diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2013-04-04 13:58:51 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-04-05 21:33:17 (GMT) |
| commit | 07778393d9a8dbc4b9306d20a8ecfe053771ba93 (patch) | |
| tree | 85dfeee58a70d808b837a30e5112ccdaa7fe2b82 /drivers/staging/comedi/comedi_fops.c | |
| parent | 7638ffcb50903d9ddbf605c7e9578d72658a960a (diff) | |
| download | linux-fsl-qoriq-07778393d9a8dbc4b9306d20a8ecfe053771ba93.tar.xz | |
staging: comedi: pre-lock mutex on creation of comedi device
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@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/comedi/comedi_fops.c')
| -rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 7 |
1 files changed, 7 insertions, 0 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); } } |