Weongyo Jeong wrote:
On Wed, Sep 10, 2008 at 09:01:41AM -0700, Sam Leffler wrote:
Weongyo Jeong wrote:
weongyo 2008-09-10 03:40:51 UTC
FreeBSD src repository
Modified files:
sys/dev/usb if_zyd.c if_zydreg.h
Log:
SVN rev 182900 on 2008-09-10 03:40:51Z by weongyo
rename flags and add a ZYD_FLAG_DETACHING flag to indicate we're
detaching that when the USB is pulled out forcibly during the driver is
running background scan, a page fault can be occurred even if we called
usb_rem_task() when detaching. It looks like a kind of races.
If I understand the issue, it should be handled in the 802.11 state
machine. The device should be clocked to the INIT state and as a result
clear any outstanding tasks, timers, etc. The only reason you need to
do something special is if the h/w is gone and you need to guard against
accessing it.
Sam
This patch is to fix the below panic that it looks that it sometimes
occurs when we pull out USB stick forcibly during the driver's trying to
search channels or run background scan.
If we have a method to detect whether detach() is called by being pulled
out USB stick unexpectedly or detach() is called by operations of
kldunload(8), I think I can handle this case more flexibly. (I'm not
sure it's true. :-) Is there a way to detect this case or something I
missed?
I have no ideas yet how I can handle it in 802.11 state machine.
[EMAIL PROTECTED] /usr/src/sys/modules/zyd]# zyd0: at uhub3 port 4 (addr 2)
disconnected
zyd0: zyd_read sleep timeout
zyd0: could not send command (error=IOERROR)
zyd0: could not send command (error=IOERROR)
zyd0: could not send command (error=IOERROR)
zyd0: zyd_read sleep timeout
zyd0: could not send command (error=IOERROR)
zyd0: zyd_read sleep timeout
zyd0: could not send command (error=IOERROR)
zyd0: could not send command (error=IOERROR)
zyd0: could not send command (error=IOERROR)
zyd0: detached
Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address = 0x6a626f7f
fault code = supervisor read, page not present
instruction pointer = 0x20:0xc07908b6
stack pointer = 0x28:0xc3e30aec
frame pointer = 0x28:0xc3e30aec
code segment = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, def32 1, gran 1
processor eflags = interrupt enabled, resume, IOPL = 0
current process = 16 (usbtask-dr)
[thread pid 16 tid 100026 ]
Stopped at devclass_get_name+0x6: movl 0x14(%eax),%eax
db> bt
Tracing pid 16 tid 100026 td 0xc40cc8c0
devclass_get_name(6a626f6b,c3e30b14,c0790e77,deadc0de,ffffffff,...) at
devclass_get_name+0x6
device_get_name(deadc0de,ffffffff,0,c69c2a00,1,...) at device_get_name+0x1c
device_print_prettyname(deadc0de,c69c2a00,1,c69c2a00,c3e30bc4,...) at
device_print_prettyname+0x17
device_printf(deadc0de,c69cc297,100,c69cc290,3e8,...) at device_printf+0x12
zyd_cmd(2,c3e30be0,1,1,c3e5932c,...) at zyd_cmd+0x1f0
zyd_read16(c69cc567,c0bd8504,c3e30c10,c07aa70b,c69cc567,...) at zyd_read16+0x38
zyd_rfwrite(1,c69c2a00,c3e30c98,c69c9124,c69c2a08,...) at zyd_rfwrite+0x1c
zyd_al2230_set_channel(c69c2a08,2,c69cc567,ac7,0,...) at
zyd_al2230_set_channel+0x21
zyd_set_chan(c0ca30d0,0,c69cc567,ac7,c0c38d34,...) at zyd_set_chan+0x54
zyd_scantask(c69c2a00,0,5c,c0af321d,0,...) at zyd_scantask+0xe1
usb_task_thread(c0c38d34,c3e30d38,c0afb326,322,c40cc8c0,...) at
usb_task_thread+0xca
fork_exit(c06dcfd0,c0c38d34,c3e30d38) at fork_exit+0x112
fork_trampoline() at fork_trampoline+0x8
--- trap 0, eip = 0, esp = 0xc3e30d70, ebp = 0 ---
db>
In zyd_newstate the current code does this:
usb_rem_task(sc->sc_udev, &sc->sc_task);
/* do it in a process context */
sc->sc_state = nstate;
sc->sc_arg = arg;
if (nstate == IEEE80211_S_INIT) {
zvp->newstate(vap, nstate, arg);
return 0;
} else {
usb_add_task(sc->sc_udev, &sc->sc_task, USB_TASKQ_DRIVER);
return EINPROGRESS;
}
You need to clear any pending task callbacks, not just the one
associated with sc_udev (unless your callbacks do evil things like check
the current state to deal with races). The transition to the INIT state
must execute synchronously for multiple reasons (including detach); in
that case it looks like you must explicitly cancel the task that handles
scan-related work.
Sam
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