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SubjectRE: Clang warning in drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
Date
I am going to apply your fix patch in my branch.

Thanks
xinhui

-----Original Message-----
From: Nathan Chancellor <natechancellor@gmail.com>
Sent: 2019年3月20日 23:45
To: Stephen Hines <srhines@google.com>
Cc: Koenig, Christian <Christian.Koenig@amd.com>; Pan, Xinhui <Xinhui.Pan@amd.com>; Deucher, Alexander <Alexander.Deucher@amd.com>; Zhou, David(ChunMing) <David1.Zhou@amd.com>; amd-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org; clang-built-linux@googlegroups.com
Subject: Re: Clang warning in drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c

On Wed, Mar 20, 2019 at 07:58:09AM -0700, Stephen Hines wrote:
> Why are there 2 different enums for this same thing at all? By
> casting, you are reducing type safety in the kernel, which can cause
> bugs later (should the two enums diverge in encoding). In my opinion,
> the proper solution is to remove one of the enums or provide an
> explicit helper that does the conversion (along with assertions for
> handling any unexpected cases). The helper function should not be
> doing a direct cast, since a bug could change the integer value of one
> (or both) of these enums so that they don't match up.
>
> Thanks,
> Steve
>

Indeed, I would suggest something like this (if this was to be a build time error, this would need to be a macro instead of a function):

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
index a71668b8a7d0..451478cf4f35 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
@@ -541,13 +541,13 @@ int amdgpu_ras_feature_enable(struct amdgpu_device *adev,

if (!enable) {
info.disable_features = (struct ta_ras_disable_features_input) {
- .block_id = head->block,
- .error_type = head->type,
+ .block_id = amdgpu_ras_block_to_ta(head->block),
+ .error_type = amdgpu_ras_error_to_ta(head->type),
};
} else {
info.enable_features = (struct ta_ras_enable_features_input) {
- .block_id = head->block,
- .error_type = head->type,
+ .block_id = amdgpu_ras_block_to_ta(head->block),
+ .error_type = amdgpu_ras_error_to_ta(head->type),
};
}

@@ -647,8 +647,8 @@ int amdgpu_ras_error_inject(struct amdgpu_device *adev, {
struct ras_manager *obj = amdgpu_ras_find_obj(adev, &info->head);
struct ta_ras_trigger_error_input block_info = {
- .block_id = info->head.block,
- .inject_error_type = info->head.type,
+ .block_id = amdgpu_ras_block_to_ta(info->head.block),
+ .inject_error_type = amdgpu_ras_error_to_ta(info->head.type),
.sub_block_index = info->head.sub_block_index,
.address = info->address,
.value = info->value,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.h
index 7a35316baab0..c8576ab6e057 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.h
@@ -197,6 +197,64 @@ static inline int amdgpu_ras_reset_gpu(struct amdgpu_device *adev,
return 0;
}

+static inline enum ta_ras_block
+amdgpu_ras_block_to_ta(enum amdgpu_ras_block block) {
+ switch (block) {
+ case AMDGPU_RAS_BLOCK__UMC:
+ return TA_RAS_BLOCK__UMC;
+ case AMDGPU_RAS_BLOCK__SDMA:
+ return TA_RAS_BLOCK__SDMA;
+ case AMDGPU_RAS_BLOCK__GFX:
+ return TA_RAS_BLOCK__GFX;
+ case AMDGPU_RAS_BLOCK__MMHUB:
+ return TA_RAS_BLOCK__MMHUB;
+ case AMDGPU_RAS_BLOCK__ATHUB:
+ return TA_RAS_BLOCK__ATHUB;
+ case AMDGPU_RAS_BLOCK__PCIE_BIF:
+ return TA_RAS_BLOCK__PCIE_BIF;
+ case AMDGPU_RAS_BLOCK__HDP:
+ return TA_RAS_BLOCK__HDP;
+ case AMDGPU_RAS_BLOCK__XGMI_WAFL:
+ return TA_RAS_BLOCK__XGMI_WAFL;
+ case AMDGPU_RAS_BLOCK__DF:
+ return TA_RAS_BLOCK__DF;
+ case AMDGPU_RAS_BLOCK__SMN:
+ return TA_RAS_BLOCK__SMN;
+ case AMDGPU_RAS_BLOCK__SEM:
+ return TA_RAS_BLOCK__SEM;
+ case AMDGPU_RAS_BLOCK__MP0:
+ return TA_RAS_BLOCK__MP0;
+ case AMDGPU_RAS_BLOCK__MP1:
+ return TA_RAS_BLOCK__MP1;
+ case AMDGPU_RAS_BLOCK__FUSE:
+ return TA_RAS_BLOCK__FUSE;
+ default:
+ WARN(1, "amdgpu_ras_block_to_ta fell through with a value of %d\n", block);
+ return TA_RAS_BLOCK__UMC;
+ }
+}
+
+static inline enum ta_ras_error_type
+amdgpu_ras_error_to_ta(enum amdgpu_ras_error_type error) {
+ switch (error) {
+ case AMDGPU_RAS_ERROR__NONE:
+ return TA_RAS_ERROR__NONE;
+ case AMDGPU_RAS_ERROR__PARITY:
+ return TA_RAS_ERROR__PARITY;
+ case AMDGPU_RAS_ERROR__SINGLE_CORRECTABLE:
+ return TA_RAS_ERROR__SINGLE_CORRECTABLE;
+ case AMDGPU_RAS_ERROR__MULTI_UNCORRECTABLE:
+ return TA_RAS_ERROR__MULTI_UNCORRECTABLE;
+ case AMDGPU_RAS_ERROR__POISON:
+ return TA_RAS_ERROR__POISON;
+ default:
+ WARN(1, "amdgpu_ras_error_to_ta fell through with a value of %d\n", error);
+ return TA_RAS_ERROR__NONE;
+ }
+}
+
/* called in ip_init and ip_fini */
int amdgpu_ras_init(struct amdgpu_device *adev); void amdgpu_ras_post_init(struct amdgpu_device *adev);

> On Wed, Mar 20, 2019 at 2:37 AM Koenig, Christian
> <Christian.Koenig@amd.com>
> wrote:
>
> > Am 20.03.19 um 05:34 schrieb Nathan Chancellor:
> > > On Wed, Mar 20, 2019 at 01:31:27AM +0000, Pan, Xinhui wrote:
> > >> these two enumerated types are same for now. both of them might
> > >> change
> > in the future.
> > >>
> > >> I have not used clang, but would .block_id = (int)head->block
> > >> fix
> > your warning? If such change is acceptable, I can make one then.
> > >>
> > >> Thanks
> > >> xinhui
> > >>
> > >>
> > >> -----Original Message-----
> > >> From: Nathan Chancellor <natechancellor@gmail.com>
> > >> Sent: 2019年3月20日 8:54
> > >> To: Deucher, Alexander <Alexander.Deucher@amd.com>; Koenig,
> > >> Christian <
> > Christian.Koenig@amd.com>; Zhou, David(ChunMing)
> > <David1.Zhou@amd.com>; Pan, Xinhui <Xinhui.Pan@amd.com>
> > >> Cc: amd-gfx@lists.freedesktop.org;
> > >> dri-devel@lists.freedesktop.org;
> > linux-kernel@vger.kernel.org; clang-built-linux@googlegroups.com
> > >> Subject: Clang warning in drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> > >>
> > >> Hi all,
> > >>
> > >> The introduction of this file in commit dbd249c24427
> > >> ("drm/amdgpu: add
> > amdgpu_ras.c to support ras (v2)") introduces the following Clang
> > >> warnings:
> > >>
> > >> drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c:544:23: warning: implicit
> > conversion from enumeration type 'enum amdgpu_ras_block' to
> > different enumeration type 'enum ta_ras_block' [-Wenum-conversion]
> > >> .block_id = head->block,
> > >> ~~~~~~^~~~~
> > >> drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c:545:24: warning: implicit
> > conversion from enumeration type 'enum amdgpu_ras_error_type' to
> > different enumeration type 'enum ta_ras_error_type'
> > [-Wenum-conversion]
> > >> .error_type = head->type,
> > >> ~~~~~~^~~~
> > >> drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c:549:23: warning: implicit
> > conversion from enumeration type 'enum amdgpu_ras_block' to
> > different enumeration type 'enum ta_ras_block' [-Wenum-conversion]
> > >> .block_id = head->block,
> > >> ~~~~~~^~~~~
> > >> drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c:550:24: warning: implicit
> > conversion from enumeration type 'enum amdgpu_ras_error_type' to
> > different enumeration type 'enum ta_ras_error_type'
> > [-Wenum-conversion]
> > >> .error_type = head->type,
> > >> ~~~~~~^~~~
> > >> drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c:650:26: warning: implicit
> > conversion from enumeration type 'enum amdgpu_ras_block' to
> > different enumeration type 'enum ta_ras_block' [-Wenum-conversion]
> > >> .block_id = info->head.block,
> > >> ~~~~~~~~~~~^~~~~
> > >> drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c:651:35: warning: implicit
> > conversion from enumeration type 'enum amdgpu_ras_error_type' to
> > different enumeration type 'enum ta_ras_error_type'
> > [-Wenum-conversion]
> > >> .inject_error_type = info->head.type,
> > >> ~~~~~~~~~~~^~~~
> > >> 6 warnings generated.
> > >>
> > >> Normally, I would sent a fix for this myself but I am not
> > >> entirely sure
> > why these two enumerated types exist when one would do since they
> > have the same values minus the prefix. In fact, the
> > ta_ras_{block,error_type} values are never used aside from being
> > defined. Some clarification would be appreciated.
> > >>
> > >> Thank you,
> > >> Nathan
> > > Hi Xinhui,
> > >
> > > Yes, explicitly casting these six spots to int would resolve this
> > > warning.
> >
> > Another question is if it is such a good idea to just silence the warning?
> >
> > Maybe add a amdgpu_ras_error_to_ta() helper to do this casting?
> >
> > When the enums drift away from each other then we can still add
> > warnings to that helper to make sure we don't accidentally cast
> > invalid values around.
> >
> > Regards,
> > Christian.
> >
> > >
> > > Thank you for the quick response!
> > > Nathan
> >
> > --
> > You received this message because you are subscribed to the Google
> > Groups "Clang Built Linux" group.
> > To unsubscribe from this group and stop receiving emails from it,
> > send an email to clang-built-linux+unsubscribe@googlegroups.com.
> > To post to this group, send email to clang-built-linux@googlegroups.com.
> > To view this discussion on the web visit
> > https://groups.google.com/d/msgid/clang-built-linux/63518f1f-b808-77
> > b0-aac6-ee1ece669c4b%40amd.com
> > .
> > For more options, visit https://groups.google.com/d/optout.
> >
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