Re: [linux-nvme:nvme-5.19] BUILD SUCCESS WITH WARNING 4db675888cdb7b24812e289d7f90e7928dd400a3

[Christoph Hellwig <hch@lst.de>]

On Thu, Jun 30, 2022 at 01:58:42PM +0800, kernel test robot wrote:
> tree/branch: git://git.infradead.org/nvme.git nvme-5.19
> branch HEAD: 4db675888cdb7b24812e289d7f90e7928dd400a3  nvmet: add a clear_ids attribute for passthru targets
> 
> Warning: (recently discovered and may have been fixed)
> 
> drivers/nvme/target/passthru.c:54:16: warning: variable 'csi_seen' is used uninitialized whenever 'for' loop exits because its condition is false [-Wsometimes-uninitialized]
> drivers/nvme/target/passthru.c:57:7: warning: variable 'csi_seen' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]

I ended up fixing this with the patch below.  Alan, let me know
if this works for you:

diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
index d71ed297ad16b..6f39a29828b12 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -33,10 +33,9 @@ void nvmet_passthrough_override_cap(struct nvmet_ctrl *ctrl)
 static u16 nvmet_passthru_override_id_descs(struct nvmet_req *req)
 {
 	struct nvmet_ctrl *ctrl = req->sq->ctrl;
-	struct nvme_ns_id_desc *cur;
 	u16 status = NVME_SC_SUCCESS;
 	int pos, len;
-	bool csi_seen;
+	bool csi_seen = false;
 	void *data;
 	u8 csi;
 
@@ -52,26 +51,25 @@ static u16 nvmet_passthru_override_id_descs(struct nvmet_req *req)
 		goto out_free;
 
 	for (pos = 0; pos < NVME_IDENTIFY_DATA_SIZE; pos += len) {
-		cur = data + pos;
+		struct nvme_ns_id_desc *cur = data + pos;
 
 		if (cur->nidl == 0)
 			break;
-		len = cur->nidl;
 		if (cur->nidt == NVME_NIDT_CSI) {
-			memcpy(&csi, data + pos + sizeof(struct nvme_ns_id_desc),
-			       NVME_NIDT_CSI_LEN);
-			csi_seen = 1;
+			memcpy(&csi, cur + 1, NVME_NIDT_CSI_LEN);
+			csi_seen = true;
 			break;
 		}
-		len += sizeof(struct nvme_ns_id_desc);
+		len = sizeof(struct nvme_ns_id_desc) + cur->nidl;
 	}
 
 	memset(data, 0, NVME_IDENTIFY_DATA_SIZE);
 	if (csi_seen) {
-		cur = data;
+		struct nvme_ns_id_desc *cur = data;
+
 		cur->nidt = NVME_NIDT_CSI;
 		cur->nidl = NVME_NIDT_CSI_LEN;
-		memcpy(data + sizeof(struct nvme_ns_id_desc), &csi,  NVME_NIDT_CSI_LEN);
+		memcpy(cur + 1, &csi, NVME_NIDT_CSI_LEN);
 	}
 	status = nvmet_copy_to_sgl(req, 0, data, NVME_IDENTIFY_DATA_SIZE);
 out_free: