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auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="RqR3UCEfjpt1sdRo" Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.697, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fam@euphon.net, kwolf@redhat.com, qemu-block@nongnu.org, eesposit@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --RqR3UCEfjpt1sdRo Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Apr 22, 2021 at 01:09:50AM +0300, Vladimir Sementsov-Ogievskiy wrote: > @@ -1981,8 +1985,15 @@ bdrv_co_write_req_prepare(BdrvChild *child, int64_t offset, int64_t bytes, > } else { > assert(child->perm & BLK_PERM_WRITE); > } > - return notifier_with_return_list_notify(&bs->before_write_notifiers, > - req); > + write_threshold = qatomic_read(&bs->write_threshold_offset); > + if (write_threshold > 0 && offset + bytes > write_threshold) { > + qapi_event_send_block_write_threshold( > + bs->node_name, > + offset + bytes - write_threshold, > + write_threshold); > + qatomic_set(&bs->write_threshold_offset, 0); It's safer to reset the threshold before emitting the event. That way there is no race with the QMP client setting a new threshold via bdrv_write_threshold_is_set(). I guess the race is possible since qatomic is used and there is no lock. I like the idea of dropping write notifiers: Acked-by: Stefan Hajnoczi --RqR3UCEfjpt1sdRo Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmCSbwsACgkQnKSrs4Gr c8hV0wf/SBPqlOh0bTpFGr3h+z/EnHXqdeVgwcApos1wBTPsMHh52v+K4hNVnKjO 1ETTQ+IiMSMqmEmwjLRxpRXnojeUg+GGmIf+JPYqmX2UeOmjmrEsjLdMWh2kAsf0 R97zkQ9zAAeGRlNoQgIUHyBXWqWNpCbxqYgyGiBnQKBFPQXRgSKcSu+DYaoS/F64 cV8eTsj9ssz8RCz0fepvGfVUNdXX2qTWuCBuPlaoWEDfu35M85AT0aQVoub/pD83 knylIXhbmmgDAQhqcRdY2Q6OvonmRkCtpXKYCI5qsgTkqTROwmxtSsNKHkYw9jL/ 4ENL88WYm5IrxhTuSDYWeGx03Q/Y9w== =TzLW -----END PGP SIGNATURE----- --RqR3UCEfjpt1sdRo--