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Wed, 24 Mar 2021 09:23:36 -0700 (PDT) Received: from localhost ([51.15.41.238]) by smtp.gmail.com with ESMTPSA id bm10sm1388596edb.2.2021.03.24.09.23.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Mar 2021 09:23:35 -0700 (PDT) Date: Wed, 24 Mar 2021 16:23:34 +0000 From: Stefan Hajnoczi To: Paolo Bonzini Subject: Re: [PATCH v5 0/6] coroutine rwlock downgrade fix, minor VDI changes Message-ID: References: <20210317180013.235231-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="+NLek3ZWZlLEcYJM" Content-Disposition: inline In-Reply-To: <20210317180013.235231-1-pbonzini@redhat.com> Received-SPF: pass client-ip=2a00:1450:4864:20::62c; envelope-from=stefanha@gmail.com; helo=mail-ej1-x62c.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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: david.edmondson@oracle.com, kwolf@redhat.com, qemu-devel@nongnu.org, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --+NLek3ZWZlLEcYJM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Mar 17, 2021 at 07:00:07PM +0100, Paolo Bonzini wrote: > This is a resubmit of David Edmondson's series at > https://patchew.org/QEMU/20210309144015.557477-1-david.edmondson@oracle.c= om/. > After closer analysis on IRC, the CoRwlock's attempt to ensure > fairness turned out to be flawed. Therefore, this series > reimplements CoRwlock without using a CoQueue. Tracking whether > each queued coroutine is a reader/writer makes it possible to > never wake a writer when only readers should be allowed and > vice versa. >=20 > v2->v3: new CoRwlock implementation >=20 > v3->v4: fix upgrade and add a test for that, too >=20 > v4->v5: typo >=20 > David Edmondson (4): > block/vdi: When writing new bmap entry fails, don't leak the buffer > block/vdi: Don't assume that blocks are larger than VdiHeader > coroutine/mutex: Store the coroutine in the CoWaitRecord only once > test-coroutine: Add rwlock downgrade test >=20 > Paolo Bonzini (2): > coroutine-lock: reimplement CoRwlock to fix downgrade bug > test-coroutine: add rwlock upgrade test >=20 > block/vdi.c | 11 ++- > include/qemu/coroutine.h | 17 ++-- > tests/unit/test-coroutine.c | 161 ++++++++++++++++++++++++++++++++++++ > util/qemu-coroutine-lock.c | 149 +++++++++++++++++++++------------ > 4 files changed, 274 insertions(+), 64 deletions(-) I had questions about the rwlock implementation. The other patches look ready to go. Stefan --+NLek3ZWZlLEcYJM Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmBbZ4YACgkQnKSrs4Gr c8hTFggAtLWv3SuPyFOj/SjCMQd6UhwWVot7oilb9k2TgqEHj/4GI2dFU/i/MHSb DlLYdflztMm394EEYOoVSVbEvlhne5+IYV3t6ZEe0mfxhdfHxvi1R0iFWx2U4zOB Wngp3uisnvAOtAROw+69JgD4lqtdsRQCRj0Gldoa1QlnrJTQKaUO618LNqEdYAP+ Lg/tA84uiMKNyLMKEb4Ly3JE9wmI8/NCJ4H8Q/enYGQFxra0GSbH3d6hucbk9W1i feC8d3E4VBOfm7FlvQjvVvZMDRH8oxB+yYg59chi/9V0zjViEH4flZ6Tzx43qrmf HkH6ufOidfqEp3emQ99PCBR0C5LeGA== =YCtt -----END PGP SIGNATURE----- --+NLek3ZWZlLEcYJM--