From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 58B631ED4F for ; Tue, 25 Jul 2023 11:39:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE86AC433C7; Tue, 25 Jul 2023 11:39:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1690285161; bh=NFOiFWo9Qjua7ANl3fbNiLtiuKpX1YuDXkiora1hNNU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HjMf80NRQ2tOT2p2U7fV/5uN/JBJ09ROx3Ga+y2tZnAz047b0jJY6dBTum2ouSqVX PbRAJ3PqANpW2tcLWaaqLphVOA2Bh/AuYGPaw447yNRc4WX1vuW/mXqnD5x4oEM2Gh rD/oAWhKIMmn0LuLhPJGjJuvkb/De0NoHtcDeHVg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Laurent Vivier , "Michael S. Tsirkin" , Sasha Levin Subject: [PATCH 5.4 106/313] hwrng: virtio - dont wait on cleanup Date: Tue, 25 Jul 2023 12:44:19 +0200 Message-ID: <20230725104525.574991387@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230725104521.167250627@linuxfoundation.org> References: <20230725104521.167250627@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Laurent Vivier [ Upstream commit 2bb31abdbe55742c89f4dc0cc26fcbc8467364f6 ] When virtio-rng device was dropped by the hwrng core we were forced to wait the buffer to come back from the device to not have remaining ongoing operation that could spoil the buffer. But now, as the buffer is internal to the virtio-rng we can release the waiting loop immediately, the buffer will be retrieve and use when the virtio-rng driver will be selected again. This avoids to hang on an rng_current write command if the virtio-rng device is blocked by a lack of entropy. This allows to select another entropy source if the current one is empty. Signed-off-by: Laurent Vivier Link: https://lore.kernel.org/r/20211028101111.128049-3-lvivier@redhat.com Signed-off-by: Michael S. Tsirkin Stable-dep-of: ac52578d6e8d ("hwrng: virtio - Fix race on data_avail and actual data") Signed-off-by: Sasha Levin --- drivers/char/hw_random/virtio-rng.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c index 23149e94d621f..c8f5a3392e48c 100644 --- a/drivers/char/hw_random/virtio-rng.c +++ b/drivers/char/hw_random/virtio-rng.c @@ -81,6 +81,11 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) ret = wait_for_completion_killable(&vi->have_data); if (ret < 0) return ret; + /* if vi->data_avail is 0, we have been interrupted + * by a cleanup, but buffer stays in the queue + */ + if (vi->data_avail == 0) + return read; chunk = min_t(unsigned int, size, vi->data_avail); memcpy(buf + read, vi->data, chunk); @@ -104,7 +109,7 @@ static void virtio_cleanup(struct hwrng *rng) struct virtrng_info *vi = (struct virtrng_info *)rng->priv; if (vi->busy) - wait_for_completion(&vi->have_data); + complete(&vi->have_data); } static int probe_common(struct virtio_device *vdev) -- 2.39.2