* [PATCH] tpm/ppi: replace assertion code with recovery in tpm_eval_dsm
@ 2019-12-15 18:23 Aditya Pakki
2019-12-17 11:06 ` Jarkko Sakkinen
2019-12-18 13:45 ` Jason Gunthorpe
0 siblings, 2 replies; 4+ messages in thread
From: Aditya Pakki @ 2019-12-15 18:23 UTC (permalink / raw)
To: pakki001
Cc: kjlu, Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe,
Arnd Bergmann, Greg Kroah-Hartman, linux-integrity, linux-kernel
In tpm_eval_dsm, BUG_ON on ppi_handle is used as an assertion.
By returning NULL to the callers, instead of crashing, the error
can be better handled.
Signed-off-by: Aditya Pakki <pakki001@umn.edu>
---
drivers/char/tpm/tpm_ppi.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
index b2dab941cb7f..4b6f6a9c0b48 100644
--- a/drivers/char/tpm/tpm_ppi.c
+++ b/drivers/char/tpm/tpm_ppi.c
@@ -42,7 +42,9 @@ static inline union acpi_object *
tpm_eval_dsm(acpi_handle ppi_handle, int func, acpi_object_type type,
union acpi_object *argv4, u64 rev)
{
- BUG_ON(!ppi_handle);
+ if (!ppi_handle)
+ return NULL;
+
return acpi_evaluate_dsm_typed(ppi_handle, &tpm_ppi_guid,
rev, func, argv4, type);
}
--
2.20.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] tpm/ppi: replace assertion code with recovery in tpm_eval_dsm
2019-12-15 18:23 [PATCH] tpm/ppi: replace assertion code with recovery in tpm_eval_dsm Aditya Pakki
@ 2019-12-17 11:06 ` Jarkko Sakkinen
2019-12-18 13:45 ` Jason Gunthorpe
1 sibling, 0 replies; 4+ messages in thread
From: Jarkko Sakkinen @ 2019-12-17 11:06 UTC (permalink / raw)
To: Aditya Pakki
Cc: kjlu, Peter Huewe, Jason Gunthorpe, Arnd Bergmann,
Greg Kroah-Hartman, linux-integrity, linux-kernel
On Sun, 2019-12-15 at 12:23 -0600, Aditya Pakki wrote:
> In tpm_eval_dsm, BUG_ON on ppi_handle is used as an assertion.
> By returning NULL to the callers, instead of crashing, the error
> can be better handled.
>
> Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Thanks.
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
/Jarkko
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] tpm/ppi: replace assertion code with recovery in tpm_eval_dsm
2019-12-15 18:23 [PATCH] tpm/ppi: replace assertion code with recovery in tpm_eval_dsm Aditya Pakki
2019-12-17 11:06 ` Jarkko Sakkinen
@ 2019-12-18 13:45 ` Jason Gunthorpe
2019-12-19 0:02 ` Jarkko Sakkinen
1 sibling, 1 reply; 4+ messages in thread
From: Jason Gunthorpe @ 2019-12-18 13:45 UTC (permalink / raw)
To: Aditya Pakki
Cc: kjlu, Peter Huewe, Jarkko Sakkinen, Arnd Bergmann,
Greg Kroah-Hartman, linux-integrity, linux-kernel
On Sun, Dec 15, 2019 at 12:23:14PM -0600, Aditya Pakki wrote:
> In tpm_eval_dsm, BUG_ON on ppi_handle is used as an assertion.
> By returning NULL to the callers, instead of crashing, the error
> can be better handled.
>
> Signed-off-by: Aditya Pakki <pakki001@umn.edu>
> drivers/char/tpm/tpm_ppi.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
> index b2dab941cb7f..4b6f6a9c0b48 100644
> +++ b/drivers/char/tpm/tpm_ppi.c
> @@ -42,7 +42,9 @@ static inline union acpi_object *
> tpm_eval_dsm(acpi_handle ppi_handle, int func, acpi_object_type type,
> union acpi_object *argv4, u64 rev)
> {
> - BUG_ON(!ppi_handle);
> + if (!ppi_handle)
> + return NULL;
If it can't happen the confusing if should either be omitted entirely
or written as
if (WARN_ON(!ppi_handle))
return NULL;
Leaving it as apparently operational code just creates confusion for
the reader that now has the task to figure out why ppi_handle can be
null.
I favour not including tests for impossible conditions. The kernel
will crash immediately if ppi_handle is null anyhow.
Jason
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] tpm/ppi: replace assertion code with recovery in tpm_eval_dsm
2019-12-18 13:45 ` Jason Gunthorpe
@ 2019-12-19 0:02 ` Jarkko Sakkinen
0 siblings, 0 replies; 4+ messages in thread
From: Jarkko Sakkinen @ 2019-12-19 0:02 UTC (permalink / raw)
To: Jason Gunthorpe, Aditya Pakki
Cc: kjlu, Peter Huewe, Arnd Bergmann, Greg Kroah-Hartman,
linux-integrity, linux-kernel
On Wed, 2019-12-18 at 09:45 -0400, Jason Gunthorpe wrote:
> On Sun, Dec 15, 2019 at 12:23:14PM -0600, Aditya Pakki wrote:
> > In tpm_eval_dsm, BUG_ON on ppi_handle is used as an assertion.
> > By returning NULL to the callers, instead of crashing, the error
> > can be better handled.
> >
> > Signed-off-by: Aditya Pakki <pakki001@umn.edu>
> > drivers/char/tpm/tpm_ppi.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
> > index b2dab941cb7f..4b6f6a9c0b48 100644
> > +++ b/drivers/char/tpm/tpm_ppi.c
> > @@ -42,7 +42,9 @@ static inline union acpi_object *
> > tpm_eval_dsm(acpi_handle ppi_handle, int func, acpi_object_type type,
> > union acpi_object *argv4, u64 rev)
> > {
> > - BUG_ON(!ppi_handle);
> > + if (!ppi_handle)
> > + return NULL;
>
> If it can't happen the confusing if should either be omitted entirely
> or written as
>
> if (WARN_ON(!ppi_handle))
> return NULL;
>
> Leaving it as apparently operational code just creates confusion for
> the reader that now has the task to figure out why ppi_handle can be
> null.
>
> I favour not including tests for impossible conditions. The kernel
> will crash immediately if ppi_handle is null anyhow.
>
> Jason
Absolutely should be changed WARN_ON() as it never should happen. I'll
update the patch before sending PR to Linus since I have it already
applied.
Thanks Jason for the remark!
/Jarkko
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-12-19 0:03 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2019-12-15 18:23 [PATCH] tpm/ppi: replace assertion code with recovery in tpm_eval_dsm Aditya Pakki
2019-12-17 11:06 ` Jarkko Sakkinen
2019-12-18 13:45 ` Jason Gunthorpe
2019-12-19 0:02 ` Jarkko Sakkinen
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