From: Arnd Bergmann Date: Wed, 19 Jul 2017 12:52:59 +0000 (+0200) Subject: perf/x86: Shut up false-positive -Wmaybe-uninitialized warning X-Git-Tag: v4.4.118~51 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e787fce41c0746e39b9edafcadb3c4d05b43d063;p=thirdparty%2Fkernel%2Fstable.git perf/x86: Shut up false-positive -Wmaybe-uninitialized warning commit 11d8b05855f3749bcb6c57e2c4052921b9605c77 upstream. 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 Signed-off-by: Arnd Bergmann Cc: Alexander Shishkin Cc: Andy Lutomirski Cc: Arnaldo Carvalho de Melo Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20170719125310.2487451-2-arnd@arndb.de Link: https://patchwork.kernel.org/patch/9392595/ Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 5b2f2306fbcc4..b52a8d08ab363 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -188,8 +188,8 @@ 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;