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SubjectRE: efi_pstore: question about how to remove create_sysfs_entry() from a write callback.
Date
Mike,

Previous pseudo code was not correct.
More precisely, it is as follows.
But, we still need to alloc memory dynamically in the part of <Save information about new entry>
because a workqueue can't know how many new entries in advance.

spin_lock_irqsave(&efivars_lock);

do {
get_next_variable();
if (found new entry)
<Save information about new entry>

} while()

spin_lock_irqrestore(&efivars_lock);

efivars_create_sysfs_entries();

Seiji

> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Seiji Aguchi
> Sent: Tuesday, August 14, 2012 2:52 PM
> To: Mike Waychison
> Cc: linux-kernel@vger.kernel.org; Luck, Tony (tony.luck@intel.com); Matthew Garrett (mjg@redhat.com); dzickus@redhat.com; dle-
> develop@lists.sourceforge.net; Satoru Moriya
> 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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