[PATCH 4.4 047/138] remoteproc: Fix potential race condition in rproc_add

Greg Kroah-Hartman
2016-08-18T14:04:39Z

From: Dave Gerlach <d-gerlach@ti.com>

commit d2e12e66a939c54ed84e5f1b6947f0c45f6c56eb upstream.

rproc_add adds the newly created remoteproc to a list for use by
rproc_get_by_phandle and then does some additional processing to finish
adding the remoteproc. This leaves a small window of time in which the
rproc is available in the list but not yet fully initialized, so if
another driver comes along and gets a handle to the rproc, it will be
invalid. Rearrange the code in rproc_add to make sure the rproc is added
to the list only after it has been successfuly initialized.

Fixes: fec47d863587 ("remoteproc: introduce rproc_get_by_phandle API")
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/remoteproc/remoteproc_core.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -1239,11 +1239,6 @@ int rproc_add(struct rproc *rproc)
if (ret < 0)
return ret;

- /* expose to rproc_get_by_phandle users */
- mutex_lock(&rproc_list_mutex);
- list_add(&rproc->node, &rproc_list);
- mutex_unlock(&rproc_list_mutex);
-
dev_info(dev, "%s is available\n", rproc->name);

dev_info(dev, "Note: remoteproc is still under development and considered experimental.\n");
@@ -1251,8 +1246,16 @@ int rproc_add(struct rproc *rproc)

/* create debugfs entries */
rproc_create_debug_dir(rproc);
+ ret = rproc_add_virtio_devices(rproc);
+ if (ret < 0)
+ return ret;
+
+ /* expose to rproc_get_by_phandle users */
+ mutex_lock(&rproc_list_mutex);
+ list_add(&rproc->node, &rproc_list);
+ mutex_unlock(&rproc_list_mutex);

- return rproc_add_virtio_devices(rproc);
+ return 0;
}
EXPORT_SYMBOL(rproc_add);