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

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Date:	Tue, 14 Aug 2012 18:51:59 +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.

> Can we not serialize this with &efivars->lock if it is updated to disable interrupts?  A loop in the workqueue that locks, iterates through
> ->get_next_variable, and compares against searches in
> efivars->list should work, no?

If my understanding is correct, your pseudo code is as follows.

spin_lock_irqsave(&efivars_lock);

do {
	get_next_variable();
	if (found new entry)
 		efivars_create_sysfs_entries();

} while()

spin_lock_irqrestore(&efivars_lock);

But, memory is allocated dynamically with kzalloc() in efivars_create_sysfs_entries().
I don't want to allocate memory  while holding spin_lock.

Please let me know if I'm missing something.

Seiji 
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