The only difference between comedi_buf_write_alloc() and the *_strict() version is that the *_strict() one will only allocate the chunk if it can completely fulfill the request.
Factor out the common code and add a flag parameter to indicate the 'strict' usage. Change the exported functions so they are just wrappers around the common function. Cleanup the common function a bit and use the comedi_buf_write_n_available() helper to determine the number of bytes available. comedi_buf_write_n_available() is not used outside this module so make it static. Since the only caller is __comedi_buf_write_alloc(), which will always have a valid async pointer and already has a memory barrier, we can remove the unnecessary (async == NULL) test as well as the smp_mb(). Also, the rounding of the sample size can be removed since the caller does not need it. Signed-off-by: H Hartley Sweeten <[email protected]> Cc: Ian Abbott <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> --- drivers/staging/comedi/comedi_buf.c | 52 +++++++++++++++---------------------- drivers/staging/comedi/comedidev.h | 1 - 2 files changed, 21 insertions(+), 32 deletions(-) diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c index 9392453..2f38a87 100644 --- a/drivers/staging/comedi/comedi_buf.c +++ b/drivers/staging/comedi/comedi_buf.c @@ -159,22 +159,30 @@ void comedi_buf_reset(struct comedi_async *async) async->events = 0; } -unsigned int comedi_buf_write_n_available(struct comedi_async *async) +static unsigned int comedi_buf_write_n_available(struct comedi_async *async) { - unsigned int free_end; - unsigned int nbytes; + unsigned int free_end = async->buf_read_count + async->prealloc_bufsz; - if (async == NULL) - return 0; + return free_end - async->buf_write_alloc_count; +} - free_end = async->buf_read_count + async->prealloc_bufsz; - nbytes = free_end - async->buf_write_alloc_count; - nbytes -= nbytes % bytes_per_sample(async->subdevice); - /* barrier insures the read of buf_read_count in this - query occurs before any following writes to the buffer which - might be based on the return value from this query. +static unsigned int __comedi_buf_write_alloc(struct comedi_async *async, + unsigned int nbytes, + int strict) +{ + unsigned int available = comedi_buf_write_n_available(async); + + if (nbytes > available) + nbytes = strict ? 0 : available; + + async->buf_write_alloc_count += nbytes; + + /* + * ensure the async buffer 'counts' are read and updated + * before we write data to the write-alloc'ed buffer space */ smp_mb(); + return nbytes; } @@ -182,16 +190,7 @@ unsigned int comedi_buf_write_n_available(struct comedi_async *async) unsigned int comedi_buf_write_alloc(struct comedi_async *async, unsigned int nbytes) { - unsigned int free_end = async->buf_read_count + async->prealloc_bufsz; - - if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0) - nbytes = free_end - async->buf_write_alloc_count; - - async->buf_write_alloc_count += nbytes; - /* barrier insures the read of buf_read_count above occurs before - we write data to the write-alloc'ed buffer space */ - smp_mb(); - return nbytes; + return __comedi_buf_write_alloc(async, nbytes, 0); } EXPORT_SYMBOL(comedi_buf_write_alloc); @@ -199,16 +198,7 @@ EXPORT_SYMBOL(comedi_buf_write_alloc); unsigned int comedi_buf_write_alloc_strict(struct comedi_async *async, unsigned int nbytes) { - unsigned int free_end = async->buf_read_count + async->prealloc_bufsz; - - if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0) - nbytes = 0; - - async->buf_write_alloc_count += nbytes; - /* barrier insures the read of buf_read_count above occurs before - we write data to the write-alloc'ed buffer space */ - smp_mb(); - return nbytes; + return __comedi_buf_write_alloc(async, nbytes, 1); } /* munging is applied to data by core as it passes between user diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h index c3bc4b7..bf0fd8d 100644 --- a/drivers/staging/comedi/comedidev.h +++ b/drivers/staging/comedi/comedidev.h @@ -438,7 +438,6 @@ comedi_to_usb_interface(struct comedi_device *dev) int comedi_buf_put(struct comedi_async *async, short x); int comedi_buf_get(struct comedi_async *async, short *x); -unsigned int comedi_buf_write_n_available(struct comedi_async *async); unsigned int comedi_buf_write_alloc(struct comedi_async *async, unsigned int nbytes); unsigned int comedi_buf_write_alloc_strict(struct comedi_async *async, -- 1.8.0 _______________________________________________ devel mailing list [email protected] http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
