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authorLinus Torvalds <torvalds@linux-foundation.org>2021-04-28 23:33:57 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-04-28 23:33:57 +0300
commit16b3d0cf5bad844daaf436ad2e9061de0fe36e5c (patch)
treed553a51e6d95fb166df7fa62264e9a27e4c438a4 /kernel/kthread.c
parent42dec9a936e7696bea1f27d3c5a0068cd9aa95fd (diff)
parent2ea46c6fc9452ac100ad907b051d797225847e33 (diff)
downloadlinux-16b3d0cf5bad844daaf436ad2e9061de0fe36e5c.tar.xz
Merge tag 'sched-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar: - Clean up SCHED_DEBUG: move the decades old mess of sysctl, procfs and debugfs interfaces to a unified debugfs interface. - Signals: Allow caching one sigqueue object per task, to improve performance & latencies. - Improve newidle_balance() irq-off latencies on systems with a large number of CPU cgroups. - Improve energy-aware scheduling - Improve the PELT metrics for certain workloads - Reintroduce select_idle_smt() to improve load-balancing locality - but without the previous regressions - Add 'scheduler latency debugging': warn after long periods of pending need_resched. This is an opt-in feature that requires the enabling of the LATENCY_WARN scheduler feature, or the use of the resched_latency_warn_ms=xx boot parameter. - CPU hotplug fixes for HP-rollback, and for the 'fail' interface. Fix remaining balance_push() vs. hotplug holes/races - PSI fixes, plus allow /proc/pressure/ files to be written by CAP_SYS_RESOURCE tasks as well - Fix/improve various load-balancing corner cases vs. capacity margins - Fix sched topology on systems with NUMA diameter of 3 or above - Fix PF_KTHREAD vs to_kthread() race - Minor rseq optimizations - Misc cleanups, optimizations, fixes and smaller updates * tag 'sched-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (61 commits) cpumask/hotplug: Fix cpu_dying() state tracking kthread: Fix PF_KTHREAD vs to_kthread() race sched/debug: Fix cgroup_path[] serialization sched,psi: Handle potential task count underflow bugs more gracefully sched: Warn on long periods of pending need_resched sched/fair: Move update_nohz_stats() to the CONFIG_NO_HZ_COMMON block to simplify the code & fix an unused function warning sched/debug: Rename the sched_debug parameter to sched_verbose sched,fair: Alternative sched_slice() sched: Move /proc/sched_debug to debugfs sched,debug: Convert sysctl sched_domains to debugfs debugfs: Implement debugfs_create_str() sched,preempt: Move preempt_dynamic to debug.c sched: Move SCHED_DEBUG sysctl to debugfs sched: Don't make LATENCYTOP select SCHED_DEBUG sched: Remove sched_schedstats sysctl out from under SCHED_DEBUG sched/numa: Allow runtime enabling/disabling of NUMA balance without SCHED_DEBUG sched: Use cpu_dying() to fix balance_push vs hotplug-rollback cpumask: Introduce DYING mask cpumask: Make cpu_{online,possible,present,active}() inline rseq: Optimise rseq_get_rseq_cs() and clear_rseq_cs() ...
Diffstat (limited to 'kernel/kthread.c')
-rw-r--r--kernel/kthread.c33
1 files changed, 27 insertions, 6 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c
index a1972eba2917..fe3f2a40d61e 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -84,6 +84,25 @@ static inline struct kthread *to_kthread(struct task_struct *k)
return (__force void *)k->set_child_tid;
}
+/*
+ * Variant of to_kthread() that doesn't assume @p is a kthread.
+ *
+ * Per construction; when:
+ *
+ * (p->flags & PF_KTHREAD) && p->set_child_tid
+ *
+ * the task is both a kthread and struct kthread is persistent. However
+ * PF_KTHREAD on it's own is not, kernel_thread() can exec() (See umh.c and
+ * begin_new_exec()).
+ */
+static inline struct kthread *__to_kthread(struct task_struct *p)
+{
+ void *kthread = (__force void *)p->set_child_tid;
+ if (kthread && !(p->flags & PF_KTHREAD))
+ kthread = NULL;
+ return kthread;
+}
+
void free_kthread_struct(struct task_struct *k)
{
struct kthread *kthread;
@@ -168,8 +187,9 @@ EXPORT_SYMBOL_GPL(kthread_freezable_should_stop);
*/
void *kthread_func(struct task_struct *task)
{
- if (task->flags & PF_KTHREAD)
- return to_kthread(task)->threadfn;
+ struct kthread *kthread = __to_kthread(task);
+ if (kthread)
+ return kthread->threadfn;
return NULL;
}
EXPORT_SYMBOL_GPL(kthread_func);
@@ -199,10 +219,11 @@ EXPORT_SYMBOL_GPL(kthread_data);
*/
void *kthread_probe_data(struct task_struct *task)
{
- struct kthread *kthread = to_kthread(task);
+ struct kthread *kthread = __to_kthread(task);
void *data = NULL;
- copy_from_kernel_nofault(&data, &kthread->data, sizeof(data));
+ if (kthread)
+ copy_from_kernel_nofault(&data, &kthread->data, sizeof(data));
return data;
}
@@ -514,9 +535,9 @@ void kthread_set_per_cpu(struct task_struct *k, int cpu)
set_bit(KTHREAD_IS_PER_CPU, &kthread->flags);
}
-bool kthread_is_per_cpu(struct task_struct *k)
+bool kthread_is_per_cpu(struct task_struct *p)
{
- struct kthread *kthread = to_kthread(k);
+ struct kthread *kthread = __to_kthread(p);
if (!kthread)
return false;