line6_alloc_sysex_buffer() is never called in atomic context.
The call chain ending up at line6_alloc_sysex_buffer() are:
[1] line6_alloc_sysex_buffer() <- pod_alloc_sysex_buffer() <-
pod_set_system_param_int() <- snd_pod_control_monitor_put()
snd_pod_control_monitor_put() is only set as ".put" in snd_kcontrol_new
structure "pod_control_monitor".
And ->put() is called in snd_ctl_elem_write() (sound/core/control.c)
snd_ctl_elem_write() are called in ctl_elem_write_user()
and snd_ctl_elem_write_user().
These functions are not called in atomic context.
Despite never getting called from atomic context,
line6_alloc_sysex_buffer() calls kmalloc with GFP_ATOMIC,
which waits busily for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL
to avoid busy waiting.
This is found by a static analysis tool named DCNS written by myself.
Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
---
sound/usb/line6/driver.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sound/usb/line6/driver.c b/sound/usb/line6/driver.c
index 0ff5a7d..70a509e 100644
--- a/sound/usb/line6/driver.c
+++ b/sound/usb/line6/driver.c
@@ -265,7 +265,7 @@ int line6_send_sysex_message(struct usb_line6 *line6, const char *buffer,
char *line6_alloc_sysex_buffer(struct usb_line6 *line6, int code1, int code2,
int size)
{
- char *buffer = kmalloc(size + SYSEX_EXTRA_SIZE, GFP_ATOMIC);
+ char *buffer = kmalloc(size + SYSEX_EXTRA_SIZE, GFP_KERNEL);
if (!buffer)
return NULL;
--
1.9.1
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