Messages in this thread Patch in this message | | | Date | Thu, 1 Jun 2023 09:15:37 +0800 | Subject | Re: [PATCH 1/2] iommu/vt-d: Remove the dead code in init_iommu_hw() | From | Baolu Lu <> |
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On 5/31/23 2:55 PM, Yanfei Xu wrote: > > On 5/31/2023 11:24 AM, Baolu Lu wrote: >> On 5/30/23 5:25 PM, Yanfei Xu wrote: >>> After 'commit 2a41ccee2fdc ("iommu/vt-d: Change >>> iommu_enable/disable_translation to return void")', init_iommu_hw() only >>> returns 0. If statement for return value of this function is >>> meaningless. >>> Hence change init_iommu_hw() to return viod and remove the dead code of >>> if statement in init_iommu_hw() >>> >>> Signed-off-by: Yanfei Xu<yanfei.xu@intel.com> >>> --- >>> drivers/iommu/intel/iommu.c | 12 ++---------- >>> 1 file changed, 2 insertions(+), 10 deletions(-) >>> >>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c >>> index 8096273b034c..e98f1b122b49 100644 >>> --- a/drivers/iommu/intel/iommu.c >>> +++ b/drivers/iommu/intel/iommu.c >>> @@ -2963,7 +2963,7 @@ static void __init init_no_remapping_devices(void) >>> } >>> #ifdef CONFIG_SUSPEND >>> -static int init_iommu_hw(void) >>> +static void init_iommu_hw(void) >>> { >>> struct dmar_drhd_unit *drhd; >>> struct intel_iommu *iommu = NULL; >>> @@ -2988,8 +2988,6 @@ static int init_iommu_hw(void) >>> iommu_enable_translation(iommu); >>> iommu_disable_protect_mem_regions(iommu); >>> } >>> - >>> - return 0; >> >> 2966 static int init_iommu_hw(void) >> 2967 { >> 2968 struct dmar_drhd_unit *drhd; >> 2969 struct intel_iommu *iommu = NULL; >> 2970 >> 2971 for_each_active_iommu(iommu, drhd) >> 2972 if (iommu->qi) >> 2973 dmar_reenable_qi(iommu); >> >> dmar_reenable_qi() still possibly returns an error number. It's better >> to pass this error number to the caller of init_iommu_hw()? >> > Event dmar_reenable_qi can return error number, but there is no caller > check it. As below, only these two places invoke it: > 1. init_iommu_hw->dmar_reenable_qi > 2. reenable_irq_remapping->dmar_reenable_qi > > I think we can also convert dmar_reenable_qi() to return void: > diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c > index a3414afe11b0..1432483c79e8 100644 > --- a/drivers/iommu/intel/dmar.c > +++ b/drivers/iommu/intel/dmar.c > @@ -2112,13 +2112,10 @@ int __init enable_drhd_fault_handling(void) > /* > * Re-enable Queued Invalidation interface. > */ > -int dmar_reenable_qi(struct intel_iommu *iommu) > +void dmar_reenable_qi(struct intel_iommu *iommu) > { > - if (!ecap_qis(iommu->ecap)) > - return -ENOENT; > - > - if (!iommu->qi) > - return -ENOENT; > + WARN_ON(!iommu->qi || !ecap_qis(iommu->ecap)) > + return; > > /* > * First disable queued invalidation. > @@ -2130,8 +2127,6 @@ int dmar_reenable_qi(struct intel_iommu *iommu) > * invalidation. > */ > __dmar_enable_qi(iommu); > - > - return 0; > } > > From my understanding, dmar_reenable_qi() is used in suspend/resume case, > so the extended cap of an existing IOMMU hardware is unlikely changed. As > for the check of iommu->qi, if dmar_reenable_qi() can be invoked all is > depended on the no-NULL of iommu->qi at first. How about using WARN_ON for > both of them to simply this function.
This seems to be heading in the opposite direction. Actually any operation may succeed or fail.
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index b871a6afd803..ecc2007a96f9 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -2967,10 +2967,13 @@ static int init_iommu_hw(void) { struct dmar_drhd_unit *drhd; struct intel_iommu *iommu = NULL; + int ret;
- for_each_active_iommu(iommu, drhd) - if (iommu->qi) - dmar_reenable_qi(iommu); + for_each_active_iommu(iommu, drhd) { + ret = dmar_reenable_qi(iommu); + if (ret) + return ret; + }
for_each_iommu(iommu, drhd) { if (drhd->ignored) { Best regards, baolu
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