From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: passt.top; dkim=pass (2048-bit key; secure) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.a=rsa-sha256 header.s=202508 header.b=nXM2+cZN; dkim-atps=neutral Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) by passt.top (Postfix) with ESMTPS id E5C455A0279 for ; Fri, 15 Aug 2025 03:11:43 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202508; t=1755220300; bh=3Xepr3yxwXPWB1QrufxwFLqJp03rIEX6YnOM3GE55MQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nXM2+cZN2aSn1+4rnb/Jmt8dFIejtjEau5D2hB99+u6+EIjr1yZ58IlECWk98CwkO eJFLj4Jx6Ofh08XLLwBguDh3ovcfpxYwp8WYI5hzKgDnyKyMy61m9sdo4zM1NYvr0W ditYOPLwKEHmqDu224b7/TC5FOZ5HUOzVx3opE02CrSebdgEoqNeYCWFHJOLxc9aec bhP0MEfhtQqfKPB69Ss9/r7X0R9oAlguN70vImBrcv14EM4ePj3AJCco7UCEeM3nQU MpKTuYr+lkRHsl+00GmrWsVhYLIJvHR1zyLTJP9qUDHHivdd7Uwck9C3CkxvCLJX4t IQINtpTKJAr7w== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4c33wX4kvxz4xcr; Fri, 15 Aug 2025 11:11:40 +1000 (AEST) Date: Fri, 15 Aug 2025 11:01:21 +1000 From: David Gibson To: Laurent Vivier Subject: Re: [PATCH v10 03/30] iov: Update IOV_REMOVE_HEADER() and IOV_PEEK_HEADER() Message-ID: References: <20250814094849.919709-1-lvivier@redhat.com> <20250814094849.919709-4-lvivier@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="F+cLtfCpRD2ZzPnw" Content-Disposition: inline In-Reply-To: <20250814094849.919709-4-lvivier@redhat.com> Message-ID-Hash: OJBABAIS2KHXWIZXTT2HENIHNWWSA56D X-Message-ID-Hash: OJBABAIS2KHXWIZXTT2HENIHNWWSA56D X-MailFrom: dgibson@gandalf.ozlabs.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: passt-dev@passt.top X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --F+cLtfCpRD2ZzPnw Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Aug 14, 2025 at 11:48:22AM +0200, Laurent Vivier wrote: > Provide a temporary variable of the wanted type to store > the header if the memory in the iovec array is not contiguous. >=20 > Signed-off-by: Laurent Vivier Reviewed-by: David Gibson > --- > iov.c | 53 ++++++++++++++++++++++++++++++++++++++++++++--------- > iov.h | 35 +++++++++++++++++++++-------------- > tcp_buf.c | 2 +- > 3 files changed, 66 insertions(+), 24 deletions(-) >=20 > diff --git a/iov.c b/iov.c > index 9a91eb63026a..d20fbb854933 100644 > --- a/iov.c > +++ b/iov.c > @@ -109,7 +109,7 @@ size_t iov_from_buf(const struct iovec *iov, size_t i= ov_cnt, > * > * Return: the number of bytes successfully copied. > */ > -/* cppcheck-suppress unusedFunction */ > +/* cppcheck-suppress [staticFunction] */ > size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt, > size_t offset, void *buf, size_t bytes) > { > @@ -127,6 +127,7 @@ size_t iov_to_buf(const struct iovec *iov, size_t iov= _cnt, > /* copying data */ > for (copied =3D 0; copied < bytes && i < iov_cnt; i++) { > size_t len =3D MIN(iov[i].iov_len - offset, bytes - copied); > + ASSERT(iov[i].iov_base); > memcpy((char *)buf + copied, (char *)iov[i].iov_base + offset, > len); > copied +=3D len; > @@ -208,7 +209,7 @@ bool iov_drop_header(struct iov_tail *tail, size_t le= n) > } > =20 > /** > - * iov_peek_header_() - Get pointer to a header from an IOV tail > + * iov_check_header() - Check if a header can be accessed > * @tail: IOV tail to get header from > * @len: Length of header to get, in bytes > * @align: Required alignment of header, in bytes > @@ -219,8 +220,7 @@ bool iov_drop_header(struct iov_tail *tail, size_t le= n) > * overruns the IO vector, is not contiguous or doesn't have the > * requested alignment. > */ > -/* cppcheck-suppress [staticFunction,unmatchedSuppression] */ > -void *iov_peek_header_(struct iov_tail *tail, size_t len, size_t align) > +static void *iov_check_header(struct iov_tail *tail, size_t len, size_t = align) > { > char *p; > =20 > @@ -240,27 +240,62 @@ void *iov_peek_header_(struct iov_tail *tail, size_= t len, size_t align) > return p; > } > =20 > +/** > + * iov_peek_header_() - Get pointer to a header from an IOV tail > + * @tail: IOV tail to get header from > + * @v: Temporary memory to use if the memory in @tail > + * is discontinuous > + * @len: Length of header to get, in bytes > + * @align: Required alignment of header, in bytes > + * > + * @tail may be pruned, but will represent the same bytes as before. > + * > + * Return: pointer to the first @len logical bytes of the tail, or to > + * a copy if that overruns the IO vector, is not contiguous or > + * doesn't have the requested alignment. NULL if that overruns t= he > + * IO vector. > + */ > +/* cppcheck-suppress [staticFunction,unmatchedSuppression] */ > +void *iov_peek_header_(struct iov_tail *tail, void *v, size_t len, size_= t align) > +{ > + char *p =3D iov_check_header(tail, len, align); > + size_t l; > + > + if (p) > + return p; > + > + l =3D iov_to_buf(tail->iov, tail->cnt, tail->off, v, len); > + if (l !=3D len) > + return NULL; > + > + return v; > +} > + > /** > * iov_remove_header_() - Remove a header from an IOV tail > * @tail: IOV tail to remove header from (modified) > + * @v: Temporary memory to use if the memory in @tail > + * is discontinuous > * @len: Length of header to remove, in bytes > * @align: Required alignment of header, in bytes > * > * On success, @tail is updated so that it longer includes the bytes of = the > * returned header. > * > - * Return: pointer to the first @len logical bytes of the tail, NULL if = that > - * overruns the IO vector, is not contiguous or doesn't have the > - * requested alignment. > + * Return: pointer to the first @len logical bytes of the tail, or to > + * a copy if that overruns the IO vector, is not contiguous or > + * doesn't have the requested alignment. NULL if that overruns t= he > + * IO vector. > */ > -void *iov_remove_header_(struct iov_tail *tail, size_t len, size_t align) > +void *iov_remove_header_(struct iov_tail *tail, void *v, size_t len, siz= e_t align) > { > - char *p =3D iov_peek_header_(tail, len, align); > + char *p =3D iov_peek_header_(tail, v, len, align); > =20 > if (!p) > return NULL; > =20 > tail->off =3D tail->off + len; > + > return p; > } > =20 > diff --git a/iov.h b/iov.h > index c94fabe1eb43..1821b40b1cb5 100644 > --- a/iov.h > +++ b/iov.h > @@ -73,38 +73,45 @@ struct iov_tail { > bool iov_tail_prune(struct iov_tail *tail); > size_t iov_tail_size(struct iov_tail *tail); > bool iov_drop_header(struct iov_tail *tail, size_t len); > -void *iov_peek_header_(struct iov_tail *tail, size_t len, size_t align); > -void *iov_remove_header_(struct iov_tail *tail, size_t len, size_t align= ); > +void *iov_peek_header_(struct iov_tail *tail, void *v, size_t len, size_= t align); > +void *iov_remove_header_(struct iov_tail *tail, void *v, size_t len, siz= e_t align); > ssize_t iov_tail_clone(struct iovec *dst_iov, size_t dst_iov_cnt, > struct iov_tail *tail); > =20 > /** > * IOV_PEEK_HEADER() - Get typed pointer to a header from an IOV tail > * @tail_: IOV tail to get header from > - * @type_: Data type of the header > + * @var_: Temporary buffer of the type of the header to use if > + * the memory in the iovec array is not contiguous. > * > * @tail_ may be pruned, but will represent the same bytes as before. > * > - * Return: pointer of type (@type_ *) located at the start of @tail_, NU= LL if > - * we can't get a contiguous and aligned pointer. > + * Return: pointer of type (@type_ *) located at the start of @tail_ > + * or to @var_ if iovec memory is not contiguous, NULL if > + * that overruns the iovec. > */ > -#define IOV_PEEK_HEADER(tail_, type_) \ > - ((type_ *)(iov_peek_header_((tail_), \ > - sizeof(type_), __alignof__(type_)))) > + > +#define IOV_PEEK_HEADER(tail_, var_) \ > + ((__typeof__(var_) *)(iov_peek_header_((tail_), &(var_), \ > + sizeof(var_), \ > + __alignof__(var_)))) > =20 > /** > * IOV_REMOVE_HEADER() - Remove and return typed header from an IOV tail > * @tail_: IOV tail to remove header from (modified) > - * @type_: Data type of the header to remove > + * @var_: Temporary buffer of the type of the header to use if > + * the memory in the iovec array is not contiguous. > * > * On success, @tail_ is updated so that it longer includes the bytes of= the > * returned header. > * > - * Return: pointer of type (@type_ *) located at the old start of @tail_= , NULL > - * if we can't get a contiguous and aligned pointer. > + * Return: pointer of type (@type_ *) located at the start of @tail_ > + * or to @var_ if iovec memory is not contiguous, NULL if > + * that overruns the iovec. > */ > -#define IOV_REMOVE_HEADER(tail_, type_) \ > - ((type_ *)(iov_remove_header_((tail_), \ > - sizeof(type_), __alignof__(type_)))) > + > +#define IOV_REMOVE_HEADER(tail_, var_) \ > + ((__typeof__(var_) *)(iov_remove_header_((tail_), &(var_), \ > + sizeof(var_), __alignof__(var_)))) > =20 > #endif /* IOVEC_H */ > diff --git a/tcp_buf.c b/tcp_buf.c > index d1fca676c9a7..bc898de86919 100644 > --- a/tcp_buf.c > +++ b/tcp_buf.c > @@ -160,7 +160,7 @@ static void tcp_l2_buf_fill_headers(const struct tcp_= tap_conn *conn, > uint32_t seq, bool no_tcp_csum) > { > struct iov_tail tail =3D IOV_TAIL(&iov[TCP_IOV_PAYLOAD], 1, 0); > - struct tcphdr *th =3D IOV_REMOVE_HEADER(&tail, struct tcphdr); > + struct tcphdr th_storage, *th =3D IOV_REMOVE_HEADER(&tail, th_storage); > struct tap_hdr *taph =3D iov[TCP_IOV_TAP].iov_base; > const struct flowside *tapside =3D TAPFLOW(conn); > const struct in_addr *a4 =3D inany_v4(&tapside->oaddr); --=20 David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson --F+cLtfCpRD2ZzPnw Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEO+dNsU4E3yXUXRK2zQJF27ox2GcFAmiehs8ACgkQzQJF27ox 2GfPdQ//aE5T3hropNyqsfkETp1Aek3AY3mOTXfDl62fuz9Pc4FXBMJNT4bYD3Sq YcK2u7in9TrKrijrYxi5M51Brevwb8y4dofr3Vq/FNq/LFwkGIxICWkrWYB77h5W UYN6Kr0QSlEHOt97BvlxKtjcVoy6NKNm8jSaMtx0HbXIG+tccDZvW257I69FkE09 BYjBeumEc0dwT5XcEVOAOfpl7Gs4H9V+a+zd9c8QYVwPTNxcZ0ze4BJ7yPXmyoq7 +nDfn4WlyzB9TZPDmlaltNy2RrH9bho57s2DnMWCEe6zW7sfsMBqZWu/AmR28cU4 0A46tFib6ec/rK6n9MCnoCu7m4g2rxvBvj9urn1KhcpWlZ9wgp53CaJSY9bXZEH8 T0LXCxs9F5AKvPYnGOJsvjw+Q3nDKKXEGbyeYFSTB4VXG5Dphrg91adtBksu3N+B tR4RmjpJqEIxCxTWynvvJ+n37d2fuieSQi2K7lgzLZkIO+U0pOMUaqrDprbXWci4 xIJSi/ieGiI5zp9fF4Z2f19MS4CICj6/wsu8drrdkgM538yQwop/Bh5YQIVjOURr uEo2QtnQXT89KYTyvpw47CWQ3KtEvYZ2TJJ0A9cbCy0aaWHfjvYMhDpd4UYzNmuz OicPXwji+AGTkmaK5L+brVP+Fwohyuu4dLAd9uV5xFMhKvVsN3c= =QSga -----END PGP SIGNATURE----- --F+cLtfCpRD2ZzPnw--