> -----Original Message----- > From: xiang xiao <xiaoxiang781216@xxxxxxxxx> > Sent: lundi 21 janvier 2019 14:22 > To: Loic PALLARDY <loic.pallardy@xxxxxx> > Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>; ohad@xxxxxxxxxx; > linux-remoteproc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Arnaud > POULIQUEN <arnaud.pouliquen@xxxxxx>; benjamin.gaignard@xxxxxxxxxx; s- > anna@xxxxxx > Subject: Re: [PATCH 1/1] remoteproc: fix recovery procedure > > On Fri, Jan 18, 2019 at 5:44 AM Loic PALLARDY <loic.pallardy@xxxxxx> wrote: > > > > > > > > > -----Original Message----- > > > From: linux-remoteproc-owner@xxxxxxxxxxxxxxx <linux-remoteproc- > > > owner@xxxxxxxxxxxxxxx> On Behalf Of Loic PALLARDY > > > Sent: jeudi 17 janvier 2019 21:52 > > > To: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx> > > > Cc: xiang xiao <xiaoxiang781216@xxxxxxxxx>; ohad@xxxxxxxxxx; linux- > > > remoteproc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Arnaud > > > POULIQUEN <arnaud.pouliquen@xxxxxx>; > benjamin.gaignard@xxxxxxxxxx; s- > > > anna@xxxxxx > > > Subject: RE: [PATCH 1/1] remoteproc: fix recovery procedure > > > > > > Hi Bjorn, > > > > > > > -----Original Message----- > > > > From: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx> > > > > Sent: jeudi 17 janvier 2019 19:00 > > > > To: Loic PALLARDY <loic.pallardy@xxxxxx> > > > > Cc: xiang xiao <xiaoxiang781216@xxxxxxxxx>; ohad@xxxxxxxxxx; linux- > > > > remoteproc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Arnaud > > > > POULIQUEN <arnaud.pouliquen@xxxxxx>; > benjamin.gaignard@xxxxxxxxxx; > > > s- > > > > anna@xxxxxx > > > > Subject: Re: [PATCH 1/1] remoteproc: fix recovery procedure > > > > > > > > On Mon 14 Jan 12:23 PST 2019, Loic PALLARDY wrote: > > > > > > > > > Hi Xiang, > > > > > > > > > > > -----Original Message----- > > > > > > From: xiang xiao <xiaoxiang781216@xxxxxxxxx> > > > > > > Sent: samedi 12 janvier 2019 19:29 > > > > > > To: Loic PALLARDY <loic.pallardy@xxxxxx> > > > > > > Cc: bjorn.andersson@xxxxxxxxxx; ohad@xxxxxxxxxx; linux- > > > > > > remoteproc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > Arnaud > > > > > > POULIQUEN <arnaud.pouliquen@xxxxxx>; > > > > benjamin.gaignard@xxxxxxxxxx; s- > > > > > > anna@xxxxxx > > > > > > Subject: Re: [PATCH 1/1] remoteproc: fix recovery procedure > > > > > > > > > > > > > > Thanks Loic for picking this up again. > > > > > > > > > > Hi Loic, > > > > > > The change just hide the problem, I think. The big issue is: > > > > > > 1.virtio devices aren't destroyed by rpproc_stop > > > > > Virtio devices are destroyed by rproc_stop() as vdev is registered as > rproc > > > > sub device. > > > > > rproc_stop() is calling rproc_stop_subdevices() which is in charge of > > > > removing virtio device and associated children. > > > > > rproc_vdev_do_stop() --> rproc_remove_virtio_dev() --> > > > > unregister_virtio_device() > > > > > > > > > > > > > Xiang is right, unregister_virtio_device() ends up decrementing the > > > > refcount of device and might free it, but it's not guaranteed. > > > > > > But it that case calling rproc_shutdown() doesn't guarantee devices are > free, > > > it is the same. > > > The only difference will be that rproc_vdev will be released by rproc and > > > then reallocated. So virtio device allocation is restarting with a virgin > memory > > > buffer. But you will have some ghost devices and restart may failed too. > > > I post a fix [1] last summer to be sure virtio device won't be released > while > > > still registered or registering... So there is still potential issue. > > > > > > > > > > > So I think we need to decouple the rproc_vdev and virtio_device, to > > > > allow the latter to potentially outlive the prior. > > > > > > > I checked how to decouple at least the allocation because one issue here. > > > The main issue is that all references are done based on container_of(). > > > I look for a fix having the less impacts on the current code, but still > possible to > > > create cross pointer references between rproc_vdev and virtio device. > > > It will clean up the memory allocation procedure, but the problem is still > > > there if sub virtio devices not well release. > > > We need to not be able to restart remote processor if at least one sub > device > > > was not correctly release... > > > > > > > > Please find below trace of a recovery on my ST SOC. My 2 rpmsg tty > are > > > > removed and re-inserted correctly > > > > > root@stm32mp1:~# ls /dev/ttyRPMSG* > > > > > /dev/ttyRPMSG0 /dev/ttyRPMSG1 > > > > > root@stm32mp1:~# [ 154.832523] remoteproc remoteproc0: crash > > > > detected in m4: type watchdog > > > > > [ 154.837725] remoteproc remoteproc0: handling crash #2 in m4 > > > > > [ 154.843319] remoteproc remoteproc0: recovering m4 > > > > > [ 154.849185] rpmsg_tty virtio0.rpmsg-tty-channel.-1.0: rpmsg tty > device > > > 0 > > > > is removed > > > > > [ 154.857572] rpmsg_tty virtio0.rpmsg-tty-channel.-1.1: rpmsg tty > device > > > 1 > > > > is removed > > > > > [ 155.382327] remoteproc remoteproc0: warning: remote FW > shutdown > > > > without ack > > > > > [ 155.387857] remoteproc remoteproc0: stopped remote processor > m4 > > > > > [ 155.398988] m4@0#vdev0buffer: assigned reserved memory node > > > > vdev0buffer@10044000 > > > > > [ 155.405910] virtio_rpmsg_bus virtio0: creating channel rpmsg-tty- > > > channel > > > > addr 0x0 > > > > > [ 155.413422] rpmsg_tty virtio0.rpmsg-tty-channel.-1.0: new channel: > > > > 0x400 -> 0x0 : ttyRPMSG0 > > > > > [ 155.421038] virtio_rpmsg_bus virtio0: creating channel rpmsg-tty- > > > channel > > > > addr 0x1 > > > > > [ 155.429088] rpmsg_tty virtio0.rpmsg-tty-channel.-1.1: new channel: > > > > 0x401 -> 0x1 : ttyRPMSG1 > > > > > [ 155.437338] virtio_rpmsg_bus virtio0: rpmsg host is online > > > > > [ 155.442401] m4@0#vdev0buffer: registered virtio0 (type 7) > > > > > [ 155.461154] remoteproc remoteproc0: remote processor m4 is now > up > > > > > ls /dev/ttyRPMSG* > > > > > /dev/ttyRPMSG0 /dev/ttyRPMSG1 > > > > > root@stm32mp1:~# > > > > > > > > > > As vdev is including in a larger struct allocated by rproc, it is safe > > > > > to set it to 0 before initializing virtio device while rproc subdevice > > > > > sequence is respected. > > > > > > > > > > > > > It's likely that this works in most use cases, but if for some reason > > > > there's additional references held those will operate on the object past > > > > your clearing of it. > > > > > > In fact, as the memory is free/kzalloc, virtio device fields are not all at 0 as > > > during boot sequence. > > > As mentioned below issue is coming from kobject state_initialized field > which > > > is not in a correct state. > > > This field is only set by kobject_init(). > > > I think normal way of working is to release memory when a device is no > more > > > used. > > > But another solution could be to reset it in kobject_cleanup() or > > > kobject_del() in order to have a symmetrical procedure. > > > > Reading some literature, it is a bad idea. > > Having a look to device_initialize () function description, it is clearly mention > device struct must be 0 (except fields provided by user) before. (Same in > kobject documentation) > > > > Extract drivers/base/core.c [1] > > * All fields in @dev must be initialized by the caller to 0, except > > * for those explicitly set to some other value. The simplest > > * approach is to use kzalloc() to allocate the structure containing > > * @dev. > > > > So memset or kfree/kzalloc of virtio_device manadatory. > > > As Bjorn note, it's very dangerous to do memset in rproc_vdev_do_probe > blindly, since subsystem or userspace may still hold the reference on > rpmsg device which will block the release process of virtio device. If > we do memset before the release, the later will make a panic mostly > like. Hi, As mentioned in my previous answer, doing a rproc_shutdown() and then a rproc_boot() is not safe at all for the same reason. The only safe way to proceed is to correlate the 2 devices as they don't have the same life cycle and to rely on device release mechanism to free structure. If a sub device is not correctly clean up, it will stay in the system, but it won't enter in conflict with remoteproc start sequence as a new object will be allocated... It is the responsibility of the customer to release correctly sub devices when a stop is requested. I'll send a v2 going in that way Regards, Loic > > > Regards, > > Loic > > > > [1]: > https://elixir.bootlin.com/linux/latest/source/drivers/base/core.c#L1482 > > > > > > Regards, > > > Loic > > > [1] https://patchwork.kernel.org/patch/10544757/ > > > > > > > > > > > Regards, > > > > Bjorn > > > > > > > > > > 2.and then rpmsg child devices aren't destroyed too > > > > > > Then, when the remote start and create rpmsg channel again, the > > > > > > duplicated channel will appear in kernel. > > > > > > To fix this problem, we need go through > rpproc_shutdown/rproc_boot > > > to > > > > > > destroy all devices(virtio and rpmsg) and create them again. > > > > > Rproc_shutdown/rproc_boot is solving the issue too, except if > > > > rproc_boot() was called several times and so rproc->power atomic not > > > equal > > > > to 1. > > > > > Using only rproc_stop() and rproc_start() allows to preserve rproc- > > > >power > > > > and so to be silent from rproc user pov. > > > > > > > > > > Regards, > > > > > Loic > > > > > > > > > > > > Thanks > > > > > > Xiang > > > > > > > > > > > > On Wed, Jan 9, 2019 at 6:56 PM Loic Pallardy <loic.pallardy@xxxxxx> > > > > wrote: > > > > > > > > > > > > > > Commit 7e83cab824a87e83cab824a8 ("remoteproc: Modify > recovery > > > > path > > > > > > > to use rproc_{start,stop}()") replaces rproc_{shutdown,boot}() > with > > > > > > > rproc_{stop,start}(), which skips destroy the virtio device at stop > > > > > > > but re-initializes it again at start. > > > > > > > > > > > > > > Issue is that struct virtio_dev is not correctly reinitialized like done > > > > > > > at initial allocation thanks to kzalloc() and kobject is considered as > > > > > > > already initialized by kernel. That is due to the fact struct > virtio_dev > > > > > > > is allocated and released at vdev resource handling level managed > > > and > > > > > > > virtio device is registered and unregistered at rproc subdevices > level. > > > > > > > > > > > > > > This patch initializes struct virtio_dev to 0 before using it and > > > > > > > registering it. > > > > > > > > > > > > > > Fixes: 7e83cab824a8 ("remoteproc: Modify recovery path to use > > > > > > rproc_{start,stop}()") > > > > > > > > > > > > > > Reported-by: Xiang Xiao <xiaoxiang781216@xxxxxxxxx> > > > > > > > Signed-off-by: Loic Pallardy <loic.pallardy@xxxxxx> > > > > > > > --- > > > > > > > drivers/remoteproc/remoteproc_virtio.c | 2 ++ > > > > > > > 1 file changed, 2 insertions(+) > > > > > > > > > > > > > > diff --git a/drivers/remoteproc/remoteproc_virtio.c > > > > > > b/drivers/remoteproc/remoteproc_virtio.c > > > > > > > index 183fc42a510a..88eade99395c 100644 > > > > > > > --- a/drivers/remoteproc/remoteproc_virtio.c > > > > > > > +++ b/drivers/remoteproc/remoteproc_virtio.c > > > > > > > @@ -332,6 +332,8 @@ int rproc_add_virtio_dev(struct > rproc_vdev > > > > *rvdev, > > > > > > int id) > > > > > > > struct virtio_device *vdev = &rvdev->vdev; > > > > > > > int ret; > > > > > > > > > > > > > > + /* Reset vdev struct as you don't know how it has been > > > previously > > > > > > used */ > > > > > > > + memset(vdev, 0, sizeof(struct virtio_device)); > > > > > > > vdev->id.device = id, > > > > > > > vdev->config = &rproc_virtio_config_ops, > > > > > > > vdev->dev.parent = dev; > > > > > > > -- > > > > > > > 2.7.4 > > > > > > >
