linux-kernel - Re: [PATCH] staging: exfat: add exfat filesystem code to staging

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Message-ID: <20190830084333.GA193084@architecture4>
Date:   Fri, 30 Aug 2019 16:43:33 +0800
From:   Gao Xiang <gaoxiang25@...wei.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
CC:     <devel@...verdev.osuosl.org>,
        Christoph Hellwig <hch@...radead.org>,
        Valdis Klētnieks <valdis.kletnieks@...edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        <linux-kernel@...r.kernel.org>,
        Sasha Levin <alexander.levin@...rosoft.com>,
        <linux-fsdevel@...r.kernel.org>,
        "OGAWA Hirofumi" <hirofumi@...l.parknet.co.jp>
Subject: Re: [PATCH] staging: exfat: add exfat filesystem code to staging

Hi Dan,

On Fri, Aug 30, 2019 at 11:34:45AM +0300, Dan Carpenter wrote:
> On Fri, Aug 30, 2019 at 12:04:41AM +0800, Gao Xiang wrote:
> > Anyway, I'm fine to delete them all if you like, but I think majority of these
> > are meaningful.
> > 
> > data.c-		/* page is already locked */
> > data.c-		DBG_BUGON(PageUptodate(page));
> > data.c-
> > data.c:		if (unlikely(err))
> > data.c-			SetPageError(page);
> > data.c-		else
> > data.c-			SetPageUptodate(page);
> 
> If we cared about speed here then we would delete the DBG_BUGON() check
> because that's going to be expensive.  The likely/unlikely annotations
> should be used in places a reasonable person thinks it will make a
> difference to benchmarks.

DBG_BUGON will be a no-op ((void)x) in non-debugging mode,
I discussed related stuffs with Greg many months before [1] and
other filesystems also have similar functions...

p.s. I think we come to an agreement here...
I killed all unlikely/likely.

[1] http://driverdev.linuxdriverproject.org/pipermail/driverdev-devel/2018-November/128951.html
sorry about no lore here.

Thanks,
Gao Xiang

> 
> regards,
> dan carpenter
>