linux-kernel - Re: [PATCH 22/60] staging: lustre: fid: fix race in fid allocation

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Message-ID: <20170131085542.GI6881@mwanda>
Date:   Tue, 31 Jan 2017 11:55:42 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     James Simmons <jsimmons@...radead.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devel@...verdev.osuosl.org,
        Andreas Dilger <andreas.dilger@...el.com>,
        Oleg Drokin <oleg.drokin@...el.com>,
        Fan Yong <fan.yong@...el.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Lustre Development List <lustre-devel@...ts.lustre.org>
Subject: Re: [PATCH 22/60] staging: lustre: fid: fix race in fid allocation

On Sat, Jan 28, 2017 at 07:04:50PM -0500, James Simmons wrote:
> -		if (!fid_is_zero(&seq->lcs_fid) &&
> -		    fid_oid(&seq->lcs_fid) < seq->lcs_width) {
> +		if (unlikely(!fid_is_zero(&seq->lcs_fid) &&
> +			     fid_oid(&seq->lcs_fid) < seq->lcs_width)) {

What does adding an unlikely have to do with the race condition?  Also
only add likely/unlikely when it makes a difference to benchmarks.
Otherwise leave it out.

>  			/* Just bump last allocated fid and return to caller. */
> -			seq->lcs_fid.f_oid += 1;
> +			seq->lcs_fid.f_oid++;

Ok...  I'm pretty sure the compiler can figure this out on its own.
Stop mixing white space changes into your bug fixes.  It just makes
reviewing more complicated.

>  			rc = 0;
>  			break;
>  		}
>  

regards,
dan carpenter