#include <linux/sched.h>
#include <linux/sched/idle.h>
#include <linux/hypervisor.h>
+#include <linux/sched/clock.h>
+#include <linux/nmi.h>
+#include <linux/sched/debug.h>
#include "smpboot.h"
#include "sched/smp.h"
smpcfd_prepare_cpu(smp_processor_id());
}
+#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
+
+static DEFINE_PER_CPU(call_single_data_t *, cur_csd);
+static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func);
+static DEFINE_PER_CPU(void *, cur_csd_info);
+
+#define CSD_LOCK_TIMEOUT (5ULL * NSEC_PER_SEC)
+static atomic_t csd_bug_count = ATOMIC_INIT(0);
+
+/* Record current CSD work for current CPU, NULL to erase. */
+static void csd_lock_record(call_single_data_t *csd)
+{
+ if (!csd) {
+ smp_mb(); /* NULL cur_csd after unlock. */
+ __this_cpu_write(cur_csd, NULL);
+ return;
+ }
+ __this_cpu_write(cur_csd_func, csd->func);
+ __this_cpu_write(cur_csd_info, csd->info);
+ smp_wmb(); /* func and info before csd. */
+ __this_cpu_write(cur_csd, csd);
+ smp_mb(); /* Update cur_csd before function call. */
+ /* Or before unlock, as the case may be. */
+}
+
+static __always_inline int csd_lock_wait_getcpu(call_single_data_t *csd)
+{
+ unsigned int csd_type;
+
+ csd_type = CSD_TYPE(csd);
+ if (csd_type == CSD_TYPE_ASYNC || csd_type == CSD_TYPE_SYNC)
+ return csd->dst; /* Other CSD_TYPE_ values might not have ->dst. */
+ return -1;
+}
+
+/*
+ * Complain if too much time spent waiting. Note that only
+ * the CSD_TYPE_SYNC/ASYNC types provide the destination CPU,
+ * so waiting on other types gets much less information.
+ */
+static __always_inline bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id)
+{
+ int cpu = -1;
+ int cpux;
+ bool firsttime;
+ u64 ts2, ts_delta;
+ call_single_data_t *cpu_cur_csd;
+ unsigned int flags = READ_ONCE(csd->flags);
+
+ if (!(flags & CSD_FLAG_LOCK)) {
+ if (!unlikely(*bug_id))
+ return true;
+ cpu = csd_lock_wait_getcpu(csd);
+ pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n",
+ *bug_id, raw_smp_processor_id(), cpu);
+ return true;
+ }
+
+ ts2 = sched_clock();
+ ts_delta = ts2 - *ts1;
+ if (likely(ts_delta <= CSD_LOCK_TIMEOUT))
+ return false;
+
+ firsttime = !*bug_id;
+ if (firsttime)
+ *bug_id = atomic_inc_return(&csd_bug_count);
+ cpu = csd_lock_wait_getcpu(csd);
+ if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu))
+ cpux = 0;
+ else
+ cpux = cpu;
+ cpu_cur_csd = smp_load_acquire(&per_cpu(cur_csd, cpux)); /* Before func and info. */
+ pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %llu ns for CPU#%02d %pS(%ps).\n",
+ firsttime ? "Detected" : "Continued", *bug_id, raw_smp_processor_id(), ts2 - ts0,
+ cpu, csd->func, csd->info);
+ if (cpu_cur_csd && csd != cpu_cur_csd) {
+ pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n",
+ *bug_id, READ_ONCE(per_cpu(cur_csd_func, cpux)),
+ READ_ONCE(per_cpu(cur_csd_info, cpux)));
+ } else {
+ pr_alert("\tcsd: CSD lock (#%d) %s.\n",
+ *bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request");
+ }
+ if (cpu >= 0) {
+ if (!trigger_single_cpu_backtrace(cpu))
+ dump_cpu_task(cpu);
+ if (!cpu_cur_csd) {
+ pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu);
+ arch_send_call_function_single_ipi(cpu);
+ }
+ }
+ dump_stack();
+ *ts1 = ts2;
+
+ return false;
+}
+
/*
* csd_lock/csd_unlock used to serialize access to per-cpu csd resources
*
* previous function call. For multi-cpu calls its even more interesting
* as we'll have to ensure no other cpu is observing our csd.
*/
+static __always_inline void csd_lock_wait(call_single_data_t *csd)
+{
+ int bug_id = 0;
+ u64 ts0, ts1;
+
+ ts1 = ts0 = sched_clock();
+ for (;;) {
+ if (csd_lock_wait_toolong(csd, ts0, &ts1, &bug_id))
+ break;
+ cpu_relax();
+ }
+ smp_acquire__after_ctrl_dep();
+}
+
+#else
+static void csd_lock_record(call_single_data_t *csd)
+{
+}
+
static __always_inline void csd_lock_wait(call_single_data_t *csd)
{
smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK));
}
+#endif
static __always_inline void csd_lock(call_single_data_t *csd)
{
* We can unlock early even for the synchronous on-stack case,
* since we're doing this from the same CPU..
*/
+ csd_lock_record(csd);
csd_unlock(csd);
local_irq_save(flags);
func(info);
+ csd_lock_record(NULL);
local_irq_restore(flags);
return 0;
}
entry = &csd_next->llist;
}
+ csd_lock_record(csd);
func(info);
csd_unlock(csd);
+ csd_lock_record(NULL);
} else {
prev = &csd->llist;
}
smp_call_func_t func = csd->func;
void *info = csd->info;
+ csd_lock_record(csd);
csd_unlock(csd);
func(info);
+ csd_lock_record(NULL);
} else if (type == CSD_TYPE_IRQ_WORK) {
irq_work_single(csd);
}
csd->func = func;
csd->info = info;
+#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
+ csd->src = smp_processor_id();
+ csd->dst = cpu;
+#endif
err = generic_exec_single(cpu, csd);
csd->flags |= CSD_TYPE_SYNC;
csd->func = func;
csd->info = info;
+#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
+ csd->src = smp_processor_id();
+ csd->dst = cpu;
+#endif
if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
}
* for all the required CPUs to finish. This may include the local
* processor.
* @cond_func: A callback function that is passed a cpu id and
- * the the info parameter. The function is called
+ * the info parameter. The function is called
* with preemption disabled. The function should
* return a blooean value indicating whether to IPI
* the specified CPU.
projects / linux-2.6-microblaze.git / blobdiff