Messages in this thread | | | Date | Fri, 5 Jun 2020 10:13:13 -0700 | From | Ira Weiny <> | Subject | Re: [PATCH v10 4/6] powerpc/papr_scm: Improve error logging and handling papr_scm_ndctl() |
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On Fri, Jun 05, 2020 at 05:11:34AM +0530, Vaibhav Jain wrote: > Since papr_scm_ndctl() can be called from outside papr_scm, its > exposed to the possibility of receiving NULL as value of 'cmd_rc' > argument. This patch updates papr_scm_ndctl() to protect against such > possibility by assigning it pointer to a local variable in case cmd_rc > == NULL. > > Finally the patch also updates the 'default' clause of the switch-case > block removing a 'return' statement thereby ensuring that value of > 'cmd_rc' is always logged when papr_scm_ndctl() returns. > > Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: Michael Ellerman <mpe@ellerman.id.au> > Cc: Ira Weiny <ira.weiny@intel.com> > Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com> > --- > Changelog: > > v9..v10 > * New patch in the series
Thanks for making this a separate patch it is easier to see what is going on here.
> --- > arch/powerpc/platforms/pseries/papr_scm.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c > index 0c091622b15e..6512fe6a2874 100644 > --- a/arch/powerpc/platforms/pseries/papr_scm.c > +++ b/arch/powerpc/platforms/pseries/papr_scm.c > @@ -355,11 +355,16 @@ static int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, > { > struct nd_cmd_get_config_size *get_size_hdr; > struct papr_scm_priv *p; > + int rc; > > /* Only dimm-specific calls are supported atm */ > if (!nvdimm) > return -EINVAL; > > + /* Use a local variable in case cmd_rc pointer is NULL */ > + if (!cmd_rc) > + cmd_rc = &rc; > +
This protects you from the NULL. However...
> p = nvdimm_provider_data(nvdimm); > > switch (cmd) { > @@ -381,12 +386,13 @@ static int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, > break; > > default: > - return -EINVAL; > + dev_dbg(&p->pdev->dev, "Unknown command = %d\n", cmd); > + *cmd_rc = -EINVAL;
... I think you are conflating rc and cmd_rc...
> } > > dev_dbg(&p->pdev->dev, "returned with cmd_rc = %d\n", *cmd_rc); > > - return 0; > + return *cmd_rc;
... this changes the behavior of the current commands. Now if the underlying papr_scm_meta_[get|set]() fails you return that failure as rc rather than 0.
Is that ok?
Also 'logging cmd_rc' in the invalid cmd case does not seem quite right unless you really want rc to be cmd_rc.
The architecture is designed to separate errors which occur in the kernel vs errors in the firmware/dimm. Are they always the same? The current code differentiates them.
Ira
> } > > static ssize_t flags_show(struct device *dev, > -- > 2.26.2 >
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