernel 2.6.38
My testprog uss720test do a lot of bitbang - after hours i got following warning
and my machine lockups
Mar 17 17:32:27 lotus kernel: [ 7049.296037] ------------[ cut here ]------------
Mar 17 17:32:27 lotus kernel: [ 7049.299459] WARNING: at /build/buildd/linux-2.6.38/lib/kref.c:34
kref_get+0x21/0x30()
Mar 17 17:32:27 lotus kernel: [ 7049.302909] Hardware name: ProLiant ML350 G6
Mar 17 17:32:27 lotus kernel: [ 7049.306301] Modules linked in: nfsd nfs lockd exportfs fscache
nfs_acl auth_rpcgss sunrpc radeon uss720 ttm drm_kms_helper ipmi_devintf drm psmouse ppdev hpilo
serio_raw ipmi_si i7core
_edac edac_core ipmi_msghandler i2c_algo_bit parport shpchp power_meter usbhid hid tg3 e1000e hpsa
Mar 17 17:32:27 lotus kernel: [ 7049.317837] Pid: 1021, comm: uss720test Not tainted 2.6.38
Mar 17 17:32:27 lotus kernel: [ 7049.321689] Call Trace:
Mar 17 17:32:27 lotus kernel: [ 7049.325560] [<c1058c92>] ? warn_slowpath_common+0x72/0xa0
Mar 17 17:32:27 lotus kernel: [ 7049.329420] [<c127fbc1>] ? kref_get+0x21/0x30
Mar 17 17:32:27 lotus kernel: [ 7049.333309] [<c127fbc1>] ? kref_get+0x21/0x30
Mar 17 17:32:27 lotus kernel: [ 7049.337077] [<c1058ce2>] ? warn_slowpath_null+0x22/0x30
Mar 17 17:32:27 lotus kernel: [ 7049.340879] [<c127fbc1>] ? kref_get+0x21/0x30
Mar 17 17:32:27 lotus kernel: [ 7049.344648] [<f863a669>] ? T.557+0x1f9/0x490 [uss720]
Mar 17 17:32:27 lotus kernel: [ 7049.348412] [<f863ac13>] ? set_1284_register+0x83/0x120 [uss720]
Mar 17 17:32:27 lotus kernel: [ 7049.352215] [<f863af89>] ? parport_uss720_write_data+0x39/0x80
[uss720]
Mar 17 17:32:27 lotus kernel: [ 7049.356044] [<f8622ae7>] ? pp_do_ioctl.clone.2+0x4a7/0x7c0 [ppdev]
Mar 17 17:32:27 lotus kernel: [ 7049.359866] [<c107b9f3>] ? hrtimer_nanosleep+0x93/0x140
Mar 17 17:32:27 lotus kernel: [ 7049.363668] [<f8622e34>] ? pp_ioctl+0x34/0x50 [ppdev]
Mar 17 17:32:27 lotus kernel: [ 7049.367493] [<f8622e00>] ? pp_ioctl+0x0/0x50 [ppdev]
Mar 17 17:32:27 lotus kernel: [ 7049.371245] [<c1141c0b>] ? do_vfs_ioctl+0x7b/0x2e0
Mar 17 17:32:27 lotus kernel: [ 7049.374994] [<c1141ef7>] ? sys_ioctl+0x87/0x90
Mar 17 17:32:27 lotus kernel: [ 7049.378813] [<c100ab5f>] ? sysenter_do_call+0x12/0x28
Mar 17 17:32:27 lotus kernel: [ 7049.382447] ---[ end trace c0655632352fda62 ]---
After debugging uss720 driver i discovered that the completion callback was called
before usb_submit_urb returns.
The callback frees the request structure that is krefed on return by usb_submit_urb.
--- uss720.c.orig 2011-03-18 13:17:55.000000000 +0100
+++ uss720.c 2011-03-18 13:37:40.581204665 +0100
@@ -177,12 +177,12 @@
spin_lock_irqsave(&priv->asynclock, flags);
list_add_tail(&rq->asynclist, &priv->asynclist);
spin_unlock_irqrestore(&priv->asynclock, flags);
+ kref_get(&rq->ref_count);
ret = usb_submit_urb(rq->urb, mem_flags);
if (!ret) {
- kref_get(&rq->ref_count);
return rq;
}
- kref_put(&rq->ref_count, destroy_async);
+ destroy_async(&rq->ref_count);
err("submit_async_request submit_urb failed with %d", ret);
return NULL;
}
cu Peter
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