linux-kernel - RE: efi_pstore: question about how to remove create_sysfs

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Date:	Tue, 14 Aug 2012 21:38:20 +0000
From:	Seiji Aguchi <seiji.aguchi@....com>
To:	Mike Waychison <mikew@...gle.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Luck, Tony (tony.luck@...el.com)" <tony.luck@...el.com>,
	"Matthew Garrett (mjg@...hat.com)" <mjg@...hat.com>,
	"dzickus@...hat.com" <dzickus@...hat.com>,
	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>,
	Satoru Moriya <satoru.moriya@....com>
Subject: RE: efi_pstore: question about how to remove create_sysfs_entry()
 from a write callback.

> 
> Something like this (pseudo) may work:
> 
> /* Loop until we have all entries in efivars. */ while (1) {
>   variable_name = kzalloc(1024, GFP_KERNEL );
>   spin_lock_irqsave(&efivars->lock);
>   bool found = false;
>   while (1) {
>      ret = ops->get_next_variable(variable_name)
>      if (ret == EFI_NOT_FOUND)
>         break;
>      if (!variable_is_already_present(variable, &efivars->list) {
>        found = true;
>        break;
>      }
>   }
>   if (!found) {
>     kfree(variable_name);
>     break;
>   }
>   <Register in sysfs>
> }
> 

Thanks. It seems to work.
I will create a patch based on your pseudo code above.

> 
> If we are calling into pstore_info ops though from interrupt context, it seems we'll need to fix the immediate problem of updating the
> locking throughout to be interrupt safe.
> 

I agree with you. It should be fixing.  I will update the locking to be interrupt safe as well.

Seiji
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