From: Arnd Bergmann arnd@arndb.de
This patch has been added to the 4.1 stable tree. If you have any objections, please let us know.
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[ Upstream commit 11d8b05855f3749bcb6c57e2c4052921b9605c77 ]
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 peterz@infradead.org Signed-off-by: Arnd Bergmann arnd@arndb.de Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Andy Lutomirski luto@kernel.org Cc: Arnaldo Carvalho de Melo acme@kernel.org Cc: Josh Poimboeuf jpoimboe@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Thomas Gleixner tglx@linutronix.de Link: http://lkml.kernel.org/r/20170719125310.2487451-2-arnd@arndb.de Link: https://patchwork.kernel.org/patch/9392595/ Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/x86/kernel/cpu/perf_event.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 83f33a2e662f..904b31ebc419 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -187,8 +187,8 @@ 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;