intel-iommu: fault_reason index cleanup

Fix an off by one bug in the fault reason string reporting function, and
clean up some of the code around this buglet.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: mark gross <mgross@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 6 insertions, 7 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 585e188c1746..a4c3089f892a 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -745,7 +745,7 @@ static int iommu_disable_translation(struct intel_iommu *iommu)
 
 /* iommu interrupt handling. Most stuff are MSI-like. */
 
-static char *fault_reason_strings[] =
+static const char *fault_reason_strings[] =
 {
         "Software",
         "Present bit in root entry is clear",
@@ -760,14 +760,13 @@ static char *fault_reason_strings[] =
         "non-zero reserved fields in RTP",
         "non-zero reserved fields in CTP",
         "non-zero reserved fields in PTE",
-        "Unknown"
 };
 #define MAX_FAULT_REASON_IDX    (ARRAY_SIZE(fault_reason_strings) - 1)
 
-char *dmar_get_fault_reason(u8 fault_reason)
+const char *dmar_get_fault_reason(u8 fault_reason)
 {
-        if (fault_reason >= MAX_FAULT_REASON_IDX)
-                return fault_reason_strings[MAX_FAULT_REASON_IDX - 1];
+        if (fault_reason > MAX_FAULT_REASON_IDX)
+                return "Unknown";
         else
                 return fault_reason_strings[fault_reason];
 }
@@ -825,7 +824,7 @@ void dmar_msi_read(int irq, struct msi_msg *msg)
 static int iommu_page_fault_do_one(struct intel_iommu *iommu, int type,
                 u8 fault_reason, u16 source_id, u64 addr)
 {
-        char *reason;
+        const char *reason;
 
         reason = dmar_get_fault_reason(fault_reason);
 
diff --git a/include/linux/dmar.h b/include/linux/dmar.h
index ffb6439cb5e6..56c73b847551 100644
--- a/include/linux/dmar.h
+++ b/include/linux/dmar.h
@@ -28,7 +28,7 @@
 #ifdef CONFIG_DMAR
 struct intel_iommu;
 
-extern char *dmar_get_fault_reason(u8 fault_reason);
+extern const char *dmar_get_fault_reason(u8 fault_reason);
 
 /* Can't use the common MSI interrupt functions
  * since DMAR is not a pci device