On 04/12/2018 19:07, Spencer E. Olson wrote:
Changes do_insn*_ioctl functions to allow for data lengths for each
comedi_insn of up to 2^16. This patch also changes these functions to only
allocate as much memory as is necessary for each comedi_insn, rather than
allocating a fixed-sized scratch space.
In testing some user-space code for the new INSN_DEVICE_CONFIG_GET_ROUTES
facility with some newer hardware, I discovered that do_insn_ioctl and
do_insnlist_ioctl limited the amount of data that can be passed into the
kernel for insn's to a length of 256. For some newer hardware, the number
of routes can be greater than 1000. Working around the old limits (256)
would complicate the user-space/kernel interaction.
The new upper limit is reasonable with current memory available and does
not otherwise impact the memory footprint for any current or otherwise
typical configuration.
Signed-off-by: Spencer E. Olson <olsonse@xxxxxxxxx>
---
Implements Ian's suggestions to:
1) Provide a minimum amount of space to allocate (16*sizeof(uint)) to protect
drivers that do not (yet) check the size of the instruction data (Ian has
submitted several patches fixing this for other drivers already). In case
insn.n does not get set, this minimum amount also avoids trying to allocate
zero-length data.
2) Allocate the maximum required space needed for any of the instructions in an
instruction list before executing the list of instructions (this, rather than
allocating and freeing memory separately while iterating through the
instruction list and executing each instruction).
drivers/staging/comedi/comedi_fops.c | 48 ++++++++++++++++++----------
1 file changed, 31 insertions(+), 17 deletions(-)
Looks good, thanks! (I still need to crack on and fix up the remaining
drivers that ignore insn->n.)
Reviewed-by: Ian Abbott <abbotti@xxxxxxxxx>
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