From: Ingo Molnar Date: Mon, 25 Oct 2010 06:41:09 +0000 (+0200) Subject: x86/oprofile: Fix uninitialized variable use in debug printk X-Git-Tag: v2.6.37-rc1~18^2~5 X-Git-Url: https://bbs.cooldavid.org/git/?a=commitdiff_plain;h=2c78ffeca98fcd5a1dfd4a322438944506ed5e64;p=net-next-2.6.git 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 Cc: Robert Richter Cc: Linus Torvalds LKML-Reference: <20101025115736.41d51abe.sfr@canb.auug.org.au> Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/oprofile/op_model_amd.c b/arch/x86/oprofile/op_model_amd.c index 42fb46f8388..68759e716f0 100644 --- 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)