muser, libmuser: Do not abuse muser_cmd.mmap.response to return err

muser_cmd.mmap.response is unsigned and should not be used to return
errors, instead use muser_cmd.err
Also fixed the code path to use valid errno values.

Signed-off-by: Swapnil Ingle <swapnil.ingle@nutanix.com>

2 files changed, 10 insertions, 22 deletions

diff --git a/kmod/muser.c b/kmod/muser.c
index 54e3e70..7ee5926 100644
--- a/kmod/muser.c
+++ b/kmod/muser.c
@@ -605,7 +605,7 @@ static int muser_process_dma_request(struct muser_dev *mudev,
 	if (unlikely(err))
 		return err;
 
-	return mucmd.muser_cmd.mmap.response;
+	return mucmd.muser_cmd.err;
 }
 
 static int muser_process_dma_map(struct muser_dev *mudev, int flags)
@@ -1478,9 +1478,6 @@ static inline int mmap_done(struct mudev_cmd * const mucmd)
 	char __user *addr = (char __user *) cmd->mmap.response;
 	int ret;
 
-	if (cmd->err < 0)
-		return -EINVAL;
-
 	ret = do_pin_pages(addr, mucmd->mmap_len, 1, &mucmd->pg_map);
 	if (ret) {
 		muser_alert("failed to pin pages: %d", ret);
@@ -1497,7 +1494,7 @@ static long libmuser_unl_ioctl(struct file *filep, unsigned int cmd,
 	struct muser_dev *mudev = filep->private_data;
 	struct mudev_cmd *mucmd;
 	unsigned long offset;
-	int ret = -EINVAL;
+	int ret = -EINVAL, mucmd_err;
 
 	WARN_ON(mudev == NULL);
 	switch (cmd) {
@@ -1552,6 +1549,7 @@ static long libmuser_unl_ioctl(struct file *filep, unsigned int cmd,
 		if (ret)
 			goto out;
 
+		mucmd_err = mucmd->muser_cmd.err;
 		switch (mucmd->type) {
 		case MUSER_IOCTL:
 			offset = offsetof(struct muser_cmd, ioctl);
@@ -1559,13 +1557,12 @@ static long libmuser_unl_ioctl(struct file *filep, unsigned int cmd,
 			ret = bounce_in(mucmd, (void __user *)(arg + offset));
 			break;
 		case MUSER_MMAP:
-			ret = mmap_done(mucmd);
+			if (!mucmd_err)
+				ret = mmap_done(mucmd);
 			break;
 		case MUSER_READ:
-			if (mucmd->muser_cmd.err < 0) {
-				muser_alert("read failed: %d",
-			        mucmd->muser_cmd.err);
-			}
+			if (mucmd_err < 0)
+				muser_alert("read failed: %d", mucmd_err);
 			break;
 		case MUSER_WRITE:
 		case MUSER_DMA_MMAP:
diff --git a/lib/libmuser.c b/lib/libmuser.c
index fcfdfd2..4233023 100644
--- a/lib/libmuser.c
+++ b/lib/libmuser.c
@@ -540,8 +540,7 @@ muser_dma_unmap(lm_ctx_t *lm_ctx, struct muser_cmd *cmd)
 
     if (lm_ctx->dma == NULL) {
         lm_log(lm_ctx, LM_ERR, "DMA not initialized\n");
-        cmd->mmap.response = -1;
-        return -1;
+        return -EINVAL;
     }
 
     err = dma_controller_remove_region(lm_ctx->dma,
@@ -553,8 +552,6 @@ muser_dma_unmap(lm_ctx_t *lm_ctx, struct muser_cmd *cmd)
                cmd->mmap.request.len, cmd->mmap.request.addr, strerror(err));
     }
 
-    cmd->mmap.response = err;
-
     return err;
 }
 
@@ -568,8 +565,7 @@ muser_dma_map(lm_ctx_t *lm_ctx, struct muser_cmd *cmd)
 
     if (lm_ctx->dma == NULL) {
         lm_log(lm_ctx, LM_ERR, "DMA not initialized\n");
-        cmd->mmap.response = -1;
-        return -1;
+        return -EINVAL;
     }
 
     err = dma_controller_add_region(lm_ctx, lm_ctx->dma,
@@ -579,12 +575,9 @@ muser_dma_map(lm_ctx_t *lm_ctx, struct muser_cmd *cmd)
     if (err < 0) {
         lm_log(lm_ctx, LM_ERR, "failed to add DMA region %#lx@%#lx: %d\n",
                cmd->mmap.request.len, cmd->mmap.request.addr, err);
-        cmd->mmap.response = -1;
-        return -1;
+        return err;
     }
 
-    cmd->mmap.response = 0;
-
     return 0;
 }
 
@@ -624,8 +617,6 @@ out:
     if (err != 0) {
         lm_log(lm_ctx, LM_ERR, "failed to mmap device memory %#x@%#lx: %s\n",
                len, offset, strerror(-errno));
-        cmd->err = err;
-        err = -1;
     }
 
     return err;