Re: [PATCH v2] nvmem: properly handle returned value nvmem_reg_read

From: Srinivas Kandagatla
Date: Thu May 10 2018 - 05:58:35 EST




On 09/05/18 19:57, Mathieu Malaterre wrote:
Function nvmem_reg_read can return a non zero value indicating an error.
This returned value must be read and error propagated to
nvmem_cell_prepare_write_buffer. Silence the following gcc warning (W=1):

drivers/nvmem/core.c:1093:9: warning: variable ârcâ set but not used [-Wunused-but-set-variable]

Signed-off-by: Mathieu Malaterre <malat@xxxxxxxxxx>
---
v2: prefer ERR_PTR(-EINVAL) over a simple return NULL

drivers/nvmem/core.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index b05aa8e81303..f7b6c85cf393 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1107,6 +1107,8 @@ static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
/* setup the first byte with lsb bits from nvmem */
rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
+ if (rc)
+ goto err;
*b++ |= GENMASK(bit_offset - 1, 0) & v;
/* setup rest of the byte if any */
@@ -1125,11 +1127,16 @@ static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
/* setup the last byte with msb bits from nvmem */
rc = nvmem_reg_read(nvmem,
cell->offset + cell->bytes - 1, &v, 1);
+ if (rc)
+ goto err;
*p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
}
return buf;
+err:
+ kfree(buf);
+ return ERR_PTR(-EINVAL);
You should return ERR_PTR(rc) not EINVAL here.
errors should always propagate to caller!

thanks,
srini
}
/**