[PATCHv3 2/4] kernel/watchdog_hld: Ensure CPU-bound context when creating hardlockup detector event
Pingfan Liu
kernelfans at gmail.com
Wed Oct 13 19:41:53 PDT 2021
hardlockup_detector_event_create() should create perf_event on the
current CPU. Preemption could not get disabled because
perf_event_create_kernel_counter() allocates memory. Instead,
the CPU locality is achieved by processing the code in a per-CPU
bound kthread.
Add a check to prevent mistakes when calling the code in another
code path.
Signed-off-by: Pingfan Liu <kernelfans at gmail.com>
Cc: Petr Mladek <pmladek at suse.com>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Wang Qing <wangqing at vivo.com>
Cc: "Peter Zijlstra (Intel)" <peterz at infradead.org>
Cc: Santosh Sivaraj <santosh at fossix.org>
Cc: linux-arm-kernel at lists.infradead.org
To: linux-kernel at vger.kernel.org
---
kernel/watchdog_hld.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c
index 247bf0b1582c..df010df76576 100644
--- a/kernel/watchdog_hld.c
+++ b/kernel/watchdog_hld.c
@@ -165,10 +165,13 @@ static void watchdog_overflow_callback(struct perf_event *event,
static int hardlockup_detector_event_create(void)
{
- unsigned int cpu = smp_processor_id();
+ unsigned int cpu;
struct perf_event_attr *wd_attr;
struct perf_event *evt;
+ /* This function plans to execute in cpu bound kthread */
+ WARN_ON(!is_percpu_thread());
+ cpu = raw_smp_processor_id();
wd_attr = &wd_hw_attr;
wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
--
2.31.1
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