Hi Alan,
looking at this code:
unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
{
const struct block_device_operations *bdops = disk->fops;
struct disk_events *ev = disk->ev;
unsigned int pending;
if (!ev) {
/* for drivers still using the old ->media_changed method */
if ((mask & DISK_EVENT_MEDIA_CHANGE) &&
bdops->media_changed && bdops->media_changed(disk))
return DISK_EVENT_MEDIA_CHANGE;
return 0;
}
/* tell the workfn about the events being cleared */
spin_lock_irq(&ev->lock);
ev->clearing |= mask;
spin_unlock_irq(&ev->lock);
/* uncondtionally schedule event check and wait for it to finish */
disk_block_events(disk);
queue_delayed_work(system_nrt_freezable_wq, &ev->dwork, 0);
<-- window for race with freezer
flush_delayed_work(&ev->dwork);
__disk_unblock_events(disk, false);
/* then, fetch and clear pending events */
spin_lock_irq(&ev->lock);
WARN_ON_ONCE(ev->clearing & mask); /* cleared by workfn */
pending = ev->pending & mask;
ev->pending &= ~mask;
spin_unlock_irq(&ev->lock);
return pending;
}
What happens if the freezer starts during the window? It seems to me
that the task flushing work would block and could not be frozen.
Regards
Oliver
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