The patch titled
make queue_delayed_work() friendly to flush_fork()
has been added to the -mm tree. Its filename is
make-queue_delayed_work-friendly-to-flush_fork.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: make queue_delayed_work() friendly to flush_fork()
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Currently typeof(delayed_work->work.data) is
"struct workqueue_struct" when the timer is pending
"struct cpu_workqueue_struct" whe the work is queued
This makes impossible to use flush_fork(delayed_work->work) in addition
to cancel_delayed_work/cancel_rearming_delayed_work, not good.
Change queue_delayed_work/delayed_work_timer_fn to use cwq, not wq. This
complicates (and uglifies) these functions a little bit, but alows us to
use flush_fork(dwork) and imho makes the whole code more consistent.
Also, document the fact that cancel_rearming_delayed_work() doesn't garantee
the completion of work->func() upon return.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/workqueue.h | 2 +-
kernel/workqueue.c | 28 ++++++++++++++++++----------
2 files changed, 19 insertions(+), 11 deletions(-)
diff -puN include/linux/workqueue.h~make-queue_delayed_work-friendly-to-flush_fork include/linux/workqueue.h
--- a/include/linux/workqueue.h~make-queue_delayed_work-friendly-to-flush_fork
+++ a/include/linux/workqueue.h
@@ -193,7 +193,7 @@ int execute_in_process_context(work_func
/*
* Kill off a pending schedule_delayed_work(). Note that the work callback
* function may still be running on return from cancel_delayed_work(). Run
- * flush_scheduled_work() or flush_work() to wait on it.
+ * flush_workqueue() or flush_work() to wait on it.
*/
static inline int cancel_delayed_work(struct delayed_work *work)
{
diff -puN kernel/workqueue.c~make-queue_delayed_work-friendly-to-flush_fork kernel/workqueue.c
--- a/kernel/workqueue.c~make-queue_delayed_work-friendly-to-flush_fork
+++ a/kernel/workqueue.c
@@ -90,18 +90,20 @@ static const cpumask_t *wq_cpu_map(struc
* Set the workqueue on which a work item is to be run
* - Must *only* be called if the pending flag is set
*/
-static inline void set_wq_data(struct work_struct *work, void *wq)
+static inline void set_wq_data(struct work_struct *work,
+ struct cpu_workqueue_struct *cwq)
{
unsigned long new;
BUG_ON(!work_pending(work));
- new = (unsigned long) wq | (1UL << WORK_STRUCT_PENDING);
+ new = (unsigned long) cwq | (1UL << WORK_STRUCT_PENDING);
new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work);
atomic_long_set(&work->data, new);
}
-static inline void *get_wq_data(struct work_struct *work)
+static inline
+struct cpu_workqueue_struct *get_wq_data(struct work_struct *work)
{
return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK);
}
@@ -157,7 +159,8 @@ EXPORT_SYMBOL_GPL(queue_work);
void delayed_work_timer_fn(unsigned long __data)
{
struct delayed_work *dwork = (struct delayed_work *)__data;
- struct workqueue_struct *wq = get_wq_data(&dwork->work);
+ struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work);
+ struct workqueue_struct *wq = cwq->wq;
int cpu = smp_processor_id();
if (unlikely(is_single_threaded(wq)))
@@ -189,8 +192,9 @@ int fastcall queue_delayed_work(struct w
BUG_ON(timer_pending(timer));
BUG_ON(!list_empty(&work->entry));
- /* This stores wq for the moment, for the timer_fn */
- set_wq_data(work, wq);
+ /* This stores cwq for the moment, for the timer_fn */
+ set_wq_data(work,
+ per_cpu_ptr(wq->cpu_wq, raw_smp_processor_id()));
timer->expires = jiffies + delay;
timer->data = (unsigned long)dwork;
timer->function = delayed_work_timer_fn;
@@ -221,8 +225,9 @@ int queue_delayed_work_on(int cpu, struc
BUG_ON(timer_pending(timer));
BUG_ON(!list_empty(&work->entry));
- /* This stores wq for the moment, for the timer_fn */
- set_wq_data(work, wq);
+ /* This stores cwq for the moment, for the timer_fn */
+ set_wq_data(work,
+ per_cpu_ptr(wq->cpu_wq, raw_smp_processor_id()));
timer->expires = jiffies + delay;
timer->data = (unsigned long)dwork;
timer->function = delayed_work_timer_fn;
@@ -562,9 +567,12 @@ void flush_work_keventd(struct work_stru
EXPORT_SYMBOL(flush_work_keventd);
/**
- * cancel_rearming_delayed_workqueue - reliably kill off a delayed work whose handler rearms the delayed work.
+ * cancel_rearming_delayed_workqueue - kill off a delayed work whose handler rearms the delayed work.
* @wq: the controlling workqueue structure
* @dwork: the delayed work struct
+ *
+ * Note that the work callback function may still be running on return from
+ * cancel_delayed_work(). Run flush_workqueue() or flush_work() to wait on it.
*/
void cancel_rearming_delayed_workqueue(struct workqueue_struct *wq,
struct delayed_work *dwork)
@@ -579,7 +587,7 @@ void cancel_rearming_delayed_workqueue(s
EXPORT_SYMBOL(cancel_rearming_delayed_workqueue);
/**
- * cancel_rearming_delayed_work - reliably kill off a delayed keventd work whose handler rearms the delayed work.
+ * cancel_rearming_delayed_work - kill off a delayed keventd work whose handler rearms the delayed work.
* @dwork: the delayed work struct
*/
void cancel_rearming_delayed_work(struct delayed_work *dwork)
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
git-block.patch
smaps-add-clear_refs-file-to-clear-reference-fix.patch
doc-atomic_add_unless-doesnt-imply-mb-on-failure.patch
procfs-fix-race-between-proc_readdir-and-remove_proc_entry.patch
procfs-fix-race-between-proc_readdir-and-remove_proc_entry-fix.patch
clone-flag-clone_parent_tidptr-leaves-invalid-results-in-memory.patch
allow-access-to-proc-pid-fd-after-setuid.patch
allow-access-to-proc-pid-fd-after-setuid-fix.patch
allow-access-to-proc-pid-fd-after-setuid-update.patch
posix-timers-rcu-optimization-for-clock_gettime.patch
posix-timers-rcu-optimization-for-clock_gettime-fix.patch
reimplement-flush_workqueue.patch
implement-flush_work.patch
implement-flush_work-sanity.patch
implement-flush_work_keventd.patch
flush_workqueue-use-preempt_disable-to-hold-off-cpu-hotplug.patch
flush_cpu_workqueue-dont-flush-an-empty-worklist.patch
aio-use-flush_work.patch
kblockd-use-flush_work.patch
relayfs-use-flush_keventd_work.patch
tg3-use-flush_keventd_work.patch
e1000-use-flush_keventd_work.patch
libata-use-flush_work.patch
phy-use-flush_work.patch
call-cpu_chain-with-cpu_down_failed-if-cpu_down_prepare-failed.patch
slab-use-cpu_lock_.patch
workqueue-fix-freezeable-workqueues-implementation.patch
workqueue-fix-flush_workqueue-vs-cpu_dead-race.patch
workqueue-dont-clear-cwq-thread-until-it-exits.patch
workqueue-dont-migrate-pending-works-from-the-dead-cpu.patch
workqueue-kill-run_scheduled_work.patch
workqueue-dont-save-interrupts-in-run_workqueue.patch
workqueue-dont-save-interrupts-in-run_workqueue-update-2.patch
workqueue-make-cancel_rearming_delayed_workqueue-work-on-idle-dwork.patch
workqueue-introduce-cpu_singlethread_map.patch
workqueue-introduce-workqueue_struct-singlethread.patch
workqueue-make-init_workqueues-__init.patch
make-queue_delayed_work-friendly-to-flush_fork.patch
slab-shutdown-cache_reaper-when-cpu-goes-down.patch
rework-compat_sys_io_submit.patch
fix-aioh-includes.patch
fix-access_ok-checks.patch
make-good_sigevent-non-static.patch
make-good_sigevent-non-static-fix.patch
make-__sigqueue_free-and.patch
aio-completion-signal-notification.patch
aio-completion-signal-notification-fix.patch
aio-completion-signal-notification-fixes-and-cleanups.patch
aio-completion-signal-notification-small-cleanup.patch
add-listio-syscall-support.patch
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