| Message ID | 20170522103730.GB7553@red-moon (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
Hi Lorenzo, On 5/22/2017 4:07 PM, Lorenzo Pieralisi wrote: > Hi Sricharan, > > On Thu, May 18, 2017 at 08:24:16PM +0530, Sricharan R wrote: >> While deferring the probe of IOMMU masters, xlate and >> add_device callbacks called from iort_iommu_configure >> can pass back error values like -ENODEV, which means >> the IOMMU cannot be connected with that master for real >> reasons. Before the IOMMU probe deferral, all such errors >> were ignored. Now all those errors are propagated back, >> killing the master's probe for such errors. Instead ignore >> all the errors except EPROBE_DEFER, which is the only one >> of concern and let the master work without IOMMU, thus >> restoring the old behavior. >> >> Fixes: 5a1bb638d567 ("drivers: acpi: Handle IOMMU lookup failure with deferred probing or error") >> Signed-off-by: Sricharan R <sricharan@codeaurora.org> >> --- >> [V4] Added this patch newly. >> >> drivers/acpi/arm64/iort.c | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c >> index c5fecf9..16e101f 100644 >> --- a/drivers/acpi/arm64/iort.c >> +++ b/drivers/acpi/arm64/iort.c >> @@ -782,6 +782,12 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev) >> if (err) >> ops = ERR_PTR(err); >> >> + /* Ignore all other errors apart from EPROBE_DEFER */ >> + if (IS_ERR(ops) && (PTR_ERR(ops) != -EPROBE_DEFER)) { >> + dev_dbg(dev, "Adding to IOMMU failed: %ld\n", PTR_ERR(ops)); >> + ops = NULL; >> + } >> + >> return ops; >> } >> > > It is getting a bit convoluted. Is not it better to propagate the > error back and let acpi_dma_configure() make a decision accordingly ? > ok, I was trying to keep it in same way as DT, where of_dma_configure (here acpi_dma_configure) calls of_iommu_configure(here iort_iommu_configure) which ends up doing the check. So will have to be changed in both places for symmetry. > Something like: > > -- >8 -- > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index e39ec7b..3a10d757 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -1371,8 +1371,8 @@ int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr) > iort_set_dma_mask(dev); > > iommu = iort_iommu_configure(dev); > - if (IS_ERR(iommu)) > - return PTR_ERR(iommu); > + if (IS_ERR(iommu) && PTR_ERR(iommu) == -EPROBE_DEFER) > + return -EPROBE_DEFER; In case of other errors apart from EPROBE_DEFER, iommu = NULL should be set, before passing it on to arch_setup_dma_ops. Regards, Sricharan > > size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1); > /* >
On Mon, May 22, 2017 at 04:35:43PM +0530, Sricharan R wrote: > Hi Lorenzo, > > On 5/22/2017 4:07 PM, Lorenzo Pieralisi wrote: > > Hi Sricharan, > > > > On Thu, May 18, 2017 at 08:24:16PM +0530, Sricharan R wrote: > >> While deferring the probe of IOMMU masters, xlate and > >> add_device callbacks called from iort_iommu_configure > >> can pass back error values like -ENODEV, which means > >> the IOMMU cannot be connected with that master for real > >> reasons. Before the IOMMU probe deferral, all such errors > >> were ignored. Now all those errors are propagated back, > >> killing the master's probe for such errors. Instead ignore > >> all the errors except EPROBE_DEFER, which is the only one > >> of concern and let the master work without IOMMU, thus > >> restoring the old behavior. > >> > >> Fixes: 5a1bb638d567 ("drivers: acpi: Handle IOMMU lookup failure with deferred probing or error") > >> Signed-off-by: Sricharan R <sricharan@codeaurora.org> > >> --- > >> [V4] Added this patch newly. > >> > >> drivers/acpi/arm64/iort.c | 6 ++++++ > >> 1 file changed, 6 insertions(+) > >> > >> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c > >> index c5fecf9..16e101f 100644 > >> --- a/drivers/acpi/arm64/iort.c > >> +++ b/drivers/acpi/arm64/iort.c > >> @@ -782,6 +782,12 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev) > >> if (err) > >> ops = ERR_PTR(err); > >> > >> + /* Ignore all other errors apart from EPROBE_DEFER */ > >> + if (IS_ERR(ops) && (PTR_ERR(ops) != -EPROBE_DEFER)) { > >> + dev_dbg(dev, "Adding to IOMMU failed: %ld\n", PTR_ERR(ops)); > >> + ops = NULL; > >> + } > >> + > >> return ops; > >> } > >> > > > > It is getting a bit convoluted. Is not it better to propagate the > > error back and let acpi_dma_configure() make a decision accordingly ? > > > > ok, I was trying to keep it in same way as DT, where of_dma_configure > (here acpi_dma_configure) calls of_iommu_configure(here iort_iommu_configure) > which ends up doing the check. So will have to be changed in both places > for symmetry. > > > Something like: > > > > -- >8 -- > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > > index e39ec7b..3a10d757 100644 > > --- a/drivers/acpi/scan.c > > +++ b/drivers/acpi/scan.c > > @@ -1371,8 +1371,8 @@ int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr) > > iort_set_dma_mask(dev); > > > > iommu = iort_iommu_configure(dev); > > - if (IS_ERR(iommu)) > > - return PTR_ERR(iommu); > > + if (IS_ERR(iommu) && PTR_ERR(iommu) == -EPROBE_DEFER) > > + return -EPROBE_DEFER; > > In case of other errors apart from EPROBE_DEFER, > iommu = NULL should be set, before passing it on to > arch_setup_dma_ops. Ah yes, sorry, that makes it uglier :( Point is, it does not make sense to me to have of/acpi_dma_configure() check a return code with (IS_ERR()) whilst we know the only error code you are allowed to handle is -EPROBE_DEFER, while at it it is better to make the -EPROBE_DEFER check explicit (otherwise it may seem that of/acpi_dma_configure() can handle an error code that is different from -EPROBE_DEFER - but they don't), no big deal either way though. Lorenzo
Hi Lorenzo, On 5/22/2017 5:01 PM, Lorenzo Pieralisi wrote: > On Mon, May 22, 2017 at 04:35:43PM +0530, Sricharan R wrote: >> Hi Lorenzo, >> >> On 5/22/2017 4:07 PM, Lorenzo Pieralisi wrote: >>> Hi Sricharan, >>> >>> On Thu, May 18, 2017 at 08:24:16PM +0530, Sricharan R wrote: >>>> While deferring the probe of IOMMU masters, xlate and >>>> add_device callbacks called from iort_iommu_configure >>>> can pass back error values like -ENODEV, which means >>>> the IOMMU cannot be connected with that master for real >>>> reasons. Before the IOMMU probe deferral, all such errors >>>> were ignored. Now all those errors are propagated back, >>>> killing the master's probe for such errors. Instead ignore >>>> all the errors except EPROBE_DEFER, which is the only one >>>> of concern and let the master work without IOMMU, thus >>>> restoring the old behavior. >>>> >>>> Fixes: 5a1bb638d567 ("drivers: acpi: Handle IOMMU lookup failure with deferred probing or error") >>>> Signed-off-by: Sricharan R <sricharan@codeaurora.org> >>>> --- >>>> [V4] Added this patch newly. >>>> >>>> drivers/acpi/arm64/iort.c | 6 ++++++ >>>> 1 file changed, 6 insertions(+) >>>> >>>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c >>>> index c5fecf9..16e101f 100644 >>>> --- a/drivers/acpi/arm64/iort.c >>>> +++ b/drivers/acpi/arm64/iort.c >>>> @@ -782,6 +782,12 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev) >>>> if (err) >>>> ops = ERR_PTR(err); >>>> >>>> + /* Ignore all other errors apart from EPROBE_DEFER */ >>>> + if (IS_ERR(ops) && (PTR_ERR(ops) != -EPROBE_DEFER)) { >>>> + dev_dbg(dev, "Adding to IOMMU failed: %ld\n", PTR_ERR(ops)); >>>> + ops = NULL; >>>> + } >>>> + >>>> return ops; >>>> } >>>> >>> >>> It is getting a bit convoluted. Is not it better to propagate the >>> error back and let acpi_dma_configure() make a decision accordingly ? >>> >> >> ok, I was trying to keep it in same way as DT, where of_dma_configure >> (here acpi_dma_configure) calls of_iommu_configure(here iort_iommu_configure) >> which ends up doing the check. So will have to be changed in both places >> for symmetry. >> >>> Something like: >>> >>> -- >8 -- >>> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c >>> index e39ec7b..3a10d757 100644 >>> --- a/drivers/acpi/scan.c >>> +++ b/drivers/acpi/scan.c >>> @@ -1371,8 +1371,8 @@ int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr) >>> iort_set_dma_mask(dev); >>> >>> iommu = iort_iommu_configure(dev); >>> - if (IS_ERR(iommu)) >>> - return PTR_ERR(iommu); >>> + if (IS_ERR(iommu) && PTR_ERR(iommu) == -EPROBE_DEFER) >>> + return -EPROBE_DEFER; >> >> In case of other errors apart from EPROBE_DEFER, >> iommu = NULL should be set, before passing it on to >> arch_setup_dma_ops. > > Ah yes, sorry, that makes it uglier :( > > Point is, it does not make sense to me to have of/acpi_dma_configure() > check a return code with (IS_ERR()) whilst we know the only error > code you are allowed to handle is -EPROBE_DEFER, while at it it is > better to make the -EPROBE_DEFER check explicit (otherwise it may > seem that of/acpi_dma_configure() can handle an error code that > is different from -EPROBE_DEFER - but they don't), no big deal either > way though. > ok, in which case, the above check that you have shown to be added additionally to the original patch. Regards, Sricharan
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index e39ec7b..3a10d757 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -1371,8 +1371,8 @@ int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr) iort_set_dma_mask(dev); iommu = iort_iommu_configure(dev); - if (IS_ERR(iommu)) - return PTR_ERR(iommu); + if (IS_ERR(iommu) && PTR_ERR(iommu) == -EPROBE_DEFER) + return -EPROBE_DEFER; size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1); /*