perf/x86: Shut up false-positive -Wmaybe-uninitialized warning

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.

Suggested-by: Peter Zijlstra <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Link: https://patchwork.kernel.org/patch/9392595/
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index ff1ea2fb97055e4d6a3282a18c16a0eea689c29a..8e3db8f642a7a02dd8f99db3a25dedbfd1deb01a 100644 (file)
--- 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;