| Message ID | 1484154898-4342-1-git-send-email-jonathanh@nvidia.com |
|---|---|
| State | Superseded |
| Headers | show |
On 11/01/17 17:14, Jon Hunter wrote: > When regulators are successfully registered, we check to see if the > regulator is a supply for any other registered regulator and if so > add the new regulator as the supply for the existing regulator(s). > > Some devices, such as Power Management ICs, may register a series of > regulators when probed and there are cases where one of the regulators > may fail to register and defer the probing of the parent device. In this > case any successfully registered regulators would be unregistered so > that they can be re-registered at some time later when the probe is > attempted again. However, if one of the regulators that was registered > was added as a supply to another registered regulator (that did not > belong to the same parent device), then this supply regulator was > unregister again because the parent device is probe deferred, then a > regulator could be holding an invalid reference to a supply regulator > that has been unregistered. This will lead to a system crash if that > regulator is then used. > > Although it would be possible to check when unregistering a regulator > if any other regulator in the system is using it as a supply, it still > may not be possible to remove it as a supply if this other regulator is > in use. Therefore, fix this by preventing any regulator from adding > another regulator as a supply if the parent device for the supply > regulator has not been bound and if the parent device for the supply > and the regulator are different. This will allow a parent device that is > registering regulators to be probe deferred and ensure that none of the > regulators it has registered are used as supplies for any other > regulator from another device. > > Signed-off-by: Jon Hunter <jonathanh@nvidia.com> > --- > > Changes since V1: > - Updated patch per Mark's input to only prevent resolving the supply > if the supply's parent is different from the regulator's and the > supply's parent device is not bound. > - Added comment. > > drivers/regulator/core.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c > index 04baac9a165b..00466a82c3ad 100644 > --- a/drivers/regulator/core.c > +++ b/drivers/regulator/core.c > @@ -1553,6 +1553,19 @@ static int regulator_resolve_supply(struct regulator_dev *rdev) > } > } > > + /* > + * If the supply's parent device is not the same as the > + * regulator's parent device, then ensure the parent device > + * is bound before we resolve the supply, in case the parent > + * device get probe deferred and unregisters the supply. > + */ Ugh ... looks like I screwed up the formatting here. Also ... s/get/gets Resending ... Jon
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 04baac9a165b..00466a82c3ad 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -1553,6 +1553,19 @@ static int regulator_resolve_supply(struct regulator_dev *rdev) } } + /* + * If the supply's parent device is not the same as the + * regulator's parent device, then ensure the parent device + * is bound before we resolve the supply, in case the parent + * device get probe deferred and unregisters the supply. + */ + if (r->dev.parent && r->dev.parent != rdev->dev.parent) { + if (!device_is_bound(r->dev.parent)) { + put_device(&r->dev); + return -EPROBE_DEFER; + } + } + /* Recursively resolve the supply of the supply */ ret = regulator_resolve_supply(r); if (ret < 0) {
When regulators are successfully registered, we check to see if the regulator is a supply for any other registered regulator and if so add the new regulator as the supply for the existing regulator(s). Some devices, such as Power Management ICs, may register a series of regulators when probed and there are cases where one of the regulators may fail to register and defer the probing of the parent device. In this case any successfully registered regulators would be unregistered so that they can be re-registered at some time later when the probe is attempted again. However, if one of the regulators that was registered was added as a supply to another registered regulator (that did not belong to the same parent device), then this supply regulator was unregister again because the parent device is probe deferred, then a regulator could be holding an invalid reference to a supply regulator that has been unregistered. This will lead to a system crash if that regulator is then used. Although it would be possible to check when unregistering a regulator if any other regulator in the system is using it as a supply, it still may not be possible to remove it as a supply if this other regulator is in use. Therefore, fix this by preventing any regulator from adding another regulator as a supply if the parent device for the supply regulator has not been bound and if the parent device for the supply and the regulator are different. This will allow a parent device that is registering regulators to be probe deferred and ensure that none of the regulators it has registered are used as supplies for any other regulator from another device. Signed-off-by: Jon Hunter <jonathanh@nvidia.com> --- Changes since V1: - Updated patch per Mark's input to only prevent resolving the supply if the supply's parent is different from the regulator's and the supply's parent device is not bound. - Added comment. drivers/regulator/core.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)