Messages in this thread Patch in this message | | | From | Michael Ellerman <> | Subject | [PATCH] Store the relevant miscdevice in file->private_data in misc_open() | Date | Thu, 13 Nov 2008 15:49:50 +1100 (EST) |
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Currently it's not easy to share file_operations between multiple instances of a miscdevice. In order to do this, the device code needs to store a list of all it's miscdevice instances, and when fops->open() is called, search the list and find the right device based on the minor number.
However the generic miscdevice code already has a list of miscdevices, and uses this to find the right device in misc_open(). If misc_open() would store the miscdevice it found in file->private_data, then the device code wouldn't need to worry about storing it's own separate list and searching that as well.
The rest of the miscdevice code does not use file->private_data, so the device code is still free to use file->private_data for something else if it wants to.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
--- I'm not all that across VFS or driver core stuff, but this looks safe to me, lots of other devices use file->private_data and this should be no different AFAICT.
drivers/char/misc.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/drivers/char/misc.c b/drivers/char/misc.c index a5e0db9..bb91d68 100644 --- a/drivers/char/misc.c +++ b/drivers/char/misc.c @@ -147,11 +147,13 @@ static int misc_open(struct inode * inode, struct file * file) err = 0; old_fops = file->f_op; file->f_op = new_fops; + file->private_data = c; if (file->f_op->open) { err=file->f_op->open(inode,file); if (err) { fops_put(file->f_op); file->f_op = fops_get(old_fops); + file->private_data = NULL; } } fops_put(old_fops); -- 1.5.5
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