Tzung-Bi Shih <tzungbi@xxxxxxxxxx> writes: > On Thu, Jun 13, 2024 at 05:51:39PM +0100, Ben Walsh wrote: >> >> Thanks for fixing this! Unfortunately `in_range` returns -EINVAL if >> length == 0 (see the definition of `fwk_ec_lpc_mec_in_range`). I'm sure >> this broke something in my testing, but I can't find what it was now. > > Somewhere like [1] could accidentally get the -EINVAL. > > [1]: https://elixir.bootlin.com/linux/v6.9/source/drivers/platform/chrome/cros_ec_lpc.c#L232 Yes. It turns out I'm getting it in: cros_ec_query_all -> cros_ec_proto_info -> ... -> cros_ec_pkt_xfer_lpc /* Read response and update checksum */ ret = cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PARAM, args.data_size, ^^^^^^^^^^^^^^^ msg->data); (as Dan suggested in his email). >> or 2. Put in a check for length == 0. >> >> or 3. Change the logic in `fwk_ec_lpc_mec_in_range`. Although I'm not >> sure what the correct answer is to "zero length is in range?" >> >> I prefer option 2. What do you think? > > How about drop the length check at [2]? > > [2]: https://elixir.bootlin.com/linux/v6.9/source/drivers/platform/chrome/cros_ec_lpc_mec.c#L44 > This works, but we still end up calling cros_ec_lpc_io_bytes_mec() with zero length. Although this seems to work fine, we could put a length check at the top of cros_ec_lpc_read_bytes() to avoid it. >> >> Dan Carpenter <dan.carpenter@xxxxxxxxxx> writes: >> >> > We changed these functions to returning negative error codes, but this >> > first error path was accidentally overlooked. It leads to a Smatch >> > warning: >> > >> > drivers/platform/chrome/cros_ec_lpc.c:181 ec_response_timed_out() >> > error: uninitialized symbol 'data'. >> > >> > Fix this by returning the error code instead of success. >> > >> > Fixes: 68dbac0a58ef ("platform/chrome: cros_ec_lpc: MEC access can return error code") >> > Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> >> > --- >> > drivers/platform/chrome/cros_ec_lpc.c | 4 ++-- >> > 1 file changed, 2 insertions(+), 2 deletions(-) >> > >> > diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c >> > index ebe9fb143840..f0470248b109 100644 >> > --- a/drivers/platform/chrome/cros_ec_lpc.c >> > +++ b/drivers/platform/chrome/cros_ec_lpc.c >> > @@ -139,7 +139,7 @@ static int cros_ec_lpc_mec_read_bytes(unsigned int offset, unsigned int length, >> > int in_range = cros_ec_lpc_mec_in_range(offset, length); >> > >> > if (in_range < 0) >> > - return 0; >> > + return in_range; >> > >> > return in_range ? >> > cros_ec_lpc_io_bytes_mec(MEC_IO_READ, >> > @@ -158,7 +158,7 @@ static int cros_ec_lpc_mec_write_bytes(unsigned int offset, unsigned int length, >> > int in_range = cros_ec_lpc_mec_in_range(offset, length); >> > >> > if (in_range < 0) >> > - return 0; >> > + return in_range; >> > >> > return in_range ? >> > cros_ec_lpc_io_bytes_mec(MEC_IO_WRITE, >> > -- >> > 2.43.0 >>
