linux-kernel - [tip:perf/core] perf/x86/intel: Fix static checker warning in lbr enable

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Message-ID: <tip-96f3eda67fcf2598e9d2794398e0e7ab35138ea6@git.kernel.org>
Date:	Fri, 18 Sep 2015 01:49:33 -0700
From:	tip-bot for Kan Liang <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	kan.liang@...el.com, hpa@...or.com, peterz@...radead.org,
	tglx@...utronix.de, dan.carpenter@...cle.com, mingo@...nel.org,
	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org
Subject: [tip:perf/core] perf/x86/intel:
  Fix static checker warning in lbr enable

Commit-ID:  96f3eda67fcf2598e9d2794398e0e7ab35138ea6
Gitweb:     http://git.kernel.org/tip/96f3eda67fcf2598e9d2794398e0e7ab35138ea6
Author:     Kan Liang <kan.liang@...el.com>
AuthorDate: Mon, 14 Sep 2015 10:14:07 -0400
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 18 Sep 2015 09:24:57 +0200

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@...cle.com>
Signed-off-by: Kan Liang <kan.liang@...el.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.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@...nel.org>
---
 arch/x86/kernel/cpu/perf_event_intel_lbr.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

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 @@ 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);
--
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