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[81.40.121.39]) by smtp.gmail.com with ESMTPSA id d18sm9900402eja.71.2021.05.10.13.08.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 May 2021 13:08:10 -0700 (PDT) From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= To: qemu-devel@nongnu.org Subject: [PATCH v3 2/2] virtio-blk: Convert QEMUBH callback to "bitops.h" API Date: Mon, 10 May 2021 22:07:58 +0200 Message-Id: <20210510200758.2623154-3-philmd@redhat.com> X-Mailer: git-send-email 2.26.3 In-Reply-To: <20210510200758.2623154-1-philmd@redhat.com> References: <20210510200758.2623154-1-philmd@redhat.com> MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=philmd@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=philmd@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=-0.698, 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=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: Kevin Wolf , Sergio Lopez , Stefan Hajnoczi , qemu-block@nongnu.org, Richard Henderson , Max Reitz , Chai Wen , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" By directly using find_first_bit() and find_next_bit from the "bitops.h" API to iterate over the bitmap, we can remove the bitmap[] variable-length array copy on the stack and the complex manual bit testing/clearing logic. Suggested-by: Stefan Hajnoczi Suggested-by: Richard Henderson Reviewed-by: Richard Henderson Signed-off-by: Philippe Mathieu-Daudé --- hw/block/dataplane/virtio-blk.c | 20 +++++--------------- 1 file changed, 5 insertions(+), 15 deletions(-) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index e9050c8987e..a31fa94ca33 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -60,24 +60,14 @@ static void notify_guest_bh(void *opaque) { VirtIOBlockDataPlane *s = opaque; unsigned nvqs = s->conf->num_queues; - unsigned long bitmap[BITS_TO_LONGS(nvqs)]; - unsigned j; - memcpy(bitmap, s->batch_notify_vqs, sizeof(bitmap)); - memset(s->batch_notify_vqs, 0, sizeof(bitmap)); + for (unsigned long i = find_first_bit(s->batch_notify_vqs, nvqs); + i < nvqs; i = find_next_bit(s->batch_notify_vqs, nvqs, i)) { + VirtQueue *vq = virtio_get_queue(s->vdev, i); - for (j = 0; j < nvqs; j += BITS_PER_LONG) { - unsigned long bits = bitmap[j / BITS_PER_LONG]; - - while (bits != 0) { - unsigned i = j + ctzl(bits); - VirtQueue *vq = virtio_get_queue(s->vdev, i); - - virtio_notify_irqfd(s->vdev, vq); - - bits &= bits - 1; /* clear right-most bit */ - } + virtio_notify_irqfd(s->vdev, vq); } + bitmap_clear(s->batch_notify_vqs, 0, nvqs); } /* Context: QEMU global mutex held */ -- 2.26.3