From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58580) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZhDLC-0001vJ-8Z for qemu-devel@nongnu.org; Wed, 30 Sep 2015 05:06:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZhDL7-0006pV-0O for qemu-devel@nongnu.org; Wed, 30 Sep 2015 05:06:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37222) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZhDL6-0006pJ-Ey for qemu-devel@nongnu.org; Wed, 30 Sep 2015 05:06:16 -0400 Date: Wed, 30 Sep 2015 12:06:10 +0300 From: "Michael S. Tsirkin" Message-ID: <20150930090610.GA3141@redhat.com> References: <1443544494-28737-1-git-send-email-marcandre.lureau@redhat.com> <1443544494-28737-6-git-send-email-marcandre.lureau@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1443544494-28737-6-git-send-email-marcandre.lureau@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v6 05/24] util: add memfd helpers List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: marcandre.lureau@redhat.com Cc: haifeng.lin@huawei.com, thibaut.collet@6wind.com, jasowang@redhat.com, qemu-devel@nongnu.org, pbonzini@redhat.com On Tue, Sep 29, 2015 at 06:34:35PM +0200, marcandre.lureau@redhat.com wro= te: > From: Marc-Andr=E9 Lureau >=20 > Add qemu_memfd_alloc/free() helpers. >=20 > The function helps to allocate and seal a memfd. >=20 > Signed-off-by: Marc-Andr=E9 Lureau > --- > include/qemu/memfd.h | 4 ++++ > util/memfd.c | 59 ++++++++++++++++++++++++++++++++++++++++++++= ++++++-- > 2 files changed, 61 insertions(+), 2 deletions(-) >=20 > diff --git a/include/qemu/memfd.h b/include/qemu/memfd.h > index 8b1fe6a..950fb88 100644 > --- a/include/qemu/memfd.h > +++ b/include/qemu/memfd.h > @@ -17,4 +17,8 @@ > #define F_SEAL_WRITE 0x0008 /* prevent writes */ > #endif > =20 > +void *qemu_memfd_alloc(const char *name, size_t size, unsigned int sea= ls, > + int *fd); > +void qemu_memfd_free(void *ptr, size_t size, int fd); > + > #endif /* QEMU_MEMFD_H */ > diff --git a/util/memfd.c b/util/memfd.c > index a98d57e..3168902 100644 > --- a/util/memfd.c > +++ b/util/memfd.c > @@ -27,6 +27,14 @@ > =20 > #include "config-host.h" > =20 > +#include > +#include > + > +#include > +#include > +#include > +#include > + > #include "qemu/memfd.h" > =20 > #ifdef CONFIG_MEMFD > @@ -44,13 +52,60 @@ > #define MFD_ALLOW_SEALING 0x0002U > #endif > =20 > -static inline int memfd_create(const char *name, unsigned int flags) > +static int memfd_create(const char *name, unsigned int flags) > { > return syscall(__NR_memfd_create, name, flags); > } > #else /* !LINUX */ > -static inline int memfd_create(const char *name, unsigned int flags) > +static int memfd_create(const char *name, unsigned int flags) > { > return -1; > } > #endif > + > +void *qemu_memfd_alloc(const char *name, size_t size, unsigned int sea= ls, > + int *fd) > +{ > + void *ptr; > + int mfd; > + > + *fd =3D -1; > + mfd =3D memfd_create(name, MFD_ALLOW_SEALING | MFD_CLOEXEC); > + if (mfd !=3D -1) { > + if (ftruncate(mfd, size) =3D=3D -1) { > + perror("ftruncate"); > + close(mfd); > + return NULL; > + } > + > + if (fcntl(mfd, F_ADD_SEALS, seals) =3D=3D -1) { > + perror("fcntl"); > + close(mfd); > + return NULL; > + } Why do it here? I note that you don't try to do this with the tmpfs fallback. > + } else { > + perror("memfd"); > + return NULL; > + } > + > + ptr =3D mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, mfd, 0); > + if (ptr =3D=3D MAP_FAILED) { > + perror("mmap"); > + close(mfd); > + return NULL; > + } > + > + *fd =3D mfd; > + return ptr; > +} > + > +void qemu_memfd_free(void *ptr, size_t size, int fd) > +{ > + if (ptr) { > + munmap(ptr, size); > + } > + > + if (fd !=3D -1) { > + close(fd); > + } > +} > --=20 > 2.4.3