Re: [PATCH] powerpc/vio: use simple dummy struct device as bus parent
On Thu, Oct 03, 2019 at 03:10:03PM -0400, Dan Streetman wrote:
> On Fri, Sep 27, 2019 at 2:19 PM Greg Kroah-Hartman
> wrote:
> >
> > On Fri, Sep 27, 2019 at 09:04:02AM -0400, Dan Streetman wrote:
> > > The dummy vio_bus_device creates the /sys/devices/vio directory, which
> > > contains real vio devices under it; since it represents itself as having
> > > a bus = _bus_type, its /sys/devices/vio/uevent does call the bus's
> > > .uevent function, vio_hotplug(), and as that function won't find a real
> > > device for the dummy vio_dev, it will return -ENODEV.
> > >
> > > One of the main users of the uevent node is udevadm, e.g. when it is
> > > called
> > > with 'udevadm trigger --devices'. Up until recently, it would ignore any
> > > errors returned when writing to devices' uevent file, but it was recently
> > > changed to start returning error if it gets an error writing to any uevent
> > > file:
> > > https://github.com/systemd/systemd/commit/97afc0351a96e0daa83964df33937967c75c644f
> > >
> > > since the /sys/devices/vio/uevent file has always returned ENODEV from
> > > any write to it, this now causes the udevadm trigger command to return
> > > an error. This may be fixed in udevadm to ignore ENODEV errors, but the
> > > vio driver should still be fixed.
> > >
> > > This patch changes the arch/powerpc/platform/pseries/vio.c 'dummy'
> > > parent device into a real dummy device with no .bus, so its uevent
> > > file will stop returning ENODEV and simply do nothing and return 0.
> > >
> > > Signed-off-by: Dan Streetman
> > > ---
> > > arch/powerpc/platforms/pseries/vio.c | 11 ---
> > > 1 file changed, 4 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/arch/powerpc/platforms/pseries/vio.c
> > > b/arch/powerpc/platforms/pseries/vio.c
> > > index 79e2287991db..63bc16631680 100644
> > > --- a/arch/powerpc/platforms/pseries/vio.c
> > > +++ b/arch/powerpc/platforms/pseries/vio.c
> > > @@ -32,11 +32,8 @@
> > > #include
> > > #include
> > >
> > > -static struct vio_dev vio_bus_device = { /* fake "parent" device */
> > > - .name = "vio",
> > > - .type = "",
> > > - .dev.init_name = "vio",
> > > - .dev.bus = _bus_type,
> > > +static struct device vio_bus = {
> > > + .init_name = "vio",
> >
> > Eeek, no! Why are you creating a static device that will then be
> > reference counted? Not nice :(
>
> so, I looked again and it seems quite a few places appear to do
> exactly this, is it something that should be fixed?
Yes.
Re: [PATCH] powerpc/vio: use simple dummy struct device as bus parent
On Fri, Sep 27, 2019 at 2:19 PM Greg Kroah-Hartman
wrote:
>
> On Fri, Sep 27, 2019 at 09:04:02AM -0400, Dan Streetman wrote:
> > The dummy vio_bus_device creates the /sys/devices/vio directory, which
> > contains real vio devices under it; since it represents itself as having
> > a bus = _bus_type, its /sys/devices/vio/uevent does call the bus's
> > .uevent function, vio_hotplug(), and as that function won't find a real
> > device for the dummy vio_dev, it will return -ENODEV.
> >
> > One of the main users of the uevent node is udevadm, e.g. when it is called
> > with 'udevadm trigger --devices'. Up until recently, it would ignore any
> > errors returned when writing to devices' uevent file, but it was recently
> > changed to start returning error if it gets an error writing to any uevent
> > file:
> > https://github.com/systemd/systemd/commit/97afc0351a96e0daa83964df33937967c75c644f
> >
> > since the /sys/devices/vio/uevent file has always returned ENODEV from
> > any write to it, this now causes the udevadm trigger command to return
> > an error. This may be fixed in udevadm to ignore ENODEV errors, but the
> > vio driver should still be fixed.
> >
> > This patch changes the arch/powerpc/platform/pseries/vio.c 'dummy'
> > parent device into a real dummy device with no .bus, so its uevent
> > file will stop returning ENODEV and simply do nothing and return 0.
> >
> > Signed-off-by: Dan Streetman
> > ---
> > arch/powerpc/platforms/pseries/vio.c | 11 ---
> > 1 file changed, 4 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/powerpc/platforms/pseries/vio.c
> > b/arch/powerpc/platforms/pseries/vio.c
> > index 79e2287991db..63bc16631680 100644
> > --- a/arch/powerpc/platforms/pseries/vio.c
> > +++ b/arch/powerpc/platforms/pseries/vio.c
> > @@ -32,11 +32,8 @@
> > #include
> > #include
> >
> > -static struct vio_dev vio_bus_device = { /* fake "parent" device */
> > - .name = "vio",
> > - .type = "",
> > - .dev.init_name = "vio",
> > - .dev.bus = _bus_type,
> > +static struct device vio_bus = {
> > + .init_name = "vio",
>
> Eeek, no! Why are you creating a static device that will then be
> reference counted? Not nice :(
so, I looked again and it seems quite a few places appear to do
exactly this, is it something that should be fixed?
$ git grep 'static struct device [^*{]*{'
arch/arm/kernel/dma-isa.c:static struct device isa_dma_dev = {
arch/arm/mach-rpc/dma.c:static struct device isa_dma_dev = {
arch/arm/mach-s3c24xx/s3c2410.c:static struct device s3c2410_dev = {
arch/arm/mach-s3c24xx/s3c2412.c:static struct device s3c2412_dev = {
arch/arm/mach-s3c24xx/s3c2416.c:static struct device s3c2416_dev = {
arch/arm/mach-s3c24xx/s3c2440.c:static struct device s3c2440_dev = {
arch/arm/mach-s3c24xx/s3c2442.c:static struct device s3c2442_dev = {
arch/arm/mach-s3c24xx/s3c2443.c:static struct device s3c2443_dev = {
arch/arm/mach-s3c64xx/common.c:static struct device s3c64xx_dev = {
arch/arm/mach-s3c64xx/s3c6400.c:static struct device s3c6400_dev = {
arch/arm/mach-s3c64xx/s3c6410.c:static struct device s3c6410_dev = {
arch/mips/sgi-ip22/ip22-gio.c:static struct device gio_bus = {
arch/parisc/kernel/drivers.c:static struct device root = {
arch/powerpc/platforms/ps3/system-bus.c:static struct device ps3_system_bus = {
arch/powerpc/platforms/pseries/ibmebus.c:static struct device
ibmebus_bus_device = { /* fake "parent" device */
arch/powerpc/platforms/pseries/vio.c:static struct device vio_bus = {
arch/um/drivers/virtio_uml.c:static struct device vu_cmdline_parent = {
drivers/base/isa.c:static struct device isa_bus = {
drivers/block/rbd.c:static struct device rbd_root_dev = {
drivers/gpu/drm/ttm/ttm_module.c:static struct device ttm_drm_class_device = {
drivers/iio/dummy/iio_dummy_evgen.c:static struct device iio_evgen_dev = {
drivers/iio/trigger/iio-trig-sysfs.c:static struct device iio_sysfs_trig_dev = {
drivers/misc/sgi-gru/grumain.c:static struct device gru_device = {
drivers/nubus/bus.c:static struct device nubus_parent = {
drivers/sh/maple/maple.c:static struct device maple_bus = {
drivers/sh/superhyway/superhyway.c:static struct device
superhyway_bus_device = {
drivers/soc/fsl/qe/qe_ic.c:static struct device device_qe_ic = {
drivers/virtio/virtio_mmio.c:static struct device vm_cmdline_parent = {
kernel/time/clockevents.c:static struct device tick_bc_dev = {
kernel/time/clocksource.c:static struct device device_clocksource = {
>
> What's wrong with a simple call to device_create() for your "fake"
> device you want to make here? That's what it is there for :)
>
> thanks,
>
> greg k-h
Re: [PATCH] powerpc/vio: use simple dummy struct device as bus parent
On Sat, Sep 28, 2019 at 3:41 AM Greg Kroah-Hartman
wrote:
>
> On Fri, Sep 27, 2019 at 03:48:49PM -0400, Dan Streetman wrote:
> > On Fri, Sep 27, 2019 at 2:19 PM Greg Kroah-Hartman
> > wrote:
> > >
> > > On Fri, Sep 27, 2019 at 09:04:02AM -0400, Dan Streetman wrote:
> > > > The dummy vio_bus_device creates the /sys/devices/vio directory, which
> > > > contains real vio devices under it; since it represents itself as having
> > > > a bus = _bus_type, its /sys/devices/vio/uevent does call the bus's
> > > > .uevent function, vio_hotplug(), and as that function won't find a real
> > > > device for the dummy vio_dev, it will return -ENODEV.
> > > >
> > > > One of the main users of the uevent node is udevadm, e.g. when it is
> > > > called
> > > > with 'udevadm trigger --devices'. Up until recently, it would ignore
> > > > any
> > > > errors returned when writing to devices' uevent file, but it was
> > > > recently
> > > > changed to start returning error if it gets an error writing to any
> > > > uevent
> > > > file:
> > > > https://github.com/systemd/systemd/commit/97afc0351a96e0daa83964df33937967c75c644f
> > > >
> > > > since the /sys/devices/vio/uevent file has always returned ENODEV from
> > > > any write to it, this now causes the udevadm trigger command to return
> > > > an error. This may be fixed in udevadm to ignore ENODEV errors, but the
> > > > vio driver should still be fixed.
> > > >
> > > > This patch changes the arch/powerpc/platform/pseries/vio.c 'dummy'
> > > > parent device into a real dummy device with no .bus, so its uevent
> > > > file will stop returning ENODEV and simply do nothing and return 0.
> > > >
> > > > Signed-off-by: Dan Streetman
> > > > ---
> > > > arch/powerpc/platforms/pseries/vio.c | 11 ---
> > > > 1 file changed, 4 insertions(+), 7 deletions(-)
> > > >
> > > > diff --git a/arch/powerpc/platforms/pseries/vio.c
> > > > b/arch/powerpc/platforms/pseries/vio.c
> > > > index 79e2287991db..63bc16631680 100644
> > > > --- a/arch/powerpc/platforms/pseries/vio.c
> > > > +++ b/arch/powerpc/platforms/pseries/vio.c
> > > > @@ -32,11 +32,8 @@
> > > > #include
> > > > #include
> > > >
> > > > -static struct vio_dev vio_bus_device = { /* fake "parent" device */
> > > > - .name = "vio",
> > > > - .type = "",
> > > > - .dev.init_name = "vio",
> > > > - .dev.bus = _bus_type,
> > > > +static struct device vio_bus = {
> > > > + .init_name = "vio",
> > >
> > > Eeek, no! Why are you creating a static device that will then be
> > > reference counted? Not nice :(
> >
> > sorry! I'll admit that I simply copied what drivers/base/platform.c
> > seemed to be doing.
>
> I don't see platform.c having a 'static struct device' anywhere in it,
> am I missing it in my searching?
no, you are right, what I meant was:
struct device platform_bus = {
.init_name = "platform",
};
>
> thanks,
>
> greg k-h
Re: [PATCH] powerpc/vio: use simple dummy struct device as bus parent
On Fri, Sep 27, 2019 at 2:19 PM Greg Kroah-Hartman
wrote:
>
> On Fri, Sep 27, 2019 at 09:04:02AM -0400, Dan Streetman wrote:
> > The dummy vio_bus_device creates the /sys/devices/vio directory, which
> > contains real vio devices under it; since it represents itself as having
> > a bus = _bus_type, its /sys/devices/vio/uevent does call the bus's
> > .uevent function, vio_hotplug(), and as that function won't find a real
> > device for the dummy vio_dev, it will return -ENODEV.
> >
> > One of the main users of the uevent node is udevadm, e.g. when it is called
> > with 'udevadm trigger --devices'. Up until recently, it would ignore any
> > errors returned when writing to devices' uevent file, but it was recently
> > changed to start returning error if it gets an error writing to any uevent
> > file:
> > https://github.com/systemd/systemd/commit/97afc0351a96e0daa83964df33937967c75c644f
> >
> > since the /sys/devices/vio/uevent file has always returned ENODEV from
> > any write to it, this now causes the udevadm trigger command to return
> > an error. This may be fixed in udevadm to ignore ENODEV errors, but the
> > vio driver should still be fixed.
> >
> > This patch changes the arch/powerpc/platform/pseries/vio.c 'dummy'
> > parent device into a real dummy device with no .bus, so its uevent
> > file will stop returning ENODEV and simply do nothing and return 0.
> >
> > Signed-off-by: Dan Streetman
> > ---
> > arch/powerpc/platforms/pseries/vio.c | 11 ---
> > 1 file changed, 4 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/powerpc/platforms/pseries/vio.c
> > b/arch/powerpc/platforms/pseries/vio.c
> > index 79e2287991db..63bc16631680 100644
> > --- a/arch/powerpc/platforms/pseries/vio.c
> > +++ b/arch/powerpc/platforms/pseries/vio.c
> > @@ -32,11 +32,8 @@
> > #include
> > #include
> >
> > -static struct vio_dev vio_bus_device = { /* fake "parent" device */
> > - .name = "vio",
> > - .type = "",
> > - .dev.init_name = "vio",
> > - .dev.bus = _bus_type,
> > +static struct device vio_bus = {
> > + .init_name = "vio",
>
> Eeek, no! Why are you creating a static device that will then be
> reference counted? Not nice :(
sorry! I'll admit that I simply copied what drivers/base/platform.c
seemed to be doing.
>
> What's wrong with a simple call to device_create() for your "fake"
> device you want to make here? That's what it is there for :)
ack, will send a new patch using that. thanks!
>
> thanks,
>
> greg k-h
Re: [PATCH] powerpc/vio: use simple dummy struct device as bus parent
On Fri, Sep 27, 2019 at 03:48:49PM -0400, Dan Streetman wrote:
> On Fri, Sep 27, 2019 at 2:19 PM Greg Kroah-Hartman
> wrote:
> >
> > On Fri, Sep 27, 2019 at 09:04:02AM -0400, Dan Streetman wrote:
> > > The dummy vio_bus_device creates the /sys/devices/vio directory, which
> > > contains real vio devices under it; since it represents itself as having
> > > a bus = _bus_type, its /sys/devices/vio/uevent does call the bus's
> > > .uevent function, vio_hotplug(), and as that function won't find a real
> > > device for the dummy vio_dev, it will return -ENODEV.
> > >
> > > One of the main users of the uevent node is udevadm, e.g. when it is
> > > called
> > > with 'udevadm trigger --devices'. Up until recently, it would ignore any
> > > errors returned when writing to devices' uevent file, but it was recently
> > > changed to start returning error if it gets an error writing to any uevent
> > > file:
> > > https://github.com/systemd/systemd/commit/97afc0351a96e0daa83964df33937967c75c644f
> > >
> > > since the /sys/devices/vio/uevent file has always returned ENODEV from
> > > any write to it, this now causes the udevadm trigger command to return
> > > an error. This may be fixed in udevadm to ignore ENODEV errors, but the
> > > vio driver should still be fixed.
> > >
> > > This patch changes the arch/powerpc/platform/pseries/vio.c 'dummy'
> > > parent device into a real dummy device with no .bus, so its uevent
> > > file will stop returning ENODEV and simply do nothing and return 0.
> > >
> > > Signed-off-by: Dan Streetman
> > > ---
> > > arch/powerpc/platforms/pseries/vio.c | 11 ---
> > > 1 file changed, 4 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/arch/powerpc/platforms/pseries/vio.c
> > > b/arch/powerpc/platforms/pseries/vio.c
> > > index 79e2287991db..63bc16631680 100644
> > > --- a/arch/powerpc/platforms/pseries/vio.c
> > > +++ b/arch/powerpc/platforms/pseries/vio.c
> > > @@ -32,11 +32,8 @@
> > > #include
> > > #include
> > >
> > > -static struct vio_dev vio_bus_device = { /* fake "parent" device */
> > > - .name = "vio",
> > > - .type = "",
> > > - .dev.init_name = "vio",
> > > - .dev.bus = _bus_type,
> > > +static struct device vio_bus = {
> > > + .init_name = "vio",
> >
> > Eeek, no! Why are you creating a static device that will then be
> > reference counted? Not nice :(
>
> sorry! I'll admit that I simply copied what drivers/base/platform.c
> seemed to be doing.
I don't see platform.c having a 'static struct device' anywhere in it,
am I missing it in my searching?
thanks,
greg k-h
Re: [PATCH] powerpc/vio: use simple dummy struct device as bus parent
On Fri, Sep 27, 2019 at 09:04:02AM -0400, Dan Streetman wrote:
> The dummy vio_bus_device creates the /sys/devices/vio directory, which
> contains real vio devices under it; since it represents itself as having
> a bus = _bus_type, its /sys/devices/vio/uevent does call the bus's
> .uevent function, vio_hotplug(), and as that function won't find a real
> device for the dummy vio_dev, it will return -ENODEV.
>
> One of the main users of the uevent node is udevadm, e.g. when it is called
> with 'udevadm trigger --devices'. Up until recently, it would ignore any
> errors returned when writing to devices' uevent file, but it was recently
> changed to start returning error if it gets an error writing to any uevent
> file:
> https://github.com/systemd/systemd/commit/97afc0351a96e0daa83964df33937967c75c644f
>
> since the /sys/devices/vio/uevent file has always returned ENODEV from
> any write to it, this now causes the udevadm trigger command to return
> an error. This may be fixed in udevadm to ignore ENODEV errors, but the
> vio driver should still be fixed.
>
> This patch changes the arch/powerpc/platform/pseries/vio.c 'dummy'
> parent device into a real dummy device with no .bus, so its uevent
> file will stop returning ENODEV and simply do nothing and return 0.
>
> Signed-off-by: Dan Streetman
> ---
> arch/powerpc/platforms/pseries/vio.c | 11 ---
> 1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/vio.c
> b/arch/powerpc/platforms/pseries/vio.c
> index 79e2287991db..63bc16631680 100644
> --- a/arch/powerpc/platforms/pseries/vio.c
> +++ b/arch/powerpc/platforms/pseries/vio.c
> @@ -32,11 +32,8 @@
> #include
> #include
>
> -static struct vio_dev vio_bus_device = { /* fake "parent" device */
> - .name = "vio",
> - .type = "",
> - .dev.init_name = "vio",
> - .dev.bus = _bus_type,
> +static struct device vio_bus = {
> + .init_name = "vio",
Eeek, no! Why are you creating a static device that will then be
reference counted? Not nice :(
What's wrong with a simple call to device_create() for your "fake"
device you want to make here? That's what it is there for :)
thanks,
greg k-h
