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Date: Tue, 4 Nov 2008 19:13:12 +0800 From: "Bryan Wu" <cooloney@...nel.org> To: "Lennert Buytenhek" <buytenh@...tstofly.org> Cc: netdev@...r.kernel.org, "Andy Fleming" <afleming@...escale.com>, "Byron Bradley" <byron.bbradley@...il.com>, "Tim Ellis" <tim.ellis@....com>, "Imre Kaloz" <kaloz@...nwrt.org>, "Nicolas Pitre" <nico@....org>, "Dirk Teurlings" <dirk@...xia.nl>, "Peter van Valderen" <p.v.valderen@...il.com> Subject: Re: [BUG] rmmod bfin_mac netdev driver module will cause system crash. On Tue, Nov 4, 2008 at 6:24 PM, Bryan Wu <cooloney@...nel.org> wrote: > On Tue, Nov 4, 2008 at 4:45 PM, Bryan Wu <cooloney@...nel.org> wrote: >> Hi Lennert, >> >> I got a regression since I update our blackfin kernel to the lastest >> 2.6.28-rc2 which includes your phylib patches. >> Please find the tracker here: >> https://blackfin.uclinux.org/gf/project/uclinux-dist/tracker/?action=TrackerItemEdit&tracker_id=141&tracker_item_id=4595 >> >> Briefly, the calling chain is: >> in bfin_mac_remove(), mdiobus_unregister() -> >> device_unregister(&bus->dev); -> put_device() -> kobject_put() -> >> kref_put(&kobj->kref, kobject_release); -> kobject_release() -> >> kobject_cleanup() -> mdiobus_release(). >> So in mdiobus_unregister() bus->state = MDIOBUS_UNREGISTERED; but in >> mdiobus_release(), this BUG_ON will fire: >> BUG_ON(bus->state != MDIOBUS_RELEASED); >> >> How about this patch? >> >> --- >> Index: drivers/net/phy/mdio_bus.c >> =================================================================== >> --- drivers/net/phy/mdio_bus.c (revision 5575) >> +++ drivers/net/phy/mdio_bus.c (working copy) >> @@ -134,13 +134,16 @@ >> int i; >> >> BUG_ON(bus->state != MDIOBUS_REGISTERED); >> - bus->state = MDIOBUS_UNREGISTERED; >> >> + bus->state = MDIOBUS_RELEASED; >> + >> device_unregister(&bus->dev); >> for (i = 0; i < PHY_MAX_ADDR; i++) { >> if (bus->phy_map[i]) >> device_unregister(&bus->phy_map[i]->dev); >> } >> + >> + bus->state = MDIOBUS_UNREGISTERED; >> } >> EXPORT_SYMBOL(mdiobus_unregister); >> --- >> >> This regression is gone, but I'm not sure whether there is some side effect. >> Please review. >> >> Thanks a lot >> -Bryan >> > > Oh, after applying this patch, I met a new WARN_ON issue: > --- > root:/> rmmod bfin_mac > ------------[ cut here ]------------ > WARNING: at lib/kobject.c:593 _kobject_put+0x4e/0x58() > kobject: '<NULL>' (0098f6a4): is not initialized, yet kobject_put() is > being called. > Modules linked in: bfin_mac(-) > Hardware Trace: > 0 Target : <0x0000485c> { _dump_stack + 0x0 } > Source : <0x0000e2fc> { _warn_slowpath + 0x58 } CALL pcrel > 1 Target : <0x0000e2fc> { _warn_slowpath + 0x58 } > Source : <0x000294aa> { _print_modules + 0x7a } RTS > 2 Target : <0x000294a4> { _print_modules + 0x74 } > Source : <0x0000e9b6> { _printk + 0x16 } RTS > 3 Target : <0x0000e9b2> { _printk + 0x12 } > Source : <0x0000f1e8> { _vprintk + 0x130 } RTS > 4 Target : <0x0000f1c8> { _vprintk + 0x110 } > Source : <0x0000f30c> { _vprintk + 0x254 } JUMP.S > 5 Target : <0x0000f30c> { _vprintk + 0x254 } > Source : <0x0000e826> { _wake_up_klogd + 0x1a } RTS > 6 Target : <0x0000e826> { _wake_up_klogd + 0x1a } > Source : <0x0000e818> { _wake_up_klogd + 0xc } IF !CC JUMP > 7 Target : <0x0000e80c> { _wake_up_klogd + 0x0 } > Source : <0x0000ec40> { _release_console_sem + 0x1b0 } JUMP.L > 8 Target : <0x0000ec38> { _release_console_sem + 0x1a8 } > Source : <0x0000ec2c> { _release_console_sem + 0x19c } IF !CC JUMP > 9 Target : <0x0000ec28> { _release_console_sem + 0x198 } > Source : <0x0000ec1a> { _release_console_sem + 0x18a } IF !CC JUMP > 10 Target : <0x0000ec14> { _release_console_sem + 0x184 } > Source : <0x00021de8> { _up + 0x3c } RTS > 11 Target : <0x00021de2> { _up + 0x36 } > Source : <0x00021dd4> { _up + 0x28 } IF !CC JUMP > 12 Target : <0x00021dac> { _up + 0x0 } > Source : <0x0000ec10> { _release_console_sem + 0x180 } CALL pcrel > 13 Target : <0x0000ebfc> { _release_console_sem + 0x16c } > Source : <0x0000eae2> { _release_console_sem + 0x52 } IF !CC JUMP > 14 Target : <0x0000eab2> { _release_console_sem + 0x22 } > Source : <0x0000ebde> { _release_console_sem + 0x14e } IF !CC JUMP > 15 Target : <0x0000ebd8> { _release_console_sem + 0x148 } > Source : <0x0000e776> { __call_console_drivers + 0x7e } RTS > Stack info: > SP: [0x00203cfc] <0x00203cfc> /* kernel dynamic memory */ > FP: (0x00203db4) > Memory from 0x00203cf0 to 00204000 > 00203cf0: ffffff16 00203cfc 001725e4 [0000e2fc]<0000e300> 00203d1c > 00142380 0016d044 > 00203d10: 00142380 00000251 00203d1c 626f6b5f 7463656a 7475705f > 3478302b 78302f65 > 00203d30: 00003835 0098e190 00c63fb0 002e9e9c <0000eb62> 0016d068 > 0016d068 0016d040 > 00203d50:<0000ebd8><0000ec14> 000032ea 00203df8 <0008e546> 00162b74 > 0000e9a0 0000001f > 00203d70: fffffff1 0016d070 <0000f30c> 00162b74 0000e9a0 00162b80 > 00000004 0000000f > 00203d90: 10624dd3 0097d4c4 00c63fb0 000000d0 000000d0 00203e34 > 00203db0 0000ffff > 00203db0: 00000000 (00000000)<00089f68><00089f7e> 0017b070 0017b070 > 001725e4 0017b070 > 00203dd0: 00000000 <0009f7fa> 0098f76c <0004da72> 037f5000 00c63f58 > <0009f828> 0098f76c > 00203df0: 0098f600 0017b008 002e9e9c 00203e20 <00089f16> 0098f6a4 > 00975800 000000ac > 00203e10: 00000002 00000002 0000002e 00203e2c 00000000 0098f6a4 > <0097cd34> 00975b80 > 00203e30: 00000002 00000001 0000001f <000a141a> 0016c084 0097def4 > 0016c130 00000068 > 00203e50: 00000001 00203e64 <000a14b6> 0016c084 0097def4 <000a08f2> > 0097e000 0097def4 > 00203e70:<000a08f8> 0097e000 0097def4 00000000 00000880 002e9e9c > <00109720> 0000001f > 00203e90:<0002a0e2> 0097e000 00000081 0000004c 001e9b94 <00043122> > 0017be00 6e696662 > 00203eb0: 63616d5f 00000000 00000000 00000000 00000000 00000000 > 00000000 00000000 > 00203ed0: 00000000 00000000 00000000 00000000 00000000 00000000 > 0097e000 00000880 > 00203ef0: 00203ef4 00000000 <ffa008d4> 00029f80 00000081 00000000 > ffffe000 0017c776 > 00203f10: 00c68de0 0015e23c 00000000 0000002e 00000002 002821ac > 00008000 00000000 > 00203f30: 00000000 00204000 002821ac 002821ac <0029d3c2><ffa00e3c> > 02002020 00192d99 > 00203f50: 0028cf9f 00192d92 0028cf96 00000000 0000000f 00000000 > 00000000 00000000 > 00203f70: 00000000 00000000 00000000 00000000 00000000 00000000 > 00000000 00000000 > 00203f90: 00000000 00000000 00000000 00000000 00000000 00000000 > 00000000 002d5f50 > 00203fb0: 002e9fe6 002e9e90 002e9e9c 00000001 002e9f80 0000004c > 002e0664 002e0664 > 00203fd0: 00000081 00000880 00000000 00000002 0000002e 00000000 > 002e065c 00000880 > 00203ff0: 002e065c 002e065c 00000081 00000006 00000000 > Return addresses in stack: > address : <0x0000e2fc> { _warn_slowpath + 0x58 } > address : <0x0000e300> { _warn_slowpath + 0x5c } > address : <0x0000eb62> { _release_console_sem + 0xd2 } > address : <0x0000ebd8> { _release_console_sem + 0x148 } > address : <0x0000ec14> { _release_console_sem + 0x184 } > address : <0x0008e546> { _vscnprintf + 0x16 } > address : <0x0000f30c> { _vprintk + 0x254 } > frame 1 : <0x00089f68> { _kobject_del + 0x10 } > address : <0x00089f7e> { _kobject_del + 0x26 } > address : <0x0009f7fa> { _device_del + 0x10a } > address : <0x0004da72> { _ilookup5 + 0x2e } > address : <0x0009f828> { _device_unregister + 0xc } > address : <0x00089f16> { _kobject_put + 0x4e } > address : <0x0097cd34> { :bfin_mac:_cleanup_module + 0x68 } > address : <0x000a141a> { ___device_release_driver + 0x5e } > address : <0x000a14b6> { _driver_detach + 0x72 } > address : <0x000a08f2> { _bus_remove_driver + 0x6a } > address : <0x000a08f8> { _bus_remove_driver + 0x70 } > address : <0x00109720> { _mutex_lock_interruptible + 0xc } > address : <0x0002a0e2> { _sys_delete_module + 0x162 } > address : <0x00043122> { _free_bprm + 0x12 } > address : <0xffa008d4> { _system_call + 0x68 } > address : <0x0029d3c2> [ rmmod + 0x1d382 ] > address : <0xffa00e3c> { _evt_system_call + 0x64 } > ---[ end trace 96c9ba4ee8d1eb27 ] > > This WARN was fired by this calling chain: mdiobus_unregister() -> > put_device() -> kobject_put(); > IMO, mdiobus_release should be called after mdiobus_free, right. So my > patch is not a good way to solve this bug. > Any idea about this? > > -Bryan > Hi guys, I guess I fixed this bug. we need to call device_unregister(&bus->dev); in mdiobus_free() not in mdiobus_unregister(). --- Index: drivers/net/phy/mdio_bus.c =================================================================== --- drivers/net/phy/mdio_bus.c (revision 5577) +++ drivers/net/phy/mdio_bus.c (working copy) @@ -136,7 +136,6 @@ BUG_ON(bus->state != MDIOBUS_REGISTERED); bus->state = MDIOBUS_UNREGISTERED; - device_unregister(&bus->dev); for (i = 0; i < PHY_MAX_ADDR; i++) { if (bus->phy_map[i]) device_unregister(&bus->phy_map[i]->dev); @@ -165,6 +164,7 @@ BUG_ON(bus->state != MDIOBUS_UNREGISTERED); bus->state = MDIOBUS_RELEASED; + device_unregister(&bus->dev); put_device(&bus->dev); } EXPORT_SYMBOL(mdiobus_free); --- If it is OK, I will send out a git patch for merge. -Bryan -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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