From mboxrd@z Thu Jan 1 00:00:00 1970 From: Felipe Balbi Subject: Re: [RFC/PATCH] usb: musb: Prevent musb_am335x from being removed Date: Mon, 30 Jun 2014 13:44:26 -0500 Message-ID: <20140630184426.GU31442@saruman.home> References: <1399570060-28939-1-git-send-email-ezequiel@vanguardiasur.com.ar> Reply-To: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="ceuyUbi+oA5bUa/n" Return-path: Received: from arroyo.ext.ti.com ([192.94.94.40]:43134 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753840AbaF3Sou (ORCPT ); Mon, 30 Jun 2014 14:44:50 -0400 Content-Disposition: inline In-Reply-To: <1399570060-28939-1-git-send-email-ezequiel@vanguardiasur.com.ar> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Ezequiel Garcia Cc: linux-usb@vger.kernel.org, linux-omap@vger.kernel.org, Guido =?iso-8859-1?Q?Mart=EDnez?= , Tony Lindgren , Felipe Balbi , george.cherian@ti.com, Sebastian Andrzej Siewior , Greg Kroah-Hartman , yegorslists@googlemail.com --ceuyUbi+oA5bUa/n Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, On Thu, May 08, 2014 at 02:27:40PM -0300, Ezequiel Garcia wrote: > At probe time, the musb_am335x driver registers its childs by > calling of_platform_populate(), which registers all childs in > the devicetree hierarchy recursively. >=20 > On the other side, the driver's remove() function uses of_device_unregist= er() > to remove each child in the musb_am335x driver device struct. >=20 > However, when musb_dsps is loaded, its devices are attached to the musb_a= m335x > driver device struct as musb_am335x childs. Hence, musb_am335x remove() > will attempt to unregister the devices registered by musb_dsps, which pro= duces > a kernel panic. >=20 > In other words, the childs in the "struct device" hierarchy are not the s= ame > as the childs in the "devicetree" hierarchy. >=20 > Ideally, we should be enforcing the removal of the devices registered by > musb_am335x *only*, instead of all the child devices. However, because of= the > recursive nature of of_platform_populate, this doesn't seem possible. >=20 > Therefore, as the only solution at hand, this commit disables musb_am335x= driver > removal capability, preventing it from being ever removed. >=20 > Just for reference, here's the panic upon module removal: >=20 > musb-hdrc musb-hdrc.0.auto: remove, state 4 > usb usb1: USB disconnect, device number 1 > musb-hdrc musb-hdrc.0.auto: USB bus 1 deregistered > Unable to handle kernel NULL pointer dereference at virtual address 00000= 08c > pgd =3D de11c000 > [0000008c] *pgd=3D9e174831, *pte=3D00000000, *ppte=3D00000000 > Internal error: Oops: 17 [#1] ARM > Modules linked in: musb_am335x(-) musb_dsps musb_hdrc usbcore usb_common > CPU: 0 PID: 623 Comm: modprobe Not tainted 3.15.0-rc4-00001-g24efd13 #69 > task: de1b7500 ti: de122000 task.ti: de122000 > PC is at am335x_shutdown+0x10/0x28 > LR is at am335x_shutdown+0xc/0x28 > pc : [] lr : [] psr: a0000013 > sp : de123df8 ip : 00000004 fp : 00028f00 > r10: 00000000 r9 : de122000 r8 : c000e6c4 > r7 : de0e3c10 r6 : de0e3800 r5 : de624010 r4 : de1ec750 > r3 : de0e3810 r2 : 00000000 r1 : 00000001 r0 : 00000000 > Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user > Control: 10c5387d Table: 9e11c019 DAC: 00000015 > Process modprobe (pid: 623, stack limit =3D 0xde122240) > Stack: (0xde123df8 to 0xde124000) > 3de0: de0e3810 bf05= 4488 > 3e00: bf05444c de624010 60000013 bf043650 000012fc de624010 de0e3810 bf04= 3a20 > 3e20: de0e3810 bf04b240 c0635b88 c02ca37c c02ca364 c02c8db0 de1b7500 de0e= 3844 > 3e40: de0e3810 c02c8e28 c0635b88 de02824c de0e3810 c02c884c de0e3800 de0e= 3810 > 3e60: de0e3818 c02c5b20 bf05417c de0e3800 de0e3800 c0635b88 de0f2410 c02c= a838 > 3e80: bf05417c de0e3800 bf055438 c02ca8cc de0e3c10 bf054194 de0e3c10 c02c= a37c > 3ea0: c02ca364 c02c8db0 de1b7500 de0e3c44 de0e3c10 c02c8e28 c0635b88 de02= 824c > 3ec0: de0e3c10 c02c884c de0e3c10 de0e3c10 de0e3c18 c02c5b20 de0e3c10 de0e= 3c10 > 3ee0: 00000000 bf059000 a0000013 c02c5bc0 00000000 bf05900c de0e3c10 c02c= 5c48 > 3f00: de0dd0c0 de1ec970 de0f2410 bf05929c de0f2444 bf05902c de0f2410 c02c= a37c > 3f20: c02ca364 c02c8db0 bf05929c de0f2410 bf05929c c02c94c8 bf05929c 0000= 0000 > 3f40: 00000800 c02c8ab4 bf0592e0 c007fc40 c00dd820 6273756d 336d615f 0078= 3533 > 3f60: c064a0ac de1b7500 de122000 de1b7500 c000e590 00000001 c000e6c4 c006= 0160 > 3f80: 00028e70 00028e70 00028ea4 00000081 60000010 00028e70 00028e70 0002= 8ea4 > 3fa0: 00000081 c000e500 00028e70 00028e70 00028ea4 00000800 becb59f8 0002= 7608 > 3fc0: 00028e70 00028e70 00028ea4 00000081 00000001 00000001 00000000 0002= 8f00 > 3fe0: b6e6b6f0 becb59d4 000160e8 b6e6b6fc 60000010 00028ea4 00000000 0000= 0000 > [] (am335x_shutdown) from [] (dsps_musb_exit+0x3c/0x4= c [musb_dsps]) > [] (dsps_musb_exit [musb_dsps]) from [] (musb_shutdow= n+0x80/0x90 [musb_hdrc]) > [] (musb_shutdown [musb_hdrc]) from [] (musb_remove+0= x24/0x68 [musb_hdrc]) > [] (musb_remove [musb_hdrc]) from [] (platform_drv_re= move+0x18/0x1c) > [] (platform_drv_remove) from [] (__device_release_dr= iver+0x70/0xc8) > [] (__device_release_driver) from [] (device_release_= driver+0x20/0x2c) > [] (device_release_driver) from [] (bus_remove_device= +0xdc/0x10c) > [] (bus_remove_device) from [] (device_del+0x104/0x19= 8) > [] (device_del) from [] (platform_device_del+0x14/0x9= c) > [] (platform_device_del) from [] (platform_device_unr= egister+0xc/0x20) > [] (platform_device_unregister) from [] (dsps_remove+= 0x18/0x38 [musb_dsps]) > [] (dsps_remove [musb_dsps]) from [] (platform_drv_re= move+0x18/0x1c) > [] (platform_drv_remove) from [] (__device_release_dr= iver+0x70/0xc8) > [] (__device_release_driver) from [] (device_release_= driver+0x20/0x2c) > [] (device_release_driver) from [] (bus_remove_device= +0xdc/0x10c) > [] (bus_remove_device) from [] (device_del+0x104/0x19= 8) > [] (device_del) from [] (device_unregister+0xc/0x20) > [] (device_unregister) from [] (of_remove_populated_c= hild+0xc/0x14 [musb_am335x]) > [] (of_remove_populated_child [musb_am335x]) from [] = (device_for_each_child+0x44/0x70) > [] (device_for_each_child) from [] (am335x_child_remo= ve+0x18/0x30 [musb_am335x]) > [] (am335x_child_remove [musb_am335x]) from [] (platf= orm_drv_remove+0x18/0x1c) > [] (platform_drv_remove) from [] (__device_release_dr= iver+0x70/0xc8) > [] (__device_release_driver) from [] (driver_detach+0= xb4/0xb8) > [] (driver_detach) from [] (bus_remove_driver+0x4c/0x= a0) > [] (bus_remove_driver) from [] (SyS_delete_module+0x1= 28/0x1cc) > [] (SyS_delete_module) from [] (ret_fast_syscall+0x0/= 0x48) >=20 > Signed-off-by: Ezequiel Garcia can you send without RFC so it can be applied ? thank you --=20 balbi --ceuyUbi+oA5bUa/n Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJTsbAKAAoJEIaOsuA1yqREKbsP/jSamZmIepKkfRjGJxuD/jlR EHl7DLyxhwYILlX6Cr4k2gstyhbda/s9HPegjv8PP7HtVj+Ey2xpk4WV5bu9pmaz S4vEFixgsX8Wo4VBYGGMzwWEQ5WBUl0Z65PIP/sRUmLBsgppNicyxBZRQZtsqE2o Qxutqnz/KYKR8VdOzFmKf8wv86ImEGhxyNEfNIGV/iT5RBJnqoL+wz8j4A1U2rJp 917WInp6UyuxQpPBPnkxPSSRKZYyV6iEeCprW8cUUQsefwLxza4d1wSGJavSPvr0 05TroAm77zCYszFFzZaLsQTT+4Xd/gZR2pXFpmGdnAOXc2pb8C2djj46qn5R54qm B/I+q6GDcPI1D8Ih5KtqYsHSfZaBjaP6jukejydegqPU5eEkSi7s4yPD+SfdVHcR nACi1oURBJ9ahy5IbSY1j/N3cZFIjmaWUteATfT6ow2nSWViUkXBs4LJe+sg7rgb YBJJ2RY6x/GG9DxQqhbgwAOJ96vrnAmOob5giYQDYr40pbUhnQAQAKBkUc/XVJNl h3zzEz7ljX+NSRM5gWOJUCp3qZkoMbCfSwRtEgzjEWe40xGtWq5ErzLgOMZmRh+U DiyqoZv4d27TAnrAlZxgYHvaVoBzyd4fQcKUvcDBh5oHxNdho0JSkBC/Qs6GrAWu 7K5sL7gW7T1UCYa0Gerz =k6e6 -----END PGP SIGNATURE----- --ceuyUbi+oA5bUa/n--