From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36678) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eEIt1-0005Zk-7r for qemu-devel@nongnu.org; Mon, 13 Nov 2017 12:51:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eEIt0-0003eY-Bc for qemu-devel@nongnu.org; Mon, 13 Nov 2017 12:51:07 -0500 References: <20171113162053.58795-1-vsementsov@virtuozzo.com> <20171113162053.58795-2-vsementsov@virtuozzo.com> From: Eric Blake Message-ID: <12463b01-41eb-4d17-65c0-a94de499e753@redhat.com> Date: Mon, 13 Nov 2017 11:50:50 -0600 MIME-Version: 1.0 In-Reply-To: <20171113162053.58795-2-vsementsov@virtuozzo.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="bpAfEjNjU9Ku4HeajLlJPcTqiBTBxIOkV" Subject: Re: [Qemu-devel] [PATCH 1/4 for-2.11?] block/dirty-bitmap: add lock to bdrv_enable/disable_dirty_bitmap List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: mreitz@redhat.com, kwolf@redhat.com, jsnow@redhat.com, famz@redhat.com, stefanha@redhat.com, armbru@redhat.com, pbonzini@redhat.com, den@openvz.org, nshirokovskiy@virtuozzo.com, mnestratov@virtuozzo.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --bpAfEjNjU9Ku4HeajLlJPcTqiBTBxIOkV From: Eric Blake To: Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: mreitz@redhat.com, kwolf@redhat.com, jsnow@redhat.com, famz@redhat.com, stefanha@redhat.com, armbru@redhat.com, pbonzini@redhat.com, den@openvz.org, nshirokovskiy@virtuozzo.com, mnestratov@virtuozzo.com Message-ID: <12463b01-41eb-4d17-65c0-a94de499e753@redhat.com> Subject: Re: [PATCH 1/4 for-2.11?] block/dirty-bitmap: add lock to bdrv_enable/disable_dirty_bitmap References: <20171113162053.58795-1-vsementsov@virtuozzo.com> <20171113162053.58795-2-vsementsov@virtuozzo.com> In-Reply-To: <20171113162053.58795-2-vsementsov@virtuozzo.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 11/13/2017 10:20 AM, Vladimir Sementsov-Ogievskiy wrote: > Like other setters here these functions should take a lock. >=20 > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > block/dirty-bitmap.c | 4 ++++ > 1 file changed, 4 insertions(+) Should this patch be in 2.11? >=20 > diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c > index bd04e991b1..2a0bcd9e51 100644 > --- a/block/dirty-bitmap.c > +++ b/block/dirty-bitmap.c > @@ -397,15 +397,19 @@ void bdrv_remove_persistent_dirty_bitmap(BlockDri= verState *bs, > /* Called with BQL taken. */ > void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap) > { > + bdrv_dirty_bitmap_lock(bitmap); > assert(!bdrv_dirty_bitmap_frozen(bitmap)); > bitmap->disabled =3D true; > + bdrv_dirty_bitmap_unlock(bitmap); Why do we need this lock in addition to BQL? > } > =20 > /* Called with BQL taken. */ > void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap) > { > + bdrv_dirty_bitmap_lock(bitmap); > assert(!bdrv_dirty_bitmap_frozen(bitmap)); > bitmap->disabled =3D false; > + bdrv_dirty_bitmap_unlock(bitmap); Again, why do we need this in addition to BQL? The commit message needs more details about a scenario where our existing BQL lock is insufficient to prevent misuse of bitmap->disabled. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org --bpAfEjNjU9Ku4HeajLlJPcTqiBTBxIOkV Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAloJ23oACgkQp6FrSiUn Q2qHOAf+OAQSeQCPtw7zeEnkX0MbpBr21Ifj6TiNXMO4W+xOXKnjY0z41JlnCY4t l45IIPXCJY0XL89NC+EQGyJ6TSsMnGHnw22zV5O5FCYRQqM9Yv8o5Q6NjWwov8GN 7mgv9MrWPqRur1/0Osj83GmvcUMaAgzGSnuuDvypvt4farfFR+hyOMHNEJVxaSRZ dWAQkLFx+P/OAERGdTjMpFk/lCAmQXG/CH/R4CBFvx8pHldzflQhGPIWiSxrRK4+ TsgRaXIcuoBoFYwSACMPlUZUQUdhm8O3HfppNqujp7TMiWP1S5YHWdZkOPBvZq9K TiYo1hdB5lEf1NrugEmSjOb5C5tJKA== =RNXZ -----END PGP SIGNATURE----- --bpAfEjNjU9Ku4HeajLlJPcTqiBTBxIOkV--