> On 22 Mar 2019, at 13.01, Marcin Dziegielewski > <[email protected]> wrote: > > > > On 3/21/19 10:32 AM, Javier González wrote: >>> On 20 Mar 2019, at 16.38, Marcin Dziegielewski >>> <[email protected]> wrote: >>> >>> Currently if we issue reboot to the system pblk will close >>> ungracefully and in consequence it will need recovery on load. >>> >>> This patch propose utilize of reboot notifier feature to trigger >>> gracefull pblk shutdown on reboot. >>> >>> Signed-off-by: Marcin Dziegielewski <[email protected]> >>> --- >>> drivers/lightnvm/core.c | 64 >>> +++++++++++++++++++++++++++++++++++++++---------- >>> 1 file changed, 51 insertions(+), 13 deletions(-) >>> >>> diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c >>> index 5f82036..5488051 100644 >>> --- a/drivers/lightnvm/core.c >>> +++ b/drivers/lightnvm/core.c >>> @@ -27,6 +27,7 @@ >>> #include <linux/miscdevice.h> >>> #include <linux/lightnvm.h> >>> #include <linux/sched/sysctl.h> >>> +#include <linux/reboot.h> >>> >>> static LIST_HEAD(nvm_tgt_types); >>> static DECLARE_RWSEM(nvm_tgtt_lock); >>> @@ -1138,6 +1139,48 @@ struct nvm_dev *nvm_alloc_dev(int node) >>> } >>> EXPORT_SYMBOL(nvm_alloc_dev); >>> >>> +static void _nvm_unregister(struct nvm_dev *dev, bool graceful) >>> +{ >>> + struct nvm_target *t, *tmp; >>> + >>> + mutex_lock(&dev->mlock); >>> + list_for_each_entry_safe(t, tmp, &dev->targets, list) { >>> + if (t->dev->parent != dev) >>> + continue; >>> + __nvm_remove_target(t, graceful); >>> + } >>> + mutex_unlock(&dev->mlock); >>> + >>> + list_del(&dev->devices); >>> + >>> + nvm_free(dev); >>> +} >>> + >>> +static int nvm_notify_reboot(struct notifier_block *this, >>> + unsigned long code, void *x) >>> +{ >>> + struct nvm_dev *dev, *t; >>> + >>> + down_write(&nvm_lock); >>> + if (list_empty(&nvm_devices)) { >>> + up_write(&nvm_lock); >>> + return NOTIFY_DONE; >>> + } >>> + >>> + list_for_each_entry_safe(dev, t, &nvm_devices, devices) >>> + _nvm_unregister(dev, true); >>> + >>> + up_write(&nvm_lock); >>> + >>> + return NOTIFY_DONE; >>> +} >>> + >>> +static struct notifier_block nvm_notifier = { >>> + .notifier_call = nvm_notify_reboot, >>> + .next = NULL, >>> + .priority = INT_MAX, /* before any real devices */ >> Why this priority? > > I believe that is the safest priority for our case, I based on bcache > approach. Should I use other priority? >
I’m not very familiar with the notifier_block. I quick look showed that
most modules do not use it, that’s what I asked. Not real feedback here.
>>> +};
>>> +
>>> int nvm_register(struct nvm_dev *dev)
>>> {
>>> int ret, exp_pool_size;
>>> @@ -1161,8 +1204,11 @@ int nvm_register(struct nvm_dev *dev)
>>> return -ENOMEM;
>>> }
>>>
>>> - /* register device with a supported media manager */
>>> down_write(&nvm_lock);
>>> + if (list_empty(&nvm_devices))
>>> + register_reboot_notifier(&nvm_notifier);
>>> +
>>> + /* register device with a supported media manager */
>>> list_add(&dev->devices, &nvm_devices);
>>> up_write(&nvm_lock);
>>>
>>> @@ -1172,21 +1218,13 @@ int nvm_register(struct nvm_dev *dev)
>>>
>>> void nvm_unregister(struct nvm_dev *dev)
>>> {
>>> - struct nvm_target *t, *tmp;
>>> + down_write(&nvm_lock);
>>>
>>> - mutex_lock(&dev->mlock);
>>> - list_for_each_entry_safe(t, tmp, &dev->targets, list) {
>>> - if (t->dev->parent != dev)
>>> - continue;
>>> - __nvm_remove_target(t, false);
>>> - }
>>> - mutex_unlock(&dev->mlock);
>>> + _nvm_unregister(dev, false);
>> You are adding an extra lock dependency here. I cannot see any obvious
>> problem with it, but you probably want to test this with lock debugging
>> enabled.
>
> It was good suggestion, thanks. With enabled lock debugging I have found
> one potential deadlock, I will send second version of this patch.
>
Cool.
>>> - down_write(&nvm_lock);
>>> - list_del(&dev->devices);
>>> + if (list_empty(&nvm_devices))
>>> + unregister_reboot_notifier(&nvm_notifier);
>>> up_write(&nvm_lock);
>>> -
>>> - nvm_free(dev);
>>> }
>>> EXPORT_SYMBOL(nvm_unregister);
>>>
>>> --
>>> 1.8.3.1
>> Otherwise, I think adding this functionality is beneficial.
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