greybus: es2: test apb1_log_task safely
When usb_log_enable() is called, the global apb1_log_task is used to
hold the result of kthread_run(). It is possible for kthread_run()
to return an error pointer, so tests of apb_log_task against NULL
are insufficient to determine its validity.
Note that kthread_run() never returns NULL so we don't have to check
for that. But apb1_log_task is initially NULL, so that global must
be both non-null and not an error in order to be considered valid.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
diff --git a/drivers/staging/greybus/es2.c b/drivers/staging/greybus/es2.c
index e463750..23e2778 100644
--- a/drivers/staging/greybus/es2.c
+++ b/drivers/staging/greybus/es2.c
@@ -540,12 +540,12 @@
static void usb_log_enable(struct es1_ap_dev *es1)
{
- if (apb1_log_task != NULL)
+ if (!IS_ERR_OR_NULL(apb1_log_task))
return;
/* get log from APB1 */
apb1_log_task = kthread_run(apb1_log_poll, es1, "apb1_log");
- if (apb1_log_task == ERR_PTR(-ENOMEM))
+ if (IS_ERR(apb1_log_task))
return;
apb1_log_dentry = debugfs_create_file("apb1_log", S_IRUGO,
gb_debugfs_get(), NULL,
@@ -554,7 +554,7 @@
static void usb_log_disable(struct es1_ap_dev *es1)
{
- if (apb1_log_task == NULL)
+ if (IS_ERR_OR_NULL(apb1_log_task))
return;
debugfs_remove(apb1_log_dentry);
@@ -568,7 +568,7 @@
size_t count, loff_t *ppos)
{
char tmp_buf[3];
- int enable = apb1_log_task != NULL;
+ int enable = !IS_ERR_OR_NULL(apb1_log_task);
sprintf(tmp_buf, "%d\n", enable);
return simple_read_from_buffer(buf, count, ppos, tmp_buf, 3);