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perf/x86/intel: Fix static checker warning in lbr enable 

Commit deb27519bf ("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: deb27519bf ("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>
This commit is contained in:
Kan Liang 2015-09-14 10:14:07 -04:00 committed by Ingo Molnar
parent 02386c356a
commit 96f3eda67f
1 changed files with 3 additions and 2 deletions
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5
arch/x86/kernel/cpu/perf_event_intel_lbr.c
View File

@ -151,8 +151,9 @@ static void __intel_pmu_lbr_enable(bool pmi)
* 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);