loop: Improve the hw_queue_depth kernel module parameter implementation

Make the following minor changes which were reported by colleagues
while reviewing this code:
- Remove the parentheses from around the LOOP_DEFAULT_HW_Q_DEPTH
  definition since these are superfluous.
- Accept other number formats than decimal, e.g. hexadecimal.
- Do not set hw_queue_depth to an out-of-range value, even if that value
  won't be used.
- Use the LOOP_DEFAULT_HW_Q_DEPTH macro in the kernel module parameter
  description to prevent that the description gets out of sync.

This patch has been tested as follows:

 # modprobe -r loop
 # modprobe loop hw_queue_depth=-1
 modprobe: ERROR: could not insert 'loop': Invalid argument
 # modprobe loop hw_queue_depth=0
 modprobe: ERROR: could not insert 'loop': Invalid argument
 # modprobe loop hw_queue_depth=1; cat /sys/module/loop/parameters/hw_queue_depth
 1
 # modprobe -r loop; modprobe loop; cat /sys/module/loop/parameters/hw_queue_depth hw_queue_depth=0x10
 16
 # modprobe -r loop; modprobe loop; cat /sys/module/loop/parameters/hw_queue_depth hw_queue_depth=128
 128
 # modprobe -r loop; modprobe loop hw_queue_depth=129; cat /sys/module/loop/parameters/hw_queue_depth
 129
 # modprobe -r loop; modprobe loop hw_queue_depth=$((1<<32))
 modprobe: ERROR: could not insert 'loop': Numerical result out of range

See also commit ef44c50837ab ("loop: allow user to set the queue
depth").

Cc: Chaitanya Kulkarni <[email protected]>
Cc: Himanshu Madhani <[email protected]>
Signed-off-by: Bart Van Assche <[email protected]>
Reviewed-by: Chaitanya Kulkarni <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions