linux-kernel - Re: [PATCH] omapfb/dss: Delete an error message for a failed memory allocation in three functions

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Message-ID: <15209a13-c53b-068b-c0b2-f073117d39e2@ti.com>
Date:   Mon, 27 Nov 2017 15:33:13 -0600
From:   "Andrew F. Davis" <afd@...com>
To:     Joe Perches <joe@...ches.com>,
        SF Markus Elfring <elfring@...rs.sourceforge.net>,
        <linux-omap@...r.kernel.org>, <linux-fbdev@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>,
        Arvind Yadav <arvind.yadav.cs@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Tomi Valkeinen <tomi.valkeinen@...com>
CC:     LKML <linux-kernel@...r.kernel.org>,
        <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH] omapfb/dss: Delete an error message for a failed memory
 allocation in three functions

On 11/27/2017 01:07 PM, Joe Perches wrote:
> On Mon, 2017-11-27 at 10:43 -0600, Andrew F. Davis wrote:
>> On 11/26/2017 12:55 PM, SF Markus Elfring wrote:
>>> From: Markus Elfring <elfring@...rs.sourceforge.net>
>>> Date: Sun, 26 Nov 2017 19:46:09 +0100
>>>
>>> Omit an extra message for a memory allocation failure in these functions.
>>>
>>> This issue was detected by using the Coccinelle software.
>>>
>>> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
>>> ---
>>
>> nak, unlike many others, these message give extra info on which
>> allocation failed, that can be useful.
> 
> <shrug>  Not really.  There are tradeoffs.
> 
> There is the generic stack dump on OOM so the module/line
> is already known.
> 

If that is the case then I have no strong feelings either way.

> The existence of these messages increases code size which
> also make the OOM condition slightly more likely.
> 
> These are generally used only at initialization and those
> if you are OOM at initialization, bad things happen anyway
> so where the specific OOM occurred doesn't really matter.
> 

True, these messages will probably only ever get displayed if someone is
messing with the allocated structs and accidentally balloons their size,
so these are more debug statements than anything.

> Markus' commit messages are always really poor descriptions
> of why these removals are somewhat useful and the commit
> could/should/might be applied.
> 
> Your choice.
> 
>>>  drivers/video/fbdev/omap2/omapfb/dss/dispc.c    | 4 +---
>>>  drivers/video/fbdev/omap2/omapfb/dss/dss.c      | 4 +---
>>>  drivers/video/fbdev/omap2/omapfb/dss/hdmi_phy.c | 4 +---
>>>  3 files changed, 3 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/drivers/video/fbdev/omap2/omapfb/dss/dispc.c b/drivers/video/fbdev/omap2/omapfb/dss/dispc.c
>>> index 7a75dfda9845..10164a3bae4a 100644
>>> --- a/drivers/video/fbdev/omap2/omapfb/dss/dispc.c
>>> +++ b/drivers/video/fbdev/omap2/omapfb/dss/dispc.c
>>> @@ -3982,10 +3982,8 @@ static int dispc_init_features(struct platform_device *pdev)
>>>  	struct dispc_features *dst;
>>>  
>>>  	dst = devm_kzalloc(&pdev->dev, sizeof(*dst), GFP_KERNEL);
>>> -	if (!dst) {
>>> -		dev_err(&pdev->dev, "Failed to allocate DISPC Features\n");
>>> +	if (!dst)
>>>  		return -ENOMEM;
>>> -	}
>>>  
>>>  	switch (omapdss_get_version()) {
>>>  	case OMAPDSS_VER_OMAP24xx:
>>> diff --git a/drivers/video/fbdev/omap2/omapfb/dss/dss.c b/drivers/video/fbdev/omap2/omapfb/dss/dss.c
>>> index 48c6500c24e1..a5de13777e2b 100644
>>> --- a/drivers/video/fbdev/omap2/omapfb/dss/dss.c
>>> +++ b/drivers/video/fbdev/omap2/omapfb/dss/dss.c
>>> @@ -893,10 +893,8 @@ static int dss_init_features(struct platform_device *pdev)
>>>  	struct dss_features *dst;
>>>  
>>>  	dst = devm_kzalloc(&pdev->dev, sizeof(*dst), GFP_KERNEL);
>>> -	if (!dst) {
>>> -		dev_err(&pdev->dev, "Failed to allocate local DSS Features\n");
>>> +	if (!dst)
>>>  		return -ENOMEM;
>>> -	}
>>>  
>>>  	switch (omapdss_get_version()) {
>>>  	case OMAPDSS_VER_OMAP24xx:
>>> diff --git a/drivers/video/fbdev/omap2/omapfb/dss/hdmi_phy.c b/drivers/video/fbdev/omap2/omapfb/dss/hdmi_phy.c
>>> index 9a13c35fd6d8..d25eea10c665 100644
>>> --- a/drivers/video/fbdev/omap2/omapfb/dss/hdmi_phy.c
>>> +++ b/drivers/video/fbdev/omap2/omapfb/dss/hdmi_phy.c
>>> @@ -195,10 +195,8 @@ static int hdmi_phy_init_features(struct platform_device *pdev)
>>>  	const struct hdmi_phy_features *src;
>>>  
>>>  	dst = devm_kzalloc(&pdev->dev, sizeof(*dst), GFP_KERNEL);
>>> -	if (!dst) {
>>> -		dev_err(&pdev->dev, "Failed to allocate HDMI PHY Features\n");
>>> +	if (!dst)
>>>  		return -ENOMEM;
>>> -	}
>>>  
>>>  	switch (omapdss_get_version()) {
>>>  	case OMAPDSS_VER_OMAP4430_ES1:
>>>