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[1/8] perf/x86: shut up false-positive -Wmaybe-uninitialized warning

Message ID 20170719125310.2487451-2-arnd@arndb.de
State New
Headers show
Series x86: randconfig warning fixes | expand

Commit Message

Arnd Bergmann July 19, 2017, 12:52 p.m. UTC 
The intialization function checks for various failure scenarios, but
unfortunately the compiler gets a little confused about the possible
combinations, leading to a false-positive build warning when
-Wmaybe-uninitialized is set:

arch/x86/events/core.c: In function ‘init_hw_perf_events’:
arch/x86/events/core.c:264:3: warning: ‘reg_fail’ may be used uninitialized in this function [-Wmaybe-uninitialized]
arch/x86/events/core.c:264:3: warning: ‘val_fail’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   pr_err(FW_BUG "the BIOS has corrupted hw-PMU resources (MSR %x is %Lx)\n",

We can't actually run into this case, so this shuts up the warning
by initializing the variables to a known-invalid state.

Link: https://patchwork.kernel.org/patch/9392595/
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
v2: replaced original patch that reordered the code instead of
adding a fake initialization.
---
 arch/x86/events/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

-- 
2.9.0
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Patch

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index ff1ea2fb9705..8e3db8f642a7 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -191,8 +191,8 @@  static void release_pmc_hardware(void) {}
 
 static bool check_hw_exists(void)
 {
-	u64 val, val_fail, val_new= ~0;
-	int i, reg, reg_fail, ret = 0;
+	u64 val, val_fail = -1, val_new= ~0;
+	int i, reg, reg_fail = -1, ret = 0;
 	int bios_fail = 0;
 	int reg_safe = -1;