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Wed, 16 Dec 2020 17:12:16 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 5C191AC7F; Wed, 16 Dec 2020 17:12:15 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: ba015c2c-2d2e-4928-971b-296d855c24e6 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1608138735; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=JyoICodWswFOjhkfImLaYWuoNHW5VwMCeyaAzQoPIVY=; b=E2ovRRhDq8qZA6ADoDLBDC84/LosqcHTTNZz3rhuOzf1Nu2znr0k74INyOaHAUqzgx/VO1 kMywhfbVajrodQnJ6H6F0AngQ4gOwzxjAocwtE1s/GoIHHsGgkRpHPpsuxkq6SDXzji9Fm tdOOq2eLTxgjmJtMfaq6FOcloiVugTo= Subject: Re: [PATCH v3 3/8] xen/hypfs: add new enter() and exit() per node callbacks To: Jan Beulich Cc: Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Wei Liu , xen-devel@lists.xenproject.org References: <20201209160956.32456-1-jgross@suse.com> <20201209160956.32456-4-jgross@suse.com> <36469295-8c77-0e58-654a-35fd992c11a1@suse.com> <227825e7-d704-fd36-a327-1dbd6aa391c8@suse.com> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <6b0cda5f-596f-f390-c22b-c922dee04a55@suse.com> Date: Wed, 16 Dec 2020 18:12:14 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <227825e7-d704-fd36-a327-1dbd6aa391c8@suse.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="diajpoYnltilczuPMwLTp2FoHHS9ZxUM9" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --diajpoYnltilczuPMwLTp2FoHHS9ZxUM9 Content-Type: multipart/mixed; boundary="2jEMZxHgzjF8ZuqZQnmYb1JUL8Mq3hJGs"; protected-headers="v1" From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= To: Jan Beulich Cc: Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Wei Liu , xen-devel@lists.xenproject.org Message-ID: <6b0cda5f-596f-f390-c22b-c922dee04a55@suse.com> Subject: Re: [PATCH v3 3/8] xen/hypfs: add new enter() and exit() per node callbacks References: <20201209160956.32456-1-jgross@suse.com> <20201209160956.32456-4-jgross@suse.com> <36469295-8c77-0e58-654a-35fd992c11a1@suse.com> <227825e7-d704-fd36-a327-1dbd6aa391c8@suse.com> In-Reply-To: <227825e7-d704-fd36-a327-1dbd6aa391c8@suse.com> --2jEMZxHgzjF8ZuqZQnmYb1JUL8Mq3hJGs Content-Type: multipart/mixed; boundary="------------65F4E64037C290A0B9B4D7C9" Content-Language: en-US This is a multi-part message in MIME format. --------------65F4E64037C290A0B9B4D7C9 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 16.12.20 17:36, Jan Beulich wrote: > On 16.12.2020 17:24, J=C3=BCrgen Gro=C3=9F wrote: >> On 16.12.20 17:16, Jan Beulich wrote: >>> On 09.12.2020 17:09, Juergen Gross wrote: >>>> In order to better support resource allocation and locking for dynam= ic >>>> hypfs nodes add enter() and exit() callbacks to struct hypfs_funcs. >>>> >>>> The enter() callback is called when entering a node during hypfs use= r >>>> actions (traversing, reading or writing it), while the exit() callba= ck >>>> is called when leaving a node (accessing another node at the same or= a >>>> higher directory level, or when returning to the user). >>>> >>>> For avoiding recursion this requires a parent pointer in each node. >>>> Let the enter() callback return the entry address which is stored as= >>>> the last accessed node in order to be able to use a template entry f= or >>>> that purpose in case of dynamic entries. >>>> >>>> Signed-off-by: Juergen Gross >>>> --- >>>> V2: >>>> - new patch >>>> >>>> V3: >>>> - add ASSERT(entry); (Jan Beulich) >>>> >>>> Signed-off-by: Juergen Gross >>>> --- >>>> xen/common/hypfs.c | 80 ++++++++++++++++++++++++++++++++++++= +++++ >>>> xen/include/xen/hypfs.h | 5 +++ >>>> 2 files changed, 85 insertions(+) >>>> >>>> diff --git a/xen/common/hypfs.c b/xen/common/hypfs.c >>>> index 6f822ae097..f04934db10 100644 >>>> --- a/xen/common/hypfs.c >>>> +++ b/xen/common/hypfs.c >>>> @@ -25,30 +25,40 @@ CHECK_hypfs_dirlistentry; >>>> ROUNDUP((name_len) + 1, alignof(struct xen_hypfs_direntry)))= >>>> =20 >>>> const struct hypfs_funcs hypfs_dir_funcs =3D { >>>> + .enter =3D hypfs_node_enter, >>>> + .exit =3D hypfs_node_exit, >>>> .read =3D hypfs_read_dir, >>>> .write =3D hypfs_write_deny, >>>> .getsize =3D hypfs_getsize, >>>> .findentry =3D hypfs_dir_findentry, >>>> }; >>>> const struct hypfs_funcs hypfs_leaf_ro_funcs =3D { >>>> + .enter =3D hypfs_node_enter, >>>> + .exit =3D hypfs_node_exit, >>>> .read =3D hypfs_read_leaf, >>>> .write =3D hypfs_write_deny, >>>> .getsize =3D hypfs_getsize, >>>> .findentry =3D hypfs_leaf_findentry, >>>> }; >>>> const struct hypfs_funcs hypfs_leaf_wr_funcs =3D { >>>> + .enter =3D hypfs_node_enter, >>>> + .exit =3D hypfs_node_exit, >>>> .read =3D hypfs_read_leaf, >>>> .write =3D hypfs_write_leaf, >>>> .getsize =3D hypfs_getsize, >>>> .findentry =3D hypfs_leaf_findentry, >>>> }; >>>> const struct hypfs_funcs hypfs_bool_wr_funcs =3D { >>>> + .enter =3D hypfs_node_enter, >>>> + .exit =3D hypfs_node_exit, >>>> .read =3D hypfs_read_leaf, >>>> .write =3D hypfs_write_bool, >>>> .getsize =3D hypfs_getsize, >>>> .findentry =3D hypfs_leaf_findentry, >>>> }; >>>> const struct hypfs_funcs hypfs_custom_wr_funcs =3D { >>>> + .enter =3D hypfs_node_enter, >>>> + .exit =3D hypfs_node_exit, >>>> .read =3D hypfs_read_leaf, >>>> .write =3D hypfs_write_custom, >>>> .getsize =3D hypfs_getsize, >>>> @@ -63,6 +73,8 @@ enum hypfs_lock_state { >>>> }; >>>> static DEFINE_PER_CPU(enum hypfs_lock_state, hypfs_locked); >>>> =20 >>>> +static DEFINE_PER_CPU(const struct hypfs_entry *, hypfs_last_node_e= ntered); >>>> + >>>> HYPFS_DIR_INIT(hypfs_root, ""); >>>> =20 >>>> static void hypfs_read_lock(void) >>>> @@ -100,11 +112,59 @@ static void hypfs_unlock(void) >>>> } >>>> } >>>> =20 >>>> +const struct hypfs_entry *hypfs_node_enter(const struct hypfs_entry= *entry) >>>> +{ >>>> + return entry; >>>> +} >>>> + >>>> +void hypfs_node_exit(const struct hypfs_entry *entry) >>>> +{ >>>> +} >>>> + >>>> +static int node_enter(const struct hypfs_entry *entry) >>>> +{ >>>> + const struct hypfs_entry **last =3D &this_cpu(hypfs_last_node_e= ntered); >>>> + >>>> + entry =3D entry->funcs->enter(entry); >>>> + if ( IS_ERR(entry) ) >>>> + return PTR_ERR(entry); >>>> + >>>> + ASSERT(entry); >>>> + ASSERT(!*last || *last =3D=3D entry->parent); >>>> + >>>> + *last =3D entry; >>>> + >>>> + return 0; >>>> +} >>>> + >>>> +static void node_exit(const struct hypfs_entry *entry) >>>> +{ >>>> + const struct hypfs_entry **last =3D &this_cpu(hypfs_last_node_e= ntered); >>>> + >>>> + if ( !*last ) >>>> + return; >>> >>> To my question regarding this in v2 you replied >>> >>> "I rechecked and have found that this was a remnant from an earlier >>> variant. *last won't ever be NULL, so the if can be dropped (a NUL= L >>> will be catched by the following ASSERT())." >>> >>> Now this if() is still there. Why? >> >> I really thought I did remove the if(). Seems as if I did that on >> my test machine only and not in my git tree. Sorry for that. >=20 > So should I drop it while committing and adding > Reviewed-by: Jan Beulich > ? Yes, please. 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