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Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git

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This commit is contained in:
Stephen Rothwell 2024-12-20 14:16:39 +11:00
commit 3feff3acfa
2 changed files with 29 additions and 11 deletions
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22
kernel/workqueue.c
View File

@ -3680,23 +3680,27 @@ void workqueue_softirq_dead(unsigned int cpu)
* check_flush_dependency - check for flush dependency sanity
* @target_wq: workqueue being flushed
* @target_work: work item being flushed (NULL for workqueue flushes)
* @from_cancel: are we called from the work cancel path
*
* %current is trying to flush the whole @target_wq or @target_work on it.
* If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not
* reclaiming memory or running on a workqueue which doesn't have
* %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to
* a deadlock.
* If this is not the cancel path (which implies work being flushed is either
* already running, or will not be at all), check if @target_wq doesn't have
* %WQ_MEM_RECLAIM and verify that %current is not reclaiming memory or running
* on a workqueue which doesn't have %WQ_MEM_RECLAIM as that can break forward-
* progress guarantee leading to a deadlock.
*/
static void check_flush_dependency(struct workqueue_struct *target_wq,
struct work_struct *target_work)
struct work_struct *target_work,
bool from_cancel)
{
work_func_t target_func = target_work ? target_work->func : NULL;
work_func_t target_func;
struct worker *worker;
if (target_wq->flags & WQ_MEM_RECLAIM)
if (from_cancel || target_wq->flags & WQ_MEM_RECLAIM)
return;
worker = current_wq_worker();
target_func = target_work ? target_work->func : NULL;
WARN_ONCE(current->flags & PF_MEMALLOC,
"workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps",
@ -3980,7 +3984,7 @@ void __flush_workqueue(struct workqueue_struct *wq)
list_add_tail(&this_flusher.list, &wq->flusher_overflow);
}
check_flush_dependency(wq, NULL);
check_flush_dependency(wq, NULL, false);
mutex_unlock(&wq->mutex);
@ -4155,7 +4159,7 @@ static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr,
}
wq = pwq->wq;
check_flush_dependency(wq, work);
check_flush_dependency(wq, work, from_cancel);
insert_wq_barrier(pwq, barr, work, worker);
raw_spin_unlock_irq(&pool->lock);

18
rust/kernel/workqueue.rs
View File

@ -519,7 +519,15 @@ unsafe fn raw_get_work(ptr: *mut Self) -> *mut $crate::workqueue::Work<$work_typ
impl{T} HasWork<Self> for ClosureWork<T> { self.work }
}
// SAFETY: TODO.
// SAFETY: The `__enqueue` implementation in RawWorkItem uses a `work_struct` initialized with the
// `run` method of this trait as the function pointer because:
// - `__enqueue` gets the `work_struct` from the `Work` field, using `T::raw_get_work`.
// - The only safe way to create a `Work` object is through `Work::new`.
// - `Work::new` makes sure that `T::Pointer::run` is passed to `init_work_with_key`.
// - Finally `Work` and `RawWorkItem` guarantee that the correct `Work` field
// will be used because of the ID const generic bound. This makes sure that `T::raw_get_work`
// uses the correct offset for the `Work` field, and `Work::new` picks the correct
// implementation of `WorkItemPointer` for `Arc<T>`.
unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Arc<T>
where
T: WorkItem<ID, Pointer = Self>,
@ -537,7 +545,13 @@ unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Arc<T>
}
}
// SAFETY: TODO.
// SAFETY: The `work_struct` raw pointer is guaranteed to be valid for the duration of the call to
// the closure because we get it from an `Arc`, which means that the ref count will be at least 1,
// and we don't drop the `Arc` ourselves. If `queue_work_on` returns true, it is further guaranteed
// to be valid until a call to the function pointer in `work_struct` because we leak the memory it
// points to, and only reclaim it if the closure returns false, or in `WorkItemPointer::run`, which
// is what the function pointer in the `work_struct` must be pointing to, according to the safety
// requirements of `WorkItemPointer`.
unsafe impl<T, const ID: u64> RawWorkItem<ID> for Arc<T>
where
T: WorkItem<ID, Pointer = Self>,