Messages in this thread Patch in this message | | | Date | Wed, 31 May 2023 15:09:56 +0800 | Subject | Re: [PATCH 2/2] iommu/vt-d: Use BUG_ON to check NULL value of 'table' | From | Yanfei Xu <> |
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Hi Baolu,
On 5/31/2023 11:26 AM, Baolu Lu wrote: > On 5/30/23 5:25 PM, Yanfei Xu wrote: >> Checking NULL value of 'table' variable deserves a BUG_ON as the >> following code will trigger a crash by dereferencing the NULL >> 'table' pointer. Crash in advance with BUG_ON to avoid WARN_ON >> plus NULL pointer dereferencing can simplify the crash log. >> >> Signed-off-by: Yanfei Xu<yanfei.xu@intel.com> >> --- >> drivers/iommu/intel/iommu.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c >> index e98f1b122b49..8aa3bfdb7f95 100644 >> --- a/drivers/iommu/intel/iommu.c >> +++ b/drivers/iommu/intel/iommu.c >> @@ -1944,7 +1944,7 @@ static int domain_context_mapping_one(struct >> dmar_domain *domain, >> if (sm_supported(iommu)) { >> unsigned long pds; >> - WARN_ON(!table); >> + BUG_ON(!table); > > BUG_ON() is not recommended. Perhaps, > > if (!table) > -ENODEV; > Agree:) It is always better to handle the error than crash kernel.
How about: diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 8096273b034c..7f077e3a4128 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -1944,7 +1944,10 @@ static int domain_context_mapping_one(struct dmar_domain *domain, if (sm_supported(iommu)) { unsigned long pds;
- WARN_ON(!table); + if (WARN_ON(!table)) { + ret = -ENODEV; + goto out_unlock; + }
Thanks, Yanfei
> ? > > Best regards, > baolu
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