| Message ID | 17705994.d592GUb2YH@kreacher |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] driver core: Extend device_is_dependent() | expand |
On Fri, Jan 15, 2021 at 10:30 AM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > If the device passed as the target (second argument) to > device_is_dependent() is not completely registered (that is, it has > been initialized, but not added yet), but the parent pointer of it > is set, it may be missing from the list of the parent's children > and device_for_each_child() called by device_is_dependent() cannot > be relied on to catch that dependency. > > For this reason, modify device_is_dependent() to check the ancestors > of the target device by following its parent pointer in addition to > the device_for_each_child() walk. > > Fixes: 9ed9895370ae ("driver core: Functional dependencies tracking support") > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > Reported-by: Stephan Gerhold <stephan@gerhold.net> > Tested-by: Stephan Gerhold <stephan@gerhold.net> > --- > > -> v2: > * Improve the changelog. > * Add a comment to explain the reason for the extra check. > * Add tags. > > No code changes. > > --- > drivers/base/core.c | 17 ++++++++++++++++- > 1 file changed, 16 insertions(+), 1 deletion(-) > > Index: linux-pm/drivers/base/core.c > =================================================================== > --- linux-pm.orig/drivers/base/core.c > +++ linux-pm/drivers/base/core.c > @@ -208,6 +208,16 @@ int device_links_read_lock_held(void) > #endif > #endif /* !CONFIG_SRCU */ > > +static bool device_is_ancestor(struct device *dev, struct device *target) > +{ > + while (target->parent) { > + target = target->parent; > + if (dev == target) > + return true; > + } > + return false; > +} > + > /** > * device_is_dependent - Check if one device depends on another one > * @dev: Device to check dependencies for. > @@ -221,7 +231,12 @@ int device_is_dependent(struct device *d > struct device_link *link; > int ret; > > - if (dev == target) > + /* > + * The "ancestors" check is needed to catch the case when the target > + * device has not been completely initialized yet and it is still > + * missing from the list of children of its parent device. > + */ > + if (dev == target || device_is_ancestor(dev, target)) > return 1; > > ret = device_for_each_child(dev, target, device_is_dependent); > Reviewed-by: Saravana Kannan <saravanak@google.com> fw_devlink_relax_cycle() needs a similar fix. Want me to handle that as a separate patch to driver-core-next? Or do you want to combine that in this patch? -Saravana
On Mon, Jan 18, 2021 at 11:03 PM Saravana Kannan <saravanak@google.com> wrote: > > On Fri, Jan 15, 2021 at 10:30 AM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > > > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > If the device passed as the target (second argument) to > > device_is_dependent() is not completely registered (that is, it has > > been initialized, but not added yet), but the parent pointer of it > > is set, it may be missing from the list of the parent's children > > and device_for_each_child() called by device_is_dependent() cannot > > be relied on to catch that dependency. > > > > For this reason, modify device_is_dependent() to check the ancestors > > of the target device by following its parent pointer in addition to > > the device_for_each_child() walk. > > > > Fixes: 9ed9895370ae ("driver core: Functional dependencies tracking support") > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > Reported-by: Stephan Gerhold <stephan@gerhold.net> > > Tested-by: Stephan Gerhold <stephan@gerhold.net> > > --- > > > > -> v2: > > * Improve the changelog. > > * Add a comment to explain the reason for the extra check. > > * Add tags. > > > > No code changes. > > > > --- > > drivers/base/core.c | 17 ++++++++++++++++- > > 1 file changed, 16 insertions(+), 1 deletion(-) > > > > Index: linux-pm/drivers/base/core.c > > =================================================================== > > --- linux-pm.orig/drivers/base/core.c > > +++ linux-pm/drivers/base/core.c > > @@ -208,6 +208,16 @@ int device_links_read_lock_held(void) > > #endif > > #endif /* !CONFIG_SRCU */ > > > > +static bool device_is_ancestor(struct device *dev, struct device *target) > > +{ > > + while (target->parent) { > > + target = target->parent; > > + if (dev == target) > > + return true; > > + } > > + return false; > > +} > > + > > /** > > * device_is_dependent - Check if one device depends on another one > > * @dev: Device to check dependencies for. > > @@ -221,7 +231,12 @@ int device_is_dependent(struct device *d > > struct device_link *link; > > int ret; > > > > - if (dev == target) > > + /* > > + * The "ancestors" check is needed to catch the case when the target > > + * device has not been completely initialized yet and it is still > > + * missing from the list of children of its parent device. > > + */ > > + if (dev == target || device_is_ancestor(dev, target)) > > return 1; > > > > ret = device_for_each_child(dev, target, device_is_dependent); > > > > Reviewed-by: Saravana Kannan <saravanak@google.com> > > fw_devlink_relax_cycle() needs a similar fix. Want me to handle that > as a separate patch to driver-core-next? Or do you want to combine > that in this patch? I would prefer that to be a different patch because of the Fixes: tag. Also fw_devlink_relax_cycle() is in linux-next only for now, so it is better to avoid mixing a mainline fix with updating that one.
On Fri, Jan 15, 2021 at 7:31 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > If the device passed as the target (second argument) to > device_is_dependent() is not completely registered (that is, it has > been initialized, but not added yet), but the parent pointer of it > is set, it may be missing from the list of the parent's children > and device_for_each_child() called by device_is_dependent() cannot > be relied on to catch that dependency. > > For this reason, modify device_is_dependent() to check the ancestors > of the target device by following its parent pointer in addition to > the device_for_each_child() walk. > > Fixes: 9ed9895370ae ("driver core: Functional dependencies tracking support") > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > Reported-by: Stephan Gerhold <stephan@gerhold.net> > Tested-by: Stephan Gerhold <stephan@gerhold.net> Greg, are you going to pick up this one or do you want me to take care of it? It has been reviewed by Saravana. > --- > > -> v2: > * Improve the changelog. > * Add a comment to explain the reason for the extra check. > * Add tags. > > No code changes. > > --- > drivers/base/core.c | 17 ++++++++++++++++- > 1 file changed, 16 insertions(+), 1 deletion(-) > > Index: linux-pm/drivers/base/core.c > =================================================================== > --- linux-pm.orig/drivers/base/core.c > +++ linux-pm/drivers/base/core.c > @@ -208,6 +208,16 @@ int device_links_read_lock_held(void) > #endif > #endif /* !CONFIG_SRCU */ > > +static bool device_is_ancestor(struct device *dev, struct device *target) > +{ > + while (target->parent) { > + target = target->parent; > + if (dev == target) > + return true; > + } > + return false; > +} > + > /** > * device_is_dependent - Check if one device depends on another one > * @dev: Device to check dependencies for. > @@ -221,7 +231,12 @@ int device_is_dependent(struct device *d > struct device_link *link; > int ret; > > - if (dev == target) > + /* > + * The "ancestors" check is needed to catch the case when the target > + * device has not been completely initialized yet and it is still > + * missing from the list of children of its parent device. > + */ > + if (dev == target || device_is_ancestor(dev, target)) > return 1; > > ret = device_for_each_child(dev, target, device_is_dependent); > > >
On Tue, Jan 19, 2021 at 04:09:14PM +0100, Rafael J. Wysocki wrote: > On Fri, Jan 15, 2021 at 7:31 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > > > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > If the device passed as the target (second argument) to > > device_is_dependent() is not completely registered (that is, it has > > been initialized, but not added yet), but the parent pointer of it > > is set, it may be missing from the list of the parent's children > > and device_for_each_child() called by device_is_dependent() cannot > > be relied on to catch that dependency. > > > > For this reason, modify device_is_dependent() to check the ancestors > > of the target device by following its parent pointer in addition to > > the device_for_each_child() walk. > > > > Fixes: 9ed9895370ae ("driver core: Functional dependencies tracking support") > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > Reported-by: Stephan Gerhold <stephan@gerhold.net> > > Tested-by: Stephan Gerhold <stephan@gerhold.net> > > Greg, are you going to pick up this one or do you want me to take care of it? > > It has been reviewed by Saravana. I'll take it, thanks. sorry for the delay. greg k-h
Index: linux-pm/drivers/base/core.c =================================================================== --- linux-pm.orig/drivers/base/core.c +++ linux-pm/drivers/base/core.c @@ -208,6 +208,16 @@ int device_links_read_lock_held(void) #endif #endif /* !CONFIG_SRCU */ +static bool device_is_ancestor(struct device *dev, struct device *target) +{ + while (target->parent) { + target = target->parent; + if (dev == target) + return true; + } + return false; +} + /** * device_is_dependent - Check if one device depends on another one * @dev: Device to check dependencies for. @@ -221,7 +231,12 @@ int device_is_dependent(struct device *d struct device_link *link; int ret; - if (dev == target) + /* + * The "ancestors" check is needed to catch the case when the target + * device has not been completely initialized yet and it is still + * missing from the list of children of its parent device. + */ + if (dev == target || device_is_ancestor(dev, target)) return 1; ret = device_for_each_child(dev, target, device_is_dependent);