linux-kernel - Re: [PATCH 1/4] ACPI: Add acpi_pr

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Message-ID: <1342649174.2215.19.camel@joe2Laptop>
Date:	Wed, 18 Jul 2012 15:06:14 -0700
From:	Joe Perches <joe@...ches.com>
To:	Toshi Kani <toshi.kani@...com>
Cc:	lenb@...nel.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, bhelgaas@...gle.com,
	isimatu.yasuaki@...fujitsu.com, liuj97@...il.com,
	srivatsa.bhat@...ux.vnet.ibm.com, prarit@...hat.com,
	imammedo@...hat.com, vijaymohan.pandarathil@...com
Subject: Re: [PATCH 1/4] ACPI: Add acpi_pr_<level>() interfaces

On Wed, 2012-07-18 at 15:41 -0600, Toshi Kani wrote:
> On Wed, 2012-07-18 at 14:27 -0700, Joe Perches wrote:
> > On Wed, 2012-07-18 at 14:40 -0600, Toshi Kani wrote:
> > > This patch introduces acpi_pr_<level>(), where <level> is a message
> > > level such as err/warn/info, to support improved logging messages
> > > for ACPI, esp. in hotplug operations.
> > 
> > One more note:
> > 
> > > diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
> > []
> > > @@ -454,3 +454,35 @@ acpi_evaluate_hotplug_ost(acpi_handle handle, u32 source_event,
> > []
> > > +void
> > > +acpi_printk(const char *level, acpi_handle handle, const char *fmt, ...)
> > []
> > > +	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER};
> > []
> > > +	ret = acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
> > []
> > > +	kfree(buffer.pointer);
> > 
> > There's a failure mode here because buffer.pointer
> > isn't guaranteed to be initialized or set to NULL.
> 
> Hi Joe,
> 
> Yes, I thought that check was necessary as well.  However, to my
> surprise, such check caused the following warning message from
> patchcheck.pl.  So, I deleted the check...

checkpatch ain't very bright.

Because buffer is an automatic not a static,
buffer.pointer needs to be set to NULL.

	struct acpi_buffer buffer = {
		.length = ACPI_ALLOCATE_BUFFER,
		.pointer = NULL,
	};

then the kfree is fine.

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