Return from `comedi_alloc_board_minor()` with the mutex of the created
`struct comedi_device` pre-locked. This allows further initialization
by the caller without the worry of something getting in there first.
`comedi_auto_config()` no longer needs to check if the device is already
"attached" since whatever was trying to attach the device would need to
have locked the mutex first.
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
drivers/staging/comedi/comedi_fops.c | 7 +++++++
drivers/staging/comedi/drivers.c | 6 ++----
2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index f9d0a72..061b55b 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -2274,6 +2274,7 @@ static void comedi_device_cleanup(struct comedi_device *dev)
mutex_destroy(&dev->mutex);
}
+/* Note: the ->mutex is pre-locked on successful return */
struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device)
{
struct comedi_file_info *info;
@@ -2292,6 +2293,7 @@ struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device)
info->device = dev;
info->hardware_device = hardware_device;
comedi_device_init(dev);
+ mutex_lock(&dev->mutex);
spin_lock(&comedi_file_info_table_lock);
for (i = 0; i < COMEDI_NUM_BOARD_MINORS; ++i) {
if (comedi_file_info_table[i] == NULL) {
@@ -2301,6 +2303,7 @@ struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device)
}
spin_unlock(&comedi_file_info_table_lock);
if (i == COMEDI_NUM_BOARD_MINORS) {
+ mutex_unlock(&dev->mutex);
comedi_device_cleanup(dev);
kfree(dev);
kfree(info);
@@ -2314,6 +2317,7 @@ struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device)
dev->class_dev = csdev;
dev_set_drvdata(csdev, info);
+ /* Note: dev->mutex needs to be unlocked by the caller. */
return dev;
}
@@ -2485,6 +2489,9 @@ static int __init comedi_init(void)
unregister_chrdev_region(MKDEV(COMEDI_MAJOR, 0),
COMEDI_NUM_MINORS);
return PTR_ERR(dev);
+ } else {
+ /* comedi_alloc_board_minor() locked the mutex */
+ mutex_unlock(&dev->mutex);
}
}
diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c
index 0b72af8..caadd3b 100644
--- a/drivers/staging/comedi/drivers.c
+++ b/drivers/staging/comedi/drivers.c
@@ -429,11 +429,9 @@ int comedi_auto_config(struct device *hardware_device,
comedi_dev = comedi_alloc_board_minor(hardware_device);
if (IS_ERR(comedi_dev))
return PTR_ERR(comedi_dev);
+ /* Note: comedi_alloc_board_minor() locked comedi_dev->mutex. */
- mutex_lock(&comedi_dev->mutex);
- if (comedi_dev->attached)
- ret = -EBUSY;
- else if (!try_module_get(driver->module))
+ if (!try_module_get(driver->module))
ret = -EIO;
else {
comedi_set_hw_dev(comedi_dev, hardware_device);
--
1.8.1.5
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