perf/x86/intel: Fix static checker warning in lbr enable
Commit deb27519bf1f ("perf/x86/intel: Fix LBR callstack issue caused
by FREEZE_LBRS_ON_PMI") leads to the following Smatch complaint:
warn: variable dereferenced before check 'cpuc->lbr_sel' (see line 154)
Fix the warning.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: deb27519bf1f ("perf/x86/intel: Fix LBR callstack issue caused by FREEZE_LBRS_ON_PMI")
Link: http://lkml.kernel.org/r/1442240047-48149-1-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index a1d07c7..ad0b8b0 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -151,8 +151,9 @@
* No need to reprogram LBR_SELECT in a PMI, as it
* did not change.
*/
- lbr_select = cpuc->lbr_sel->config;
- if (cpuc->lbr_sel && !pmi)
+ if (cpuc->lbr_sel)
+ lbr_select = cpuc->lbr_sel->config;
+ if (!pmi)
wrmsrl(MSR_LBR_SELECT, lbr_select);
rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
