linux-kernel - Re: [PATCH v3] efivars,efi-pstore: Hold off deletion of sysfs entry until, the scan is completed

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Message-ID: <20131030143527.GB8193@console-pimps.org>
Date:	Wed, 30 Oct 2013 14:35:27 +0000
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Seiji Aguchi <seiji.aguchi@....com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"matt.fleming@...el.com" <matt.fleming@...el.com>,
	"tony.luck@...el.com" <tony.luck@...el.com>,
	Tomoki Sekiyama <tomoki.sekiyama@....com>,
	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>
Subject: Re: [PATCH v3] efivars,efi-pstore: Hold off deletion of sysfs entry
 until, the scan is completed

On Fri, 18 Oct, at 10:30:58PM, Seiji Aguchi wrote:
> The scanning and deleting logic is still needed.  In case an entry(A)
> is found, the pointer is saved to psi->data.  And efi_pstore_read()
> passes the entry(A) to a pstore filesystem by releasing
> __efivars->lock.
> 
> And then, the pstore filesystem calls efi_pstore_read() again and the
> same entry(A), which is saved to psi->data, is used for re-scanning a
> sysfs-list.  (That is why list_for_each_entry_safe_from () is used in
> efi_pstore_sysfs_entry_iter().)
> 
> So, to protect the entry(A), the logic is needed because, in pstore
> filesystem,  __efivars->lock Is released. 
 
Very good point.

-- 
Matt Fleming, Intel Open Source Technology Center
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