On 7/18/22 08:34, Christoph Hellwig wrote:
Just do a simple list_for_each_entry_safe on all_mddevs, and only grab a reference when we drop the lock. Reviewed-by: Christoph Hellwig <hch@xxxxxx> --- drivers/md/md.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 687f320c7ec4a..44e4071b43148 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -9587,11 +9587,13 @@ EXPORT_SYMBOL_GPL(rdev_clear_badblocks); static int md_notify_reboot(struct notifier_block *this, unsigned long code, void *x) { - struct list_head *tmp; - struct mddev *mddev; + struct mddev *mddev, *n; int need_delay = 0;- for_each_mddev(mddev, tmp) {+ spin_lock(&all_mddevs_lock); + list_for_each_entry_safe(mddev, n, &all_mddevs, all_mddevs) { + mddev_get(mddev); + spin_unlock(&all_mddevs_lock); if (mddev_trylock(mddev)) { if (mddev->pers) __md_stop_writes(mddev); @@ -9600,7 +9602,11 @@ static int md_notify_reboot(struct notifier_block *this, mddev_unlock(mddev); } need_delay = 1; + mddev_put(mddev); + spin_lock(&all_mddevs_lock); } + spin_unlock(&all_mddevs_lock); + /* * certain more exotic SCSI devices are known to be * volatile wrt too early system reboots. While the
I wish 'mddev_get()' could fail if 'mddev->active' is zero when we call it ... but maybe for another time.
Reviewed-by: Hannes Reinecke <hare@xxxxxxx> Cheers, Hannes
