x86/oprofile: Fix uninitialized variable use in debug printk

Stephen Rothwell reported this build warning:

  arch/x86/oprofile/op_model_amd.c: In function 'ibs_eilvt_valid':
  arch/x86/oprofile/op_model_amd.c:289: warning: 'offset' may be used uninitialized in this function

And correctly observed that indeed the variable is used uninitialized in
this function. The result of this bug can be a debug printk with a bogus
value.

Also fix a few more small details that made this function hard to read
and which probably contributed to the bug being introduced to begin with:

 - Use more symmetric error conditions

 - Remove the !0 obfuscation

 - Add newlines to the printk output

 - Remove bogus linebreaks in printk strings and elsewhere

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20101025115736.41d51abe.sfr@canb.auug.org.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/oprofile/op_model_amd.c b/arch/x86/oprofile/op_model_amd.c
index 42fb46f..68759e7 100644 (file)
--- a/arch/x86/oprofile/op_model_amd.c
+++ b/arch/x86/oprofile/op_model_amd.c
@@ -281,29 +281,25 @@ static inline int eilvt_is_available(int offset)
 
 static inline int ibs_eilvt_valid(void)
 {
-       u64 val;
        int offset;
+       u64 val;
 
        rdmsrl(MSR_AMD64_IBSCTL, val);
+       offset = val & IBSCTL_LVT_OFFSET_MASK;
+
        if (!(val & IBSCTL_LVT_OFFSET_VALID)) {
-               pr_err(FW_BUG "cpu %d, invalid IBS "
-                      "interrupt offset %d (MSR%08X=0x%016llx)",
-                      smp_processor_id(), offset,
-                      MSR_AMD64_IBSCTL, val);
+               pr_err(FW_BUG "cpu %d, invalid IBS interrupt offset %d (MSR%08X=0x%016llx)\n",
+                      smp_processor_id(), offset, MSR_AMD64_IBSCTL, val);
                return 0;
        }
 
-       offset = val & IBSCTL_LVT_OFFSET_MASK;
-
-       if (eilvt_is_available(offset))
-               return !0;
-
-       pr_err(FW_BUG "cpu %d, IBS interrupt offset %d "
-              "not available (MSR%08X=0x%016llx)",
-              smp_processor_id(), offset,
-              MSR_AMD64_IBSCTL, val);
+       if (!eilvt_is_available(offset)) {
+               pr_err(FW_BUG "cpu %d, IBS interrupt offset %d not available (MSR%08X=0x%016llx)\n",
+                      smp_processor_id(), offset, MSR_AMD64_IBSCTL, val);
+               return 0;
+       }
 
-       return 0;
+       return 1;
 }
 
 static inline int get_ibs_offset(void)