linux-kernel - Re: [PATCH v3 2/2] net/9p: add a per-client fcall kmem

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Date:   Fri, 10 Aug 2018 03:41:47 +0200
From:   Dominique Martinet <asmadeus@...ewreck.org>
To:     piaojun <piaojun@...wei.com>
Cc:     v9fs-developer@...ts.sourceforge.net,
        Dominique Martinet <dominique.martinet@....fr>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Matthew Wilcox <willy@...radead.org>,
        Greg Kurz <groug@...d.org>
Subject: Re: [PATCH v3 2/2] net/9p: add a per-client fcall kmem_cache

piaojun wrote on Fri, Aug 10, 2018:
> Could you help paste the test result of before-after-applied this patch in
> comment? And please see my comments below.

Thanks the the review, do you mean the commit message?

I'll add the summary I wrote in reply to your question a few mails
before.


> > diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h
> > index e23896116d9a..645266b74652 100644
> > --- a/include/net/9p/9p.h
> > +++ b/include/net/9p/9p.h
> > @@ -336,6 +336,9 @@ enum p9_qid_t {
> >  #define P9_NOFID	(u32)(~0)
> >  #define P9_MAXWELEM	16
> >  
> > +/* Minimal header size: len + id + tag */
> 
> Here should be 'size + id + tag'.

hm I didn't want to repeat size, but I guess people do refer to that
field as size.
I'll actually rewrite it as:
 Minimal header size: size[4] type[1] tag[2]

> > +	kmem_cache_destroy(clnt->fcall_cache);
> 
> I'm afraid that we should check NULL for clnt->fcall_cache.

kmem_cache_destroy() in mm/slab_common.c does the null check for us:
------
void kmem_cache_destroy(struct kmem_cache *s)
{
        int err;
        
        if (unlikely(!s))
                return;
------

-- 
Dominique