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Tsirkin" To: Xuan Zhuo Cc: netdev@vger.kernel.org, Jason Wang , Eugenio =?iso-8859-1?Q?P=E9rez?= , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , virtualization@lists.linux.dev, bpf@vger.kernel.org Subject: Re: [PATCH net-next 03/13] virtio_ring: packed: harden dma unmap for indirect Message-ID: <20240911072537-mutt-send-email-mst@kernel.org> References: <20240820073330.9161-1-xuanzhuo@linux.alibaba.com> <20240820073330.9161-4-xuanzhuo@linux.alibaba.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20240820073330.9161-4-xuanzhuo@linux.alibaba.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline As gcc luckily noted: On Tue, Aug 20, 2024 at 03:33:20PM +0800, Xuan Zhuo wrote: > @@ -1617,23 +1617,24 @@ static void detach_buf_packed(struct vring_virtqueue *vq, > } > > if (vq->indirect) { > + struct vring_desc_extra *extra; > u32 len; > > /* Free the indirect table, if any, now that it's unmapped. */ > - desc = state->indir_desc; > - if (!desc) desc is no longer initialized here > + extra = state->indir; > + if (!extra) > return; > > if (vring_need_unmap_buffer(vq)) { > len = vq->packed.desc_extra[id].len; > for (i = 0; i < len / sizeof(struct vring_packed_desc); > i++) > - vring_unmap_desc_packed(vq, &desc[i]); > + vring_unmap_extra_packed(vq, &extra[i]); > } > kfree(desc); but freed here > - state->indir_desc = NULL; > + state->indir = NULL; > } else if (ctx) { > - *ctx = state->indir_desc; > + *ctx = state->indir; > } > } It seems unlikely this was always 0 on all paths with even a small amount of stress, so now I question how this was tested. Besides, do not ignore compiler warnings, and do not tweak code to just make compiler shut up - they are your friend. > > -- > 2.32.0.3.g01195cf9f