Most comedi subdevices that support asynchronous data acquisition commands only support data transfer in a single direction, as indicated by the `SDF_CMD_READ` and `SDF_CMD_WRITE` subdevice flags. A few allow data transfer in either direction, but only a single direction at a time, as indicated by the `CMDF_WRITE` command flag in the `flags` member of the `struct comedi_cmd` from user-space used to set up the asynchronous command. The `CMDF_WRITE` flag isn't commonly set for "write" commands if that is the only direction the subdevice supports. Since it would be useful for comedi to have a clear indication of which data transfer direction is being used, patch 1 forces the `CMDF_WRITE` command flag to the correct state if only one direction is supported. The flag can then be checked by comedi in the subdevice's local copy of the current command (in `s->async->cmd`) to determine the data transfer direction unambiguously. Patch 2 stops the "me4000" driver clobbering the command flags. Patch 3 removes some now redundant modification of the `CMDF_WRITE` flag in "ni_mio_common.c" (used by the "ni_pcimio", "ni_atmio" and "ni_mio_cs" drivers). Patches 4 and 5 disallow the read() and write() file operations if the subdevice has been set up with a command in the "write" or "read" data transfer direction respectively. Patch 6 changes the readable/writeable checks for the poll() file operation. It already considers the file readable/writeable if read()/write() would fail with an error, so change it to check for "wrong direction" as one of the possible failures. Patch 7 makes the direction test in the handling of the `COMEDI_BUFINFO` ioctl (used to update buffer positions for mmapped buffers) less ambiguous. The current test used the `SDF_CMD_READ` and `SDF_CMD_WRITE` subdevice flags to check the direction, which is ambiguous if both flags are set. Update it to use the `CMDF_WRITE` command flag instead. 1) staging: comedi: maybe force CMDF_WRITE command flag 2) staging: comedi: me4000: don't clobber command flags 3) staging: comedi: ni_mio_common: don't change CMDF_WRITE flag 4) staging: comedi: don't allow read() on async command set up for "write" 5) staging: comedi: don't allow write() on async command set up for "read" 6) staging: comedi: check command direction in poll() file operation 7) staging: comedi: check actual data direction for COMEDI_BUFINFO ioctl drivers/staging/comedi/comedi_fops.c | 37 ++++++++++++++++++++++++-- drivers/staging/comedi/drivers/me4000.c | 3 --- drivers/staging/comedi/drivers/ni_mio_common.c | 6 ----- 3 files changed, 35 insertions(+), 11 deletions(-) _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
