From: Arnd Bergmann <arnd@xxxxxxxx>
This patch has been added to the 4.1 stable tree. If you have any
objections, please let us know.
===============
[ 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@xxxxxxxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20170719125310.2487451-2-arnd@xxxxxxxx
Link: https://patchwork.kernel.org/patch/9392595/
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
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;
--
2.14.1