2021-03-22 20:43:30

by Emmanuel Grumbach

[permalink] [raw]
Subject: [PATCH 1/5] mei: allow map and unmap of client dma buffer only for disconnected client

From: Tomas Winkler <[email protected]>

Allow map and unmap of the client dma buffer only when the client is not
connected. The functions return -EPROTO if the client is already connected.
This is to fix the race when traffic may start or stop when buffer
is not available.

Signed-off-by: Tomas Winkler <[email protected]>
Signed-off-by: Emmanuel Grumbach <[email protected]>
---
drivers/misc/mei/client.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/misc/mei/client.c b/drivers/misc/mei/client.c
index 4378a9b25848..2cc370adb238 100644
--- a/drivers/misc/mei/client.c
+++ b/drivers/misc/mei/client.c
@@ -2286,8 +2286,8 @@ int mei_cl_dma_alloc_and_map(struct mei_cl *cl, const struct file *fp,
if (buffer_id == 0)
return -EINVAL;

- if (!mei_cl_is_connected(cl))
- return -ENODEV;
+ if (mei_cl_is_connected(cl))
+ return -EPROTO;

if (cl->dma_mapped)
return -EPROTO;
@@ -2327,9 +2327,7 @@ int mei_cl_dma_alloc_and_map(struct mei_cl *cl, const struct file *fp,

mutex_unlock(&dev->device_lock);
wait_event_timeout(cl->wait,
- cl->dma_mapped ||
- cl->status ||
- !mei_cl_is_connected(cl),
+ cl->dma_mapped || cl->status,
mei_secs_to_jiffies(MEI_CL_CONNECT_TIMEOUT));
mutex_lock(&dev->device_lock);

@@ -2376,8 +2374,9 @@ int mei_cl_dma_unmap(struct mei_cl *cl, const struct file *fp)
return -EOPNOTSUPP;
}

- if (!mei_cl_is_connected(cl))
- return -ENODEV;
+ /* do not allow unmap for connected client */
+ if (mei_cl_is_connected(cl))
+ return -EPROTO;

if (!cl->dma_mapped)
return -EPROTO;
@@ -2405,9 +2404,7 @@ int mei_cl_dma_unmap(struct mei_cl *cl, const struct file *fp)

mutex_unlock(&dev->device_lock);
wait_event_timeout(cl->wait,
- !cl->dma_mapped ||
- cl->status ||
- !mei_cl_is_connected(cl),
+ !cl->dma_mapped || cl->status,
mei_secs_to_jiffies(MEI_CL_CONNECT_TIMEOUT));
mutex_lock(&dev->device_lock);

--
2.25.1