linux-kernel - Re: [PATCH v5 04/22] cachefiles: notify user daemon with anon

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Message-ID: <1029248.1647871294@warthog.procyon.org.uk>
Date:   Mon, 21 Mar 2022 14:01:34 +0000
From:   David Howells <dhowells@...hat.com>
To:     Jeffle Xu <jefflexu@...ux.alibaba.com>
Cc:     dhowells@...hat.com, linux-cachefs@...hat.com, xiang@...nel.org,
        chao@...nel.org, linux-erofs@...ts.ozlabs.org,
        torvalds@...ux-foundation.org, gregkh@...uxfoundation.org,
        willy@...radead.org, linux-fsdevel@...r.kernel.org,
        joseph.qi@...ux.alibaba.com, bo.liu@...ux.alibaba.com,
        tao.peng@...ux.alibaba.com, gerry@...ux.alibaba.com,
        eguan@...ux.alibaba.com, linux-kernel@...r.kernel.org,
        luodaowen.backend@...edance.com
Subject: Re: [PATCH v5 04/22] cachefiles: notify user daemon with anon_fd when looking up cookie

Jeffle Xu <jefflexu@...ux.alibaba.com> wrote:

> +	read_lock(&cache->reqs_lock);
> +
> +	/* recheck dead state under lock */
> +	if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
> +		read_unlock(&cache->reqs_lock);
> +		ret = -EIO;
> +		goto out;
> +	}
> +
> +	xa_lock(xa);
> +	ret = __xa_alloc(xa, &id, req, xa_limit_32b, GFP_KERNEL);

You're holding a spinlock.  You can't use GFP_KERNEL.

> +static int cachefiles_ondemand_cinit(struct cachefiles_cache *cache, char *args)
> +{
> ...
> +	tmp = kstrdup(args, GFP_KERNEL);

No need to copy the string.  The caller already did that and added a NUL for
good measure.

I would probably move most of the functions added in this patch to
fs/cachefiles/ondemand.c.

David