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scope.c: use mutex_lock_killable to prevent unkillable processes #3

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scope.c: use mutex_lock_killable to prevent unkillable processes #3

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14 changes: 8 additions & 6 deletions module/scope.c
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Original file line number Diff line number Diff line change
Expand Up @@ -90,7 +90,7 @@ static int scope_release(struct inode *inode, struct file *file) {
struct scope_data *dev = file->private_data;
if (!dev) return -ENODEV;

mutex_lock(&dev->io_mutex);
mutex_lock_killable(&dev->io_mutex);
if (dev->interface)
usb_autopm_put_interface(dev->interface);
mutex_unlock(&dev->io_mutex);
Expand Down Expand Up @@ -120,7 +120,7 @@ static int scope_send(struct scope_data *dev, const char *cmd,
if (!buff) return -ENOMEM;
memcpy(buff, cmd, count);
int errors = 0;
mutex_lock(&dev->io_mutex);
mutex_lock_killable(&dev->io_mutex);
if (!dev->interface) {
mutex_unlock(&dev->io_mutex);
return -ENODEV;
Expand Down Expand Up @@ -635,7 +635,7 @@ static void scope_trigger_callback(struct scope_data *dev) {

static long scope_io_trigger(struct scope_data *dev) {
unsigned long flags;
mutex_lock(&dev->read_mutex);
mutex_lock_killable(&dev->read_mutex);
spin_lock_irqsave(&dev->state_lock, flags);
enum scope_state state = dev->state;
if (state & SCOPE_READY) {
Expand Down Expand Up @@ -817,7 +817,10 @@ static void scope_disconnect(struct usb_interface *interface) {
usb_kill_anchored_urbs(&dev->in_anchor);
usb_kill_anchored_urbs(&dev->out_anchor);

mutex_lock(&dev->io_mutex);
// Note: when doing rmmod quickly after insmod, a race condition causes this code to wait for the lock forever so it hangs until the next reboot.
// Changed this to use mutex_lock_killable so at least the user can kill the userspace process waiting for the driver.
// Even though this is not a permanent fix, it makes the issue less annoying because it removes the need for a full system restart when this happens.
mutex_lock_killable(&dev->io_mutex);
dev->interface = NULL;
mutex_unlock(&dev->io_mutex);

Expand Down Expand Up @@ -996,8 +999,7 @@ static void scope_draw_down(struct scope_data *dev) {

static int scope_pre_reset(struct usb_interface *intf) {
struct scope_data *dev = usb_get_intfdata(intf);

mutex_lock(&dev->io_mutex);
mutex_lock_killable(&dev->io_mutex);
scope_draw_down(dev);
return 0;
}
Expand Down