| Message ID | 20180712080623.21203-1-benjamin.gaignard@st.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | base: core: Remove WARN_ON from link dependencies check | expand |
On Thu, Jul 12, 2018 at 10:06:23AM +0200, Benjamin Gaignard wrote: > In some cases the link between between customer and supplier > already exist. Do not warn about already existing dependencies > because device_link_add() take care of this case. Why would a link already exist that is asked to be created again? What code path causes this? > > Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com> > --- > drivers/base/core.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index df3e1a44707a..fcdc17f0f349 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -105,7 +105,7 @@ static int device_is_dependent(struct device *dev, void *target) > struct device_link *link; > int ret; > > - if (WARN_ON(dev == target)) > + if (dev == target) > return 1; > > ret = device_for_each_child(dev, target, device_is_dependent); > @@ -113,7 +113,7 @@ static int device_is_dependent(struct device *dev, void *target) > return ret; > > list_for_each_entry(link, &dev->links.consumers, s_node) { > - if (WARN_ON(link->consumer == target)) > + if (link->consumer == target) > return 1; Both of these WARN_ON are for valid code? That feels really odd to me, I need more explanation here please. thanks, greg k-h
2018-07-12 10:55 GMT+02:00 Greg KH <gregkh@linuxfoundation.org>: > On Thu, Jul 12, 2018 at 10:06:23AM +0200, Benjamin Gaignard wrote: >> In some cases the link between between customer and supplier >> already exist. Do not warn about already existing dependencies >> because device_link_add() take care of this case. > > Why would a link already exist that is asked to be created again? What > code path causes this? It could happen that the link exist because a device use it parent as supplier. That case has been describe by Marek in this thread (I forgot to add it in the commit message, sorry): https://lkml.org/lkml/2018/7/9/356 > >> >> Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> >> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com> >> --- >> drivers/base/core.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/base/core.c b/drivers/base/core.c >> index df3e1a44707a..fcdc17f0f349 100644 >> --- a/drivers/base/core.c >> +++ b/drivers/base/core.c >> @@ -105,7 +105,7 @@ static int device_is_dependent(struct device *dev, void *target) >> struct device_link *link; >> int ret; >> >> - if (WARN_ON(dev == target)) >> + if (dev == target) >> return 1; >> >> ret = device_for_each_child(dev, target, device_is_dependent); >> @@ -113,7 +113,7 @@ static int device_is_dependent(struct device *dev, void *target) >> return ret; >> >> list_for_each_entry(link, &dev->links.consumers, s_node) { >> - if (WARN_ON(link->consumer == target)) >> + if (link->consumer == target) >> return 1; > > Both of these WARN_ON are for valid code? That feels really odd to me, > I need more explanation here please. The documentation of the function is clear about return values: "Check if @target depends on @dev or any device dependent on it (its child or ts consumer etc). Return 1 if that is the case or 0 otherwise." so, for me, not need to warn user about something that is expected. Benjamin > > thanks, > > greg k-h
On Thu, Jul 12, 2018 at 11:18:26AM +0200, Benjamin Gaignard wrote: > 2018-07-12 10:55 GMT+02:00 Greg KH <gregkh@linuxfoundation.org>: > > Why would a link already exist that is asked to be created again? What > > code path causes this? > It could happen that the link exist because a device use it parent as supplier. > That case has been describe by Marek in this thread (I forgot to add > it in the commit message, sorry): > https://lkml.org/lkml/2018/7/9/356 If we don't remove the warning then we'd need to have some way for generic code to check if a link that it wants to create exists already since if more than one thing adds links there's always a chance that two of them will come up with the same idea for a link. We could export device_is_dependent() and have them check that, or add a new flag that skips the check for example. This is however probably going to affect a reasonable percentage of potential users.
On Thu, Jul 12, 2018 at 10:06:23AM +0200, Benjamin Gaignard wrote: > In some cases the link between between customer and supplier > already exist. Do not warn about already existing dependencies > because device_link_add() take care of this case. Reviwed-by: Mark Brown <broonie@kernel.org>
On Thursday, July 12, 2018 11:18:26 AM CEST Benjamin Gaignard wrote: > 2018-07-12 10:55 GMT+02:00 Greg KH <gregkh@linuxfoundation.org>: > > On Thu, Jul 12, 2018 at 10:06:23AM +0200, Benjamin Gaignard wrote: > >> In some cases the link between between customer and supplier > >> already exist. Do not warn about already existing dependencies > >> because device_link_add() take care of this case. > > > > Why would a link already exist that is asked to be created again? What > > code path causes this? > > It could happen that the link exist because a device use it parent as supplier. > That case has been describe by Marek in this thread (I forgot to add > it in the commit message, sorry): > https://lkml.org/lkml/2018/7/9/356 So please add this information to the patch changelog and resend. Thanks, Rafael
diff --git a/drivers/base/core.c b/drivers/base/core.c index df3e1a44707a..fcdc17f0f349 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -105,7 +105,7 @@ static int device_is_dependent(struct device *dev, void *target) struct device_link *link; int ret; - if (WARN_ON(dev == target)) + if (dev == target) return 1; ret = device_for_each_child(dev, target, device_is_dependent); @@ -113,7 +113,7 @@ static int device_is_dependent(struct device *dev, void *target) return ret; list_for_each_entry(link, &dev->links.consumers, s_node) { - if (WARN_ON(link->consumer == target)) + if (link->consumer == target) return 1; ret = device_is_dependent(link->consumer, target);
In some cases the link between between customer and supplier already exist. Do not warn about already existing dependencies because device_link_add() take care of this case. Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com> --- drivers/base/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) -- 2.15.0